PC HELP
Internet Address - 
ElectrkBlu@AOL.COM 106 2d Twin 
Willow Ct.
Owings Mills, MD 21117
Understanding the IBM Compatible
or
How to do it yourself and leave me alone
**********DISCLAIMER********** 
	Although I believe this to be a project that any reasonably intelligent person can accomplish, the Author assumes no responsibility for 
failed attempts, errors, omissions or injuries or losses connected to the use of the information contained herein. If you need help, get it.  If you are 
not sure, ask.  So there.  
_Copyright 1990,1991,1992,1993,1994 DJ Elliott. All Rights Reserved. 
This is the TEXT version of the document. You are missing some real cheesy graphics and formatting.
If received via BBS 
I INVITE YOUR COMMENTS AND YOUR CRITICISM.  PLEASE SEND ME YOUR RESPONSE. YOU ARE FREE 
TO UPLOAD IT TO OTHER BBS'S IN ITS ENTIRETY WITH NO CHANGES TO THE TEXT. COMMENTS SHOULD 
BE OUTSIDE OF THE ARTICLE.
	DJE December, 1993                                                      Version 3
	Revision History- Original November, 1989 as Build your own IBM Compatible 
	This is a living document. It is corrected and expanded constantly. Below is the date of the latest modification.
December 31, 1993
HARD COPIES ARE AVAILABLE FOR $5.00 FROM THE ABOVE ADDRESS. FIVE OR MORE COPIES $3.00 EACH. 
1,000 OR MORE COPIES INCLUDE DINNER AT MY PLACE AND A SHOE SHINE.
Understanding an IBM Compatible Computer 
by DJ Elliott
Since you are reading this book, you probably fall into one of the following categories:
Build it yourself?
With very little know how and using only what you already know about IBM Compatible Computers, it is an easy and enjoyable task to assemble an 80386 
Machine for a total of under $800, or a 486 for a little more. This machine will look like a store model and do everything a store bought system will do, and 
leave you $500 or more for other pursuits. 
The Machine can be built in your spare time in a few days, or over a number of weeks or months, adding the parts as you can afford them and find them at 
the right price. 
In 1987, this author, knowing absolutely zilch about the inside of a computer, over three months of occasional work and 
with no formal training, originally built a 12 MHz 80286 Compatible Machine with 2048K Memory, a 5 1/4 and 3 1/2 Inch drive, a 10 meg hard disk, 
Parallel and Serial Ports, and a 1200 bps Modem. Actual work time was in the neighborhood of 10 hours.  A soldering gun was used ONCE, to add a 
switch (optional for my uses).  The gun was the most technical piece 
of equipment used.  There was no test equipment, special tools or mathematics involved. Since that time, I have assisted in the building of many machines. Over 
2100 people have downloaded this book. Once you start, you are hooked. I have since changed to an 80486 motherboard, increased memory to 5 megs and I 
constantly improve and upgrade the machine as I 
learn more, which is the real lasting fun of the project. The original machine is on it's fourth owner.
Why build a computer instead of buying it? MONEY and fun.  This machine would easily go for between $1500 and $2000. 
Most parts are under warranty, and you are not "stuck" with a computer that does not work.  Just have the offending part replaced or serviced. 
Compatibility-  What makes this process nearly idiot proof is the architecture- everything plugs in or screws together.  If you can build a model car with Legos or 
hook up a stereo, you can accomplish this. 
When IBM made the first PC, they were under the gun to produce a unit to Market in one year flat - so, in a move they haven't duplicated since (and they haven't 
had a hit since), they used off the shelf, standard parts for the hardware. This decision years ago that the MS-DOS PC would be an Open Architecture System- 
gave the world a system that could be 
cloned and duplicated, and created today's world of almost single standard computing. It gave us all the ability to run with the big boys and made Apple an also 
ran. 
Whatever part it is that you are looking for, it is made by a number of different manufacturers at a number of different price points, and, wonder of wonders- they 
fit into the same slot the same way.  An ABC Motherboard accepts a DEF Controller, which runs a GHI Hard Drive, which fits into a JKL kit, and takes MNO 
disks. 
This book has evolved from a five page general outline to it's present state. As of the version 2, the article includes a short preface so that you can first evaluate the 
project, followed by lengthier information that you will most definitely need wither to narrow down your final buying decision or to support you as you debug your 
hardware.
There is very little to fear in making the decision to plunge ahead with this project. It is very hard to fail as long as you have confidence in yourself, and simply a desire to 
let the little guy win for a change. 
Already Bought It?
Having second thoughts about the power and abilities of what you have? That's ok. You can make the best of what you have 
for now by learning about what's under the hood in the following pages. You will learn how to upgrade what's on the desk to a truly good machine. You 
will learn whether or not your machine is true ISA (Industry Standard Architecture) and can 
be upgraded directly, or if you need to rip out a major part of the system. Don't worry... 99% of compatibles are just that. Unless of course, you bought a 
Pxxxxxd-Bxxl from Cxxxxxxr Cxxy or someplace, in which case you have my sympathies. 
This IS NOT an ISA machine. Many people waste hours and hours of my time talking about their impending purchase. 
They sit in my living room, eat my food, play around on my machine, then go and buy one of those aforementioned junk machines. They deserve them.
Ready to Upgrade?
This book will help you understand the total machine picture, so that you can decide whether it's best to get a bigger hard drive, add memory or replace the 
motherboard.
Just Itching to Learn More?
You've come to the right place.
For those of you about to fight your first C:\> prompt, we salute you.: A section for the new user.
Welcome to the world of DOS and IBM.
This unique planet is a place like no other you have ever been. Your previous experience with other computer platforms will only be a good leg up on 
the total novice due to the unique nature of the DOS platform IBM Clone.
There will be sections to follow that are of no interest whatsoever to you. Feel free to skip them, but I urge you to at least scan the contents; you may 
very well find information that you will want to refer to in a later life.
The message of the book is this: If you ever want to do more than play an occasional game and flounder around 
the DOS prompt, calling some $50 an hour guy every time you get an error message, so be it. The world is full of guys who call a $75 an hour 
electrician to hook up a new phone or speakers to their stereo. I would rather spend $75 on a better phone or better speakers, and have the 
knowledge of how to do it. Many people beg me for a 
copy of this book, and then, two months later, I talk to them and they haven't "gotten around to looking at it" but have "gotten around to" buying a 
$3000 piece of crap computer from BigCity Computer Superstore. Don't waste 
my time or half a tree. You can do this and it will be fun

Let's plunge into the subject with a quick look at the players.
SECTION 1 - A short Industry Overview
Who's Who in Nerddom
Understanding use of the machine has as much to do with the personality of it's developers as with actual technical knowledge. Things are the way 
they are because the PC was designed by men and women driven by other than normal business pursuits. Let's meet a couple of key players who 
actually were responsible for it's development:
Bill Gates - Computer's Elvis. I fully expect him to die one day while performing some obscure physics experiment (Video Physics lectures are Bill's idea of 
relaxation) and the BBS's (Bulletin Board Systems) of the world will tout his survival in hiding, coding mysterious viruses for decades to come. From a future 
Cover of InfoWorld Weekly: "Gates Spotted in 
Janitors Uniform at Comdex!" or "Gates and Mysterious Alien Fathered My Baby in Bizarre Runtime Experiment." 
He will join the ranks of Hoffa and Hitler. Bill Gates, of course, began and owns Microsoft, the company that provides the premier Operating System for the 
PC, known as MS-DOS. MS-DOS is now in version 6 and has managed the wondrous 
feat of retaining most of the major drawbacks of version 1. Version 1 wasn't written by Gates, it was written by Tim Patterson of Seattle Computing, who sold 
it to Microsoft for $50,000. Bill has made billions of dollars from this 50 grand investment, and Tim Patterson now works for Gates.
IBM Small Systems Group - First, it is important for you to understand that IBM doesn't WANT PCs to be great. They 
want them to be adjuncts to RISC and Mainframe Computers. Every advance in PCs makes another hundred Mainframes obsolete. IBM makes 
a hundred bucks or thereabouts on each PC sold. They make mega thousands installing and supporting each Mainframe (an average 70% 
Margin).
Way back in the 1970's (a millennium in Computers), IBM had made a few attempts at coming out with a personal 
computer. As stated above, it was a project that they were, by it's nature, at odds with. Couple that with, according to many, the IBM way of doing business, which 
is that the Corporation, not the product, is the goal; forming the right committees 
and wearing the right tie are business objectives - putting a product out to market is a necessary annoyance. Having no great enthusiasm for the project, some IBM 
committee that was under pressure to produce a progress report gave Boca Raton an ultimatum: produce a PC within one year or perish. Perish in IBM parlance 
means that your group will be broken up, you 
will have a less than perfect performance review, and you will have to move again. IBM = I've Been Moved. Since no right thinking person wants a poor 
performance review, these stalwart men hitched up their gray trousers, straightened their striped ties, and went grudgingly about giving the world a PC. Certain 
of it's failure (real computers are mainframes, after all), the group was even allowed autonomy; having autonomy at IBM is akin to eating pork on a Muslim 
prayer rug. Unencumbered by the usual IBM flowcharts and Business Plans (spending six months designing a fancy report with all the 
right typefaces and just the right amount of linen in the cover telling everybody what you are going to do just as soon as you finish writing this plan) the Boca 
Raton'ers (between the golf course and the Fifties Dance Committee meetings) decided 
that  since there was no way to produce the proper paperwork AND design a machine in the allotted time, that they would build the machine from already 
produced parts and use their time how they knew best, having meetings. Well, they still needed an Operating System. No one in their right minds at IBM was 
going to give one line of code to these upstart lepers. "Can you imagine! I spend my whole career producing software code that adds leap year day to Payroll 
Accounting Run Modules on the IBM Big Mama VII, and these outcasts want me to write an assembly routine for a desktop toy! The nerve. I got just 7 
months to keep my nose clean and I'll be a grade 8b, which means that Mary can get that Sun Porch she's been dreaming of. I'm not risking my Career 
Development Path for those bozos. Just thinking about it made me late for lunch. Now all the Big Blue Plate Specials will be picked over."
So the Boca Raton Merry Men set off on a quest to find an operating system, much like Bilbo Baggins set off to find the King Under the Mountain. They met 
many colorful characters along the way and had many adventures that they faithfully 
set down in their Daily Planners. Although they had no trolls to fight or elves majik to light the trail, they eventually reached the Western Shores and what 
they hoped would be the end of their quest. The IBM'ers needed a 16 Bit operating system, and the alchemist who held this secret formula, called CP/M, 
(Control Program for MicroComputers) was supposed to meet with them on his magic mountain. Our heroes in Navy Blue arrived at the appointed hour, with 
their famous disclosure document in hand. IBM had (or has) a curious document that we can call the "Playing with the Big Boys 
Agreement". It states, more or less, that anything they learn from you can be used as if they had thought of it; anything you learn from them you must keep secret 
forever. A Magic Scroll indeed! Well, it seems that the owner of the Secret Formula was off flying around the countryside in his private plane that he bought with 
money made from the Digital Corporation (remember the Rainbow, old timers?), it being such a fine day and all, and his wife, who was relegated to keeping both 
feet on the ground, or at least on the desk and to answer the phone, consequently wasn't in the mood to sign anything. It was 
still too early for lunch, so the Big Blues flew north to cry on the shoulder of  Bill Gates, who with his partners in Nerddom wrote Programming Languages for 
various PC upstarts. Bill and his partners had gained fame by writing a program on 
streaming paper for the Altair, arguably the first PC, which not only added 2 + 2, but actually came up with the answer 4! Bill "knew of somebody" who had 
written such an Operating System, called PC-DOS. He promised his best efforts to secure it, handed out Kleenexes and lint brushes and the boys went home 
happy. Gates' minions promptly called Seattle 
Computing and bought PC DOS 1.0 for the famous $50 grand. By the way, Gates was furious at this spending of hard earned capital. PC DOS was 
now owned by Gates 'n Co., and licensed to IBM. IBM has the only rights in existence to market their own version of MS DOS called IBM-DOS 
(currently version 6.1). In classic IBM, it doesn't work and is 
overpriced.
The third and final puzzle piece was the code to hook the off the shelf hardware and the bargained for software together; called the BIOS (Basic In Out 
System) which was produced in house (good for you, boys!) and burned into EPROMS. The 
IBM PC was born, everybody got good performance reviews and... you guessed it, were moved to other groups. Bill became 
a billionaire, Seattle Computing has sued Bill, Bill hates IBM and you and I got some good, if not great hardware and some bad, but not terrible software out of 
the deal.
The Steves, et al
Steve Jobs and Steve Wozniak built a computer in their garage to show their friends in the local computer club how cool they were. They called it an Apple. 
Their friends thought it was way cool so the Steves decided that building lots of Apples would be more fun than flipping lots of  burgers. Now these guys had 
good business sense; they built a good product, kept the trade secrets to themselves, hired good people, paid them well and kept them happy, and totally and 
miserably failed to capture the PC Market. Clear?
Why didn't they call it the Burger? Why am I telling you all this? Do you care? Well, whether you do or not, you now understand the most important concepts of 
the IBM Architecture.
and an honorable mention to:
Lots of folks deserve mention here, but the one that must be mentioned is  Mitch Kapor; Mitch made computing worth the money by making sure Lotus 123 was 
on as many desk tops as possible; without the spreadsheet, there is no way that the Desktop PC would have been justified as a necessary business expense; the PC 
would have given way to the Word 
Processor. With Lotus 123, businesses saw a way to make every accounting type account faster and make more money. 
Letters don't make money because they are on a PC, but numbers do. Mitch got out of Lotus years ago, and now he's doing a little thing called the Internet, which 
will do for the Modem what Lotus did for the PC.
The PC is Born
The IBM PC Clone is a machine that exists because IBM used off the shelf parts that anybody could buy, and, in order to 
get it to the Market on time, used an Operating System that wasn't exclusively theirs. The world, therefor, was given, quite by accident, the most incredible gift 
since the Internal Combustion Engine. A personal computer in a Free Market. Had 
Boca Raton been given the proper time, direction, funding and corporate belief in the project, they would have produced an IBM only machine, captured a small 
percentage of the Market, and you and I (or at least I ) would be shut out of freely participating in this technology. The IBM would have been another Apple. You 
need memory for an Apple, you go see an Authorized Apple Dealer, who tells you that you can pay the price or stuff it up your floppy. You need memory for a 
Clone, you go to a Computer Show and let the dealers yell each other's price down till the profit margin is as low as the dealer can go and still go home with 
Cookie Money, and you buy your memory at fair market price. Excuse me for being hokey, but 
this truly is the greatness of America.
What if each automobile needed gasoline mixed exclusively for that car? What if you had to go to Ford every time you 
needed Ford Gas? Cars would belong exclusively to the rich. Automobiles and Computers have lot in common. Don't get me started.
That ends your Introduction to Personal Computers. I'll bet I'm the only writer you have ever read that has the ability to digress before he progresses.
An overview of what you will learn:
Here is the copy of an actual computer ad. Below it is a quick and dirty summary of what the jargon means. Reading this book and referring back to it will 
make these ads make sense to you
VESA LOCAL BUS
486DX2/66 MHZ
80486DX266 CPU
4MB RAM plus 256K Cache
1.2 and 1.44 FDD
210 MB IDE HDD
32bit VESA Local Bus 1 MB
14" SVGA Monitor .28DB 1024 x 768
101 Key Keyboard
DOS 6.2 (or 5.0), WIN3.1, Mouse
Pentium Ready!
80486DX266 CPU - This computer is based on an Intel 80486DX CPU chip (the heart of the computer) which has been doubled from 33Mhz (it's rated 
speed) to 66Mhz, but only for internal operations (it won't make your hard drive or video run faster). This is currently "top of the line" reasonable for 
home systems.
4MB RAM plus 256K Cache - There is 4 Megabytes of Random Access Memory built in. DOS uses the first 640K (64/100 
of a Megabyte) for programs, the next 360K for loading programs high (out of your way) and 3 Megabytes of XMS (which smart programs like Windows 
use to hold stuff in extended memory while you aren't using it). 4 meg is OK, a bit skimpy for a 486DX. 256K cache is a memory speeding scheme. Certain 
operations which are in line for the CPU to work on will stand in line in the Cache instead of in main memory - which is hence freed to do other stuff.
1.2 and 1.44 FDD - 1.2 Meg capacity 5 1/4 inch floppy drive and a 1.44 Megabyte capacity 3 1/2 drive
210 MB IDE HDD - A 210 Megabyte Hard Disk Drive, used for storage of programs and data. A megabyte is 1,000,000 
bytes. A byte is akin to a word in a book. 8 bits make up a byte. A bit is akin to a letter in a word. (OK, OK, so I'm simplifying...) 1K is 1,000 bytes. A 
page of text is about 1K. 210 Megabytes is 210,000,000 bytes. Windows takes 5-10 Meg of hard drive space. 210 Meg is a good size drive. IDE is the 
"format" of the hard drive - stands for Integrated Drive Electronics. This is the current standard. High end systems will have SCSI drives, and used systems 
will have MFM or RLL. IDE is fine.
32bit VESA Local Bus 1 MB - The Video Card in the system is VESA Local Bus - It has three connectors at the bottom. 
The first connector is 8 bit (OK for a serial port card) , the second is the 16 bit connector (OK for normal AT class cards) and the third, extra connector  is 32 bit, 
which gives it priority with the CPU. It doesn't have to wait in line behind the floppy drive formatting a disk. It communicates with the CPU directly. This board 
has 1 Megabyte of Memory of it's own, 
so that the image going to the Monitor is pre-processed so the CPU doesn't have to do it.
14" SVGA Monitor .28DB 1024 x 768 - This is a 14" (just like your TV is 20" or 27") Super Video Graphics Array Color Monitor. Super VGA means it shows 
lots more colors and lots more information than standard VGA. The difference 
between a color picture in the newspaper and an actual photograph. 1024 X 768 is the maximum resolution - there are 1024 pixels (dots) across the screen and 
768 dots up and down. There is more information and colors than you would have at 
standard resolution, 640 across and 480 up and down. .28 is the dot pitch - the smaller the dot pitch, the clearer the picture. A .39 Monitor will ruin your eyes. 
Everything appears cloudy.
101 Key Keyboard - BFD. All keyboards that meet standard for 80286 and up are 101. This is akin to Ford saying all of it's cars are equipped with a 360 degree 
round steering wheel.
DOS 6.2 (or 5.0), WIN3.1, Mouse - They are providing the operating system - MS DOS version 6.2, the latest, or, if you are one of those ninnies who hates the 
latest and greatest, they'll give you 5.0; they are also providing Windows version 3.1 and a mouse.
Pentium Ready! - means that you can swap out the 486 chip with a 586. You won't want to. Trust me. Would you swap out 
the 4 cylinder engine in your 1989 car for a 1994 8 cylinder engine or buy a new car?
All of the points above are covered below in much more depth.
SECTION II - IBM Compatible Hardware
The Machine.
Evelyn Woodhead Speed-reading Disclaimer.
Some of this stuff you are already going to know. You have my permission to skip ahead any time that the material is too basic for you. The intended reader of this 
trash can be someone who is too embarrassed to ask the really basic questions. 
The following will assume that you intend to build a computer. If you are upgrading or just learning, the information is still just as valid.
The Basic Parts 
There are a number of items you will need to get started and they are easily obtained.  All compatibles have the following components: 
*A Case  
*A Motherboard (w/CPU and BIOS)
*A Power Supply  
*A Keyboard  
*A Monitor  
*A Disk or Hard Drive (I/O device)
*ROM [Read Only Memory] -the basic 
instructions *RAM [Random Access Memory]- 
your work space  *Controllers
The more useful options are:
A second Disk Drive or a Hard Drive;

a Modem;
a Mouse;
a Printer. 
The extras include
a Sound card
a CD ROM
Stereo Speakers
A scanner
PREFACE
This article started at 5 pages. It is turning into a book. That's good in that I'm passing along lots and lots of information that will save you days or weeks of trouble 
and lots of dollars. It's bad in that the technical jargon may turn you off. It shouldn't. The actual building process is something you absolutely should be capable of 
doing. Here is a one paragraph summary of what you will be doing:
You will buy a case, install the motherboard and set a few jumpers per the documentation. You will fill some empty sockets with memory chips. You will put in a 
little silver box that is your power supply. You now have a computer. You will next insert a card into a slot and hook a monitor to it. You will plug the keyboard 
into the back. You will plug in a card which controls the disk drives, and hook the drives up. You will turn on the machine and tell the computer about the stuff you 
have added. That's it. Really. The balance of this article is to help you decide which monitor, drives, etc. to buy, and then gives lots and lots of advice for 
avoiding pitfalls along the way. Each of these pitfalls caused me heartaches and headaches. I pass the solutions on to you so that you may avoid the problems. 
There will, in all likelihood, be a debugging period. This 
is normal for any high tech project. You very likely will not get every jumper right the first time, unless you are one of those people that seem to be born with a 
horseshoe up the butt.
If you want to cut to the skinny, here is a short list of the parts for a recommended system:
You may, for $500-700, buy the following in one morning at a computer show-
A baby tower case with power supply, an 80386 motherboard, 2 meg of 1 Meg chips (18 chips) or 2 SIMMS, a 512K VGA 
Card, a Mono VGA monitor, a hard floppy controller, a 5 1/4 and 3 1/2 disk drive, a used 20 meg hard drive and an AT compatible keyboard.
Do it your way and to solve the problems as you go along. It's just a logical process.
I have assisted many, many people in building machines, and there are basically two types. The first takes my advice, begins the building process, and takes the time 
to read and develop the common sense knowledge necessary to finish this project 
and learn a heck of a lot as they go. The second group wants me to be their brain, build it piece by piece for them, and never crack a magazine or a book. I'll say it 
just one time: YOU HAVE TO READ TO GET ANYTHING OUT OF THIS 
PROJECT. If you do, you will be AMAZED at how easy it is. 
Step One
Buy a Magazine!  (!?!)  An indispensable tool is Computer Shopper Magazine, published Monthly and available 
everywhere.  It lists the CATALOG prices for everything you need, in all the various options.  If you have three weeks to wait, you will get the absolute best prices 
on whatever new and current you want (see Computer Shows for the exception).  Otherwise, you will have the basis for comparison for shopping elsewhere.  A 
general rule of thumb: 
Catalog prices are 
- 40% Lower than Discount Store Price  
- 60-80% Lower than Computer Store Price  
- 10% Higher than Computer Show Price 
there will be exceptions, of course.
Example: 1 Meg 70 Nanosecond RAM Chips  
Computer Store- $20 each 
Warehouse Store- $12 each  
Catalog- $4 each  
Computer Show- $3 each 
Spend an entire evening reading this magazine cover to cover- it is equivalent to an entire College Course in 6 hours.  Your head will be stuffed with new 
information and insights. 
A Brief Description of Your Buying Options; advantages and disadvantages. 
Computer Shows  
Held around the area by different Companies- watch the local paper Business Section and the back of Computer Shopper Magazine. Careful buying is the 
watchword.  Buy all your Cables and miscellaneous parts here. These shows are getting harder and harder to find. It's getting too tough to make a profit. It is 
ABSOLUTELY worth a 60 mile drive to buy at a show. You will be in an environment where if a product can be sold at a $2 profit for $20, Harry will 
undercut Chen and sell it for $19.
Ask lots of questions about other pieces from information you gleam here, from Magazines, and from Books you run across.  Knowledge is Power.  They 
will mislead you to make a sale- but won't make any patently false statements.  My purchase of a 3 1/2 Disk Drive was a great buy until discovering from the 
Panasonic Technical Department that it won't run in Motherboards made after 1985!  But the Dealer mailed me a refund. Do be careful and do plan to fight 
someone who doesn't want to give you a refund.
Catalogs 
As stated before, the main drawback is the wait; and don't forget that you have to add shipping and handling costs to the price.  Invest the dollar to call the 
Advertiser's Technical Line and ask questions: is this Hard Disk Controller MFM or 
IDE? Is it 8 or 16 bit?  (don't get thrown by this jargon- you will learn it quickly.  It's analogous to asking Is it Front or Rear Wheel Drive?  4 or 8 Cylinders?  Someone 
who never drove a car would be just as thrown by those questions.) 
I have had a real nightmare dealing with a Mail Order house in Texas. We were up to 4 bad shipments before we called 
Computer Shopper, who laid down the law to the turkeys. An exasperated president called the day after we called Computer Shopper and said "What do 
you want?" We told him, and we got it. Air Freight. Free. Most houses in Computer Shopper 
are very reputable. Just be careful, and call the tech line and ask lots of questions. If they have no time for you, you have no money for them. Do remember, though, 
that the parts are cheap because they are operating at a small margin. Don't expect 
them to spend the day teaching you how to build a computer. 
Discount Store  
Some Discount Computer houses need careful watching, too. We have a local dealer whose prices can't be beat, but the 
product he sells to schmos like you and me are usually the parts that didn't work when he put them into a system. He sells them over the counter because it's 
more time effective than troubleshooting the part. He knows that 75% will come back, giving him an easy RMA and the buyer will figure out what is wrong 
(wrong jumper, bad partitioning) with the other 25%. So he gets free troubleshooting.
When buying a piece that may take two or three times to install right- such as a Disk Drive- the extra money to buy from a local store may be worth it. 
Questions like which pin is this jumper set on to make this Drive B and High Density? is tough to answer AND make a profit if you are a Catalog Dealer.  
Make your decision based on how comfortable you are installing the part.  The best source of all is the sales and repair place you now use for work.  Making 
friends with your Service Rep gets you into the back room- where all the Used but working Parts are kept (and can be bought!!) Where do you think all the parts 
went when you upgraded your AT to a 386 at work?
Computer City, a division of Tandy (yeah, Radio Shack) does a decent job at generally decent prices. But it's not the place to buy parts. If you decide to give up and 
buy a system, this place is not the worst. But buyer beware! Make sure you have read this article thoroughly and know what to look for. A better choice might be a 
medium sized chain like PC Warehouse, who 
has yet to give me a bum steer.
Computer Store  
BIG Companies get BIG prices having slick salesmen who frown knowingly at your questions.  They don't want you to buy 
a part-they want you to buy a System. 
Your first buy:
The Case 
The XT 
An XT style Case  Allows for an 8088 based Motherboard or a Baby AT- most motherboards will fit in here. It will also fit all ISA components. If you want to 
make this a long term learning experience, this case can't be beat for being easy to get "under the hood". The ultimate is a "flip top" XT style case.

The AT Case
The "true" AT Case has become a dinosaur. It's a BIG case designed for an AT size Motherboard. Almost every 
motherboard I have seen in the last year fits into a Baby AT configuration, and the new AT size cases have provisions for fitting a Baby AT board. You would 
want to pick this case if you have saved money by purchasing a full size hard drive that will not fit with two drives in a smaller case.
The Baby AT
(Aw...isn't it cute??) Uses a Motherboard sized to fit in an XT size case.  My original choice.  Most AT parts (except a full size Motherboard, full size Power 
Supply (XT size) and some 16 bit cards fit in here.  Takes less room, just as fast. 
Absolutely DO NOT BUY "ultra slim line" and such cases. If a standard peripheral won't fit, you are headed in a woefully wrong direction. I have recently seen 
some jet black systems. They are now available to be bought case only. Why are computers white?. Why not paint the case mauve? What do you care? S'matter of 
fact, I recently did that. Painted my case 
my fav'rit flava, cherry red. Looks cool. You still don't care.
The Tower
A case for those of us who spend extra for a Turbo engine in our car. Sleek, elegant, and powerful looking. It stands vertical instead of horizontal. The Power 
Supply is usually bundled with the case. You can achieve the same effect (mostly) by 
buying a $6 stand at a show. There are two types of Tower cases; those that have to be taken apart like a standard case (i.e. 6 screws in the back) and those with a 
removable side panel that allows access to all peripherals with the turning of two large screws. This panel makes the IBM PS2 80 a dream to work on.
The Baby Tower
This article just keeps getting longer. This item is practical and pretty reasonable priced. I picked mine up with power supply for $129. They now go for about $45-
60.
Expect to pay $25-80 for the case, up to $125 for a tower case with Power Supply. Buy with confidence from a computer 
show or catalog.  Hard to mess this one up.  Look for panel lights, a key lock, and a flip top (wish I had one!).  You are inside this babe 30-40 times while building, 
tweaking and adjusting, and a flip top will make your life easy. The "digital 
display" on some cases is incredibly hard to configure for the novice. Save this feat till later if it looks intimidating. Brush up on yer binary math.
The PC HELP pick: The Baby AT Tower with removable side.
In any event, the case must be large enough to handle standard add in cards. If it won't, you got problems.
Installation
Install the small speaker and LED's (light emitting diodes) and lock, if any, on the case.  The speaker may get annoying.  It is loud.  Radio Shack can help you install a 
little switch to turn it off and a headphone jack for private listening of the annoying beeps.  (This is where I used the soldering gun). You need to mount these so that 
the wires don't pull out when 
you remove the case! Save this operation for last if you are building all at once. It only becomes important in the long run.
What are all those damn wires in the case??????
Don't Panic. Here's an overview of the most common.
Speaker: Two wires coming from the speaker. Terminates in a 4 hole socket. The two wires will hook up to the "speaker" 
pins on the Motherboard. Plug this in even if you have a sound board to be added at the end of building. Reverse the wires if you don't get a beep when you turn on the 
machine. You may have to modify the four hole socket or move a wire to make 
the speaker work. This can be frustrating. Two little tiny alligator clips hooked up to the speaker wires and run directly to the pins on the Motherboard may be the 
easiest way to debug this.
Reset: Two wires that plug into a set of pins by the same name on the Motherboard. The pins may be located back by the keyboard  connector. Why? I don't know. 
Ask somebody else. This is what will cold reboot your machine when you push the 
RESET button on the case.
Turbo: When you push the turbo button on the case, your machine will toggle between high gear (say 33Mhz) and low (say 25MHz). Plugs into a set of 
pins by the same name on the Motherboard. You will want to be able to slow the machine down when you are trying to trap an error.
Turbo LED: Two more wires. This will, when wired properly, light up the Turbo light on the case when the machine is in high gear.

KeyLock: This may be in combination with the Turbo button above. Allows you to lock out the machine with a key. Also 
plugs into the Motherboard.
Hard Drive LED. This is usually plugged into your hard disk controller to blink whenever there is hard drive activity. You will eventually depend on this light to 
tell you when long operations are actually proceeding when no other activity is apparent. Also lets you watch for "thrashing". If the hard drive light is constantly or 
near constantly flashing when you are at work on the machine, the machine may be desperately trying to keep up with the workload when memory is low by 
copying unused in memory stuff to the hard drive to make room in conventional memory. It means either
*       You need to install more memory    or 
*       Your machine is not configured well. Becoming a smart user is learning how to tweak your machine to make it run smooth. Just remember: if your hard 
drive is thrashing, a power outage could be a disaster.
Two large white plugs and five or more medium size white plugs. These are the leads from your power supply. The two 
large ones hook onto the Motherboard, sending main power to the system. The five or more  smaller ones are the power for internal devices such as disk 
drives, hard drive(s), CD ROM, etc.
The Motherboard 
Now you have a real decision to make- once you make it, you have decided on the basic Architecture of the Machine and there is no turning back. You now 
need to decide whether to buy a 8088, 80286, 80386DX, 80386SX, i486DX, i486SX i486DX2, Pentium (80586) or one of the new clone CPUs. Buy with 
or without Local Bus. Buy with or without Cache. 
Don't worry about the Motherboard being "Pentium Ready" or "DX2 ready" or such nonsense. When you are ready for a new CPU, you will be 
ready for a new Motherboard. Trust me. Many Manufacturers of Motherboards..  Buy whichever one you choose with the highest MHz rating you 
can afford. 
Saving a few dollars by buying an XT board will limit you to a non-reusable keyboard (unless it is switchable) and hard disk controller, a hard to replace BIOS, 
and no Windows 3.x or other newer software. As of this article, we also say good-bye to the 286. This old workhorse has not become obsolete as much as the 
price of the 386 plunging to the point that it's silly to buy less. Go 386DX at least.  The time has come, folks. The world needs to move on. The new lowest 
standard will be 16 
Bit 80386 technology. So don't waste yer money.
INVEST in the Motherboard.  Spend the extra $20-50 to get the best you can afford.  Skimp on the replaceable. 
Mini Glossary
At this point, we need to pause and give some thumbnail definitions to a few buzzwords. Read up on them if you want to understand more.
Mini Glossary # 1
CPUs
8080 - The original Intel CPU. Pre IBM. 8 Bit. CP/M operating System
8086 - 8088 - The original PC and XT. About 4.77 MHz. Turbo at 8 MHz. 8 bit. (8087 Math Co-processor)
80286 - The original IBM PC-AT 10 - 15 MHz. 16 Bit with eight bit functionality. (80287 Math Co-processor). Cannot use 
XMS memory. Wastes resources.
80386 SX - Crippled 80386 Chip, supposedly upgradeable to 486. Yeah, and you can upgrade a fart to a methane power 
plant, too, but it's still just an exploding fart. (80387SX Math Co-processor).
80386DX - Bill Gates wanted IBM to use this chip in the AT. Made too much sense. 20 - 40 MHz. 16 bit with 32 Bit 
access. Nominal standard. (80387 Math Co-processor)
80486DX A chip way beyond MS-DOS and it's limitations. 33Mhz to 50 MHz. Faster than everything else in the system, basically sits around a waits for 
something to do. Has a "C'mon, do something" attitude. Windows NT supposedly will break the stupid 640K limitation and use this chip for real work.
80486SX A 486 with the Math Co-processor disabled. Like a four slice toaster with two openings covered over.
80486DX2 - Has a speed doubler  (or halver, depending on your outlook) that allows for some operations at say 50 MHz, 
and the rest at 25Mhz, it's true speed. I think it's the OS/2 of Motherboards.
Pentium - The all new, improved CPU from Intel released in 1993. Intel and Microsoft Marketing have a lot in common 
with the Auto Industry. Put out a product just a little better than the last one, and six months after you tell the public that the one AFTER this will be really great. The 
p6, of course, is well on it's way. Why isn't it called the 586? Intel found out in it's court battles with Cyrix and AMD that the number "486" cannot be properly 
protected as proprietary. It will be much 
harder for Cyrix to get away with putting out a Cyrix Pentium than it would be putting out a Cyrix 586.
80286,386,486,286SX,386SX, 486SX Clones. AMD and Cyrix and some other guys are making clone CPU's. Be careful! They have played 
games with the numbers in the past. Make sure that 486 is really Intel 80486 compatible.
The 8088 (XT) Board
Somewhat slow but can be made faster depending on options and speed up boards.  8 bit technology.  For The Person Who Has Lots Of Time To Wait 
for Spreadsheets To Recalculate.  The technology is now as pass_ as Leaded Gasoline. Not recommended. Analogous to buying an Atari 2600 (lots of 
cheap programs around!) rather than a 3DO game system.  Why buy something that will be expensive to speed up?  Operates at 4.77 MHz, with most 
Motherboards now being "Turbo" (8 MHz). Most DOS based resources are downward compatible, though, and you certainly can build an XT for a 
truly economy minded system. Just don't expect to do any real work. 
Consider this: The 8088 Motherboard can be had for less than $80. IF you go this route, you need to know if it can support high density floppy drives. If it 
doesn't, you will be limited to low density floppies. Upgrading an older BIOS XT to run these drives and to support VGA Monitors will cost you $49 from the 
Catalog. Plus $10 shipping, handling, postage, etc. $80 + $49 + $10 = $139. Cost of a 286 Motherboard: $50. You may be getting the impression by now 
that I am trying to talk you out of an 8088. You got it. 
The 80286 Motherboard
The easiest to get cheap prices all around. Is becoming a dinosaur. Look, if this machine is going to be used for anything besides games (even mine is used 
otherwise), go 386sx and up. Choose he 286 option if the machine is to be built mainly from used parts. They are everywhere. Don't expect to run Windows or 
anything serious.
The 386DX and 386SX
The lowest level being supported "for real" in the industry. Very, very fast compared to 286. The minimum way to go- the 
price is coming down every day. 
Many people I have spoken to advise against the 386SX as being a step backward, and that a fast 286 will beat up a stock 386SX. The other side of the debate is 
for the pauper poor builder, the SX has the technology on-board to keep it from becoming pass_ when developers bypass 286 technology. The 386SX chip is 
supposedly replaceable with a 486 chip. I don't believe it. A Porsche engine could conceivable be crammed into a chevette body, but who would want to make a 
turn in that baby at 110 MPH? The hardware to make it purr just ain't there. If this machine is going to be useful when DOS goes byebye, 386 will keep you in 
the race at a price a bit lower than 486. Motherboards for the 386DX are currently show priced at $79. These boards are getting harder and harder to find.
The 386DX is a true 32 bit machine, albeit with 16 bit boards. Get a cacheable board. It's another of the tips and tricks employed by hardware manufacturers to 
speed up their main boards.
The i486
.Just starting to really come down in price. The price was kept artificially high for two years or so while Intel was fending off competition. Right now, the 
Motherboard with CPU is selling for around $399. Expect the price to fall to around $200 in 1994. The 486SX, which is a 486DX with the co-processor disabled, 
can be had motherboard and all for about $179. This is the current "best buy".
486DX2
Ai Caramba! Just what the average Joe User needs... another CPU spec. Ok, you got yer 486SX, which is a 486DX with no 
Math Co-processor. Now you got yer 486DX2, which employs a clock speed doubler to make a 486DX25 run like a 
486DX50. That is, inside the CPU Mondo Condo, Danny Data and his friends are partying at 50 MHz. Danny discovers 
that he needs to go out for more beer. He opens the door and steps into a world running in slow motion (25 MHz). He rides 
a 16 bit data bus just like the old folks. Danny has to wait in line for beer just like the rest of his 386 friends. He even has to squeeze through some 8 Bit cards to get to the 
store. (Danny's a 32 bit kinda guy). He goes home, and from the moment he 
passes the doorman and through the revolving door, he's partying at light speed again. Which just makes the beer go faster, 
I guess.
The Pentium
For those of us who just have to know the last digit of Pi before dinner. (Pi should be saved for after dinner. Sorry). Pentium systems are just coming into mass 
market; wholesale prices are at about $2750 without monitor but with Local Bus. The 
Pentium was made to compete with SUN Microsystems and Mainframes. It uses technology the PC will never ever use 
while running MS-DOS. Pass.
The PC HELP pick for December, 1993: The 486SX-33 with 0/1 WS, 128K cache, VL Bus. Pay $179-249 based on 
features.  Buy from the Catalog. The latest system I helped build had made enormous strides over just six months ago.
Time out: A word about the BIOS
For whatever board you buy, you must be aware that next to the actual processor the most important consideration is the 
BIOS, so it deserves it's own blurb.
The BIOS (Basic In-Out system [ooh baby])
Three chips, two for the machine and one for the keyboard. Look for BIOS built in ($50-100 to add, AND there very well may be compatibility 
problems mixing and matching), the word NEW in the Ad (you don't want something made in 1988; the BIOS needs to be able to work with Multimedia 
and Caching).  A good question to ask: Does the BIOS support DOS 5 
hard drive partitions? Is there a User Configured Hard Drive Type? What is the date of the BIOS? The "main instructions" to the CPU are handled in these 
(usually two) chips. Award, AMI and Phoenix all make BIOS chips, and they upgrade them constantly. Mr. Mail Order is all too happy to unload a 
Motherboard with an old BIOS to Mr./Ms. NewBuilder. I'm not an expert on BIOS chips, but will pass along that American Megatrends (AMI) is my BIOS 
of choice, and produces (or has produced for them? I don't know which) special BIOS made in cooperation with Chips and Technology (C&T) that come in 
two flavors- EC&T which has extended BIOS settings for the true nerd and DC&T with diagnostics routines built right in. Just don't try to get tech support 
from C&T. The power and options of your BIOS can make your life easy or unbearable when you go to upgrade.
The BIOS was a development that happened in the early days of PCs. Since all IBM parts in the IBM PC were off the shelf, the machine itself was easy to 
duplicate. The Operating System, bought by Bill Gates from Seattle Computing for $50,000 
and re-sold to IBM and everybody else to the tune of $3 billion or so (nice ROI, Bill!) was no problem to get. It was the part in between that was tricky. Making the 
machine talk to the software. IBM had that sewn up in their own little hardware scheme, so some enterprising nerds had to go and write the interface and burn the 
instructions onto chips, called the BIOS. The first, second and third attempts were less perfect than DOS 4.0 or the IBM PC, Jr., believe it or not, and it has taken 
them years to get it right. Get a BIOS that identifies itself at boot up time as being 1991 or 1992. DON'T buy a Motherboard with a BIOS dated (not on the chip, in 
setup!) as being from the 1980's. Buy it only if he will give you a $45 allowance towards new BIOS chips. The PS2 line of IBM needed a "set-up disk" to get to the 
BIOS. Every time you added an option, 
and option driver had to be added to the set-up disk. Most IBM owners don't have the foggiest idea where their set-up disk is. COMPAC and IBM have now 
both gone to on board BIOS set-up. Please know and be able to tell the technician how to 
get into setup for your BIOS. Not knowing makes you look really,really dumb. It is usually a key combination that you press during boot up; on AMI it is 
usually (ESC), on Phoenix (Ctrl-Esc), on new COMPAC's it's F10, etc.
Installation: 
The Motherboard fits into the case with screws and set-offs.  Very easy to assemble.  Many Motherboards come with instructions. My first one didn't.  If not, 
take out of a library or buy a book, such as How to Build an IBM Compatible and Save a Bundle by the late Aubrey Pilgrim.
After putting together many of these things, here is my recommendation for how to proceed. place the Motherboard on a towel. Follow the manual if you have 
it and set the jumpers and dipswitches as you think they will end up. Decide where each connector (Turbo LED, Turbo switch [don't confuse the two], power 
light, reset, etc.) is going to be hooked. Install Memory, filling Bank 0 first. Put standoffs on Motherboard. Slip it into the case a few times on a trial run before 
you commit. NO drives or other peripherals should be inside the case yet. You need unobstructed room. When you are satisfied that the board is oriented 
correctly, slip it in and gently move it around, letting the standoffs find the proper holes. 
Handle this Baby with CARE (the Motherboard, not the book.)  LEAVE it in the plastic wrap till you are ready to install. 
Put the little white plastic set-offs on the board, not the case. The white standoffs will slide into keyholes on the case; gently prod them around until they are all in the 
keys, then work the Motherboard gently down into the case. There will be one or 
more places for a screw to attach the Motherboard to the case. If the screw fits right in, the Motherboard is properly seated. Touch the Metal Case before touching 
the Board. Practice inserting the Motherboard twice before actually putting it in. Visualize how it is going to slide in. Don't mess it up here! 
On Getting Fried
Now is probably a good time to talk about Electrical Safety. I wish I had a black and white classroom newsreel with  a 
bunch of dweebs in Hard-hats to show you, but Multimedia presentations are, at this point, still mostly baloney. So, you'll just have to read this. PC Computing 
consists of 5 and 12 Volt circuits. Taking a full jolt from a Video Card can hardly be felt. Don't worry about getting shocked working on the computer unless 
you do something very, very dumb or you are very, very unfortunate. You can, however, by not being careful damage the components. The only three places I 
can think of that you are likely to get fried are
1) Sticking your hand inside of the Power Supply - that would involve getting past all kinds of safety stuff. Don't do it.
2) Opening a Monitor Case. Don't do it. There is lots and lots and lots of pain and possible death waiting for you in the back of a CRT. I make my brother open 
monitors.
3) Sticking your tongue or some damn thing in the power cord. Don't do it.
Turn off and unplug the Computer before working inside.

LEGAL TYPE DISCLAIMER FOR THE ABOVE PARAGRAPHS:
Because I tell you it is very hard to get shocked working on a Computer, that doesn't mean you can't do it.  Some fool will always find a way to get around safety 
precautions, get themselves hurt, and sue somebody. I am not responsible for injuries, damages or monetary losses due to use of the material in this article. Take 
all proper and reasonable safety precautions.
Plug the Speaker leads and the Power/Turbo LED's on the Motherboard as indicated. If they don't work when you fire it up, reverse them. Set the jumpers per the 
instructions. Pick 0 wait state if your chips are LESS than 100 Nanoseconds (you'll read about them later). Read slowly and carefully. It all makes sense. No, you 
probably don't need a Math Co-Processor. If you don't know what difference changing the jumper will make, don't change the jumper. There are lots of jumpers 
on lots 
of cards that are already set for IBM Compatible machines. Changing the jumper could change the I/O address, change the voltage input from 5 volt to 12 volt, 
or a hundred other things. Don't flip a jumper if you don't know what it does.
MCA (Micro Channel Architecture)
 .
IBM wants yer money. They came out with Micro Channel for two reasons: 10% to improve the computer, and 90% to 
destroy YOUR ability to build your computer with inexpensive, readily available parts.
Ignore it, and maybe it will go away. Makes every card you bought Useless (notice the capital U) by changing the socket that fits into the Motherboard. Boo Big 
Blue.
ISA,EISA and MCA
ISA is Industry Standard Architecture. If you buy parts and build a system that is ISA, you will be a happy person forever. Or at least a reasonably close 
facsimile. Make sure your case is big enough to hold the Motherboard, standard expansion cards and drives. Make sure your Motherboard has plenty (5 or 
more) expansion slots. My machine has A hard/floppy/I/O 
IDE Controller, an Internal Modem, a Fax Board, a Scanner Card, a Video Card, a Tape Backup Card, a CD ROM Card 
and a Soundblaster. That's eight slots right there. EISA is a newer standard that follows ISA close enough that you can use regular expansion cards. MCA 
stinks. Expensive, hard to find components.
Local Bus
This is a new scheme developed by a bunch of Manufacturers that allows Video and/or I/O to directly address the system and output and not have to stand in 
line behind everybody else. Video and Hard Drive access time are your two worst 
enemies. Listen carefully here. It doesn't matter how fast your system is!!! It is how fast the Video and Hard Drive operate. It is said that a system can't exceed 33 
MHz no matter how fast the system purports to be. So pay attention to Video Speed and Hard Drive Speed if you become another Nanosecond cutting freak.
VESA Local Bus and Intel Local Bus had a brief, intense warfare which VESA won. VESA has become the standard for 
both Video schemes and Local Bus Architecture. Most new Motherboard come with local bus, which adds a third slot to standard cards. Here's a 
humble drawing of a Motherboard showing the CPU, the BIOS, Memory, the Power Connector and the Bus slots. This is all you will need to know 
for general knowledge of the motherboard
Those of you with a text only copy of this book will just have to imagine all the cool graphics you are missing out on until you send me five bucks for copying 
and shipping.
Power Supply
For an XT, somewhere around 150 watts is sufficient.  An AT, you should spend an extra $20 to go to 200-250 Watts. The higher the wattage, the more junk 
you'll be able to stuff inside.  For a Baby AT, buy an XT Power Supply with a high rating (200 Watts). 
My choice: A 200 watt XT Supply (fits a BABY AT). I chewed up two 130 Watt Supplies. Buy from a Catalog or Discount 
Store.  Power Supplies are the most often repaired item.  Don't buy it used.  They go up.  Pay $35-55. 
Installation  
Slips into the case via two slots at the front of the supply, then screws to the Case.  Has two plug-ins to the Motherboard.  Make sure the black wires are next to 
each other when you plug them in.  Has 5 or more plugs to go to Drives and such. The little one goes to the 3 1/2 inch drive. Except for that one and the ones for 
the Motherboard itself, they are all the same.  Make sure it comes with a Power Cord!  If not, it's a cheap item ($3 at a show). 
You will be tempted to check your installation and turn it on for a second. If you do, you will hear a series of annoying beeps as the Motherboard comes to life, 
finds no Monitor, Controller, Drive or Keyboard and promptly bails out. You 
should hear a gentle whirr from the Power Supply.  If you see sparks or smell ozone, shut it down (quick!) and start over. 
The Keyboard
May be bought refurbished from a store.  You MUST buy an Enhanced 101 keyboard for a 286 or higher. Old XT's used a different processor, even though the 
connector still fits! The enhanced has some neat extra keys, extra Ctrl and Alt Keys, 
and F11 and F12.  Some keyboards are switchable from XT to AT.  Pay $20 (used) to $100 (fancy extras). Avoid keyboard companies that consist of three letters, the 
first of which is a B. Focus is a good brand. Look for a nice click when you press the keys, LED's for NumLock, Caps Lock and Scroll Lock. If you want a GREAT 
keyboard, get a used IBM. They do make 
the best keyboards for some reason. If you do, you will need to get an adapter to the bigger size clone style plug. Available at most computer stores.
Installation: 
Has a round plug. Plugs into the back of the case. IBM has a little round plug on their PS/2'S, so make sure it's AT compatible. You can get an adapter to make an 
IBM Keyboard work with a clone.
The Monitor
Ok, now we come to some pure decision making.  To keep the as built cost down, consider giving up color.  Just for now.  Trust me.  If you want to really plan for 
the future, though, and want to add $300 that will make you happy in the long run, go for the gold and add a multi-sync or multiscan Monitor. I advise AGAINST 
anything in between.  If you buy something between Mono and Multi, you will have to throw away or trade for next to nothing to upgrade.
The choices are: 
Mono:
Monographic Monitor.  Green, white or amber on a black background.  Does graphics, though!  Don't try to use a TV, even 
if it calls itself a "Monitor". Monitor in TV language means that there is a video out RCA type plug in the back for hooking up to a VCR and such. A TV only does 
40 columns across (characters) and you need 80. A Mono Monitor is OK to get you 
up and running. Otherwise, you will be tempted to buy something less than a very good monitor. Don't. PLEASE don't buy 
a cheap VGA monitor. 
CGA  
Color Graphics.  Also called RGB for Red, Green and Blue.  Shows 4 colors (figure THAT math out!).  Tandy CGA shows 
16.  Nice, but a $200-400 investment that is pass_.  Many graphics programs demand EGA. 
EGA  
Enhanced Graphics.  16 colors at one time.  Was the high end standard a few years ago. Gone and hardly supported. Uses weird Memory addresses.  Go higher 
or Mono. 
VGA  
Video Graphics Array.  Puts a picture of your Mother on the screen.  In blushing color.  This is where you want to be. "Real" VGA is .31 dot pitch or LESS. 
VGA comes in two flavors: analog and digital. In most electronic and audio applications, digital is better than analog. In VGA, it's the reverse. Analog is 
better.   You need EGA or VGA to fully run programs like Freelance Plus (Lotus).  You are almost there. Read on. 
Super VGA
Super VGA is enhanced VGA. Has to do with the number of lines of resolution on the screen. A monitor whose resolution 
is 800x600 is considered Super VGA.
Multisync  
You have arrived.  Will run anything.  Works anything.  $300 for a perfectly good AOC or Morse to $700 (discount) for a NEC.  Check the Catalog.  You can 
find familiar names like Sony and Toshiba here. CGA runs at a certain frequency, as does EGA and VGA. Hence, multiple synchronization. Old IBM's used 12 
inch screens; most Monitors today are 14", with 
15 and 17" available. Go 14 at least. Once you are up and running with Windows, there will be a lot of information to squint at.
Interlaced Vs Non-Interlaced.
A non-interlaced monitor is better. Interlaced Monitors refresh the screen so that the screens overlap, i.e., are laced. This causes screen flicker, something I don't 
care beans about, but it seems to be a big item to some.
Dot Pitch
The lower the number, the clearer the picture. A .38 Pitch Hyundai Monitor looks like there is a milky film over the picture. Save your pennies till you can afford 
.28 Dot Pitch, Super VGA. You need 256 colors to show full color pictures. If you are going to go VGA, it's silly not to be able to see photos in full color. 
PLEASE look at a Monitor's picture closely before buying. There are a LOT of crap Monitors on the market right now. Buy Sony or NEC if you can afford it. A 
good buy is  a refurbished NEC Multisync 3D. Say what you will about Super-VGA, Interlacing, etc., etc., my 2A has a clearer picture 
than some $1000 Monitors I've installed.
Refresh Rate
Higher is better. Mine has a 70 MHz Vertical refresh rate. I think that's good. A high refresh rate reduces flicker.
Until you can afford good Video, consider VGA Mono now, Multisync and VGA later.

Windows Accelerators
The thing with a Graphical User Interface (that a GUI, folks, pronounced Gooey. . .GUI and SCSI, Gooey and Scuzzy, (any shrinks out there?) is that it 
takes a LONG time for graphics screens to change with regular equipment. So some guys have come up with schemes to make graphics happen faster. A 
video board with an S3 chip set (or ATI's Mach 8 or Mach 32 
chip), which should add about $50-100 to the cost of the board, will, they claim, make Windows run 3 or more times faster. VESA Local Bus boards add 
speed to graphics, too; you should only have to have one or the other.
VESA
Another standards committee. When you have an open architecture system like the clone world has, all bets are off that Vendors are going to provide you with 
what you expect, unless somebody is setting the standards. For Modems, it's CCITT, for Memory it used to be LIM. For video, it's VESA, the Video 
Electronics Standard Association, which defines, among other things, Monitor timing for several resolutions at certain refresh rates. The better Companies 
have provided VESA TSR's (Terminate and Stay Resident programs) that allow you to make your old board VESA compliant. A lot of newer graphics 
programs only run if VESA is present. VESA Local Bus is the 32 bit Slot standard by the same outfit.
VGA Calculations
Oh no, more Math! Someday you may be interested in calculating how much Video memory you will need to run higher resolution Video. When you do, dig 
this article back up and read this section.
Pixels n' Color
As opposed to TV, which is measured in Lines of Resolution (don't get me started), Computer Graphics are measured in 
Pixels. The screen is made up of little tiny dots of light, a number of them concentrated with different colors at each Pixel Point. Absence of color is black, saturation 
of color is white. The more Pixels on the screen, the better the resolution (less jaggies, less blurring) and the more possible colors per pixel, the more realistic the 
image. If your graphic sends a signal to your Video Card that Stanley's hat is a distinctive bluish green just a hair lighter than the green on the back of a dollar bill with 
a cast of blue akin to a drowning victim, your 16 color card would yell at the color guns "Yo! Gimme green!" A 32K 
color card and monitor would faithfully duplicate the Dollar Bill-Drowning Victim-Blue-Green. OK? 
VGA Resolutions
Standard VGA is 640 X 480 - that is, 640 Pixels (dots) wide by 480 Pixels high. 640 x 480 = 307,200 Pixels. The third 
number in VGA specs is the number of colors. We add 16 colors, making the Standard 640 X 480 X 16. It takes 4 bits of storage for each pixel to make 16 colors. 
4 Bits is half of a Byte ( 8 bits) so 640 X 480 X 1/2 Byte = 153,600 Bytes, or 154K of Video Memory. The low end VGA card is 256K, so you are in good shape. 
To move up to 256 colors, each color takes 
one byte, so 640 X 480 X 1 Byte makes 307,200 Bytes or 307K or a 512K Video Card to run that resolution. Here's a chart 
to help you decide how much Video Memory you want to start with.
Current Catalog Prices are:
256K    $29
512K    $39
1 Meg   $63
VESA Local Bus - $95
VESA Local Bus with Accelerator - $129
VESA Local Bus with Accelerator and 2Meg - $208
Go 1 Meg at least with a color monitor.
A Word on VGA 
VGA cards are crashing in price. Couple that with the fact that you can get a "paper white" VGA Monitor (black and white) for $89. Hmmmm...check it out at the 
Show before you go Mono. May be irresistible.
The PC HELP pick: The Monochrome VGA Monitor for starters.
Installation:
Plug the Monitor AC cord into an outlet, or some plug directly into the Power Supply of the Computer from the back of the 
Machine.  Plug the Monitor Cable into the Video Board (next).
 Mini Glossary #2
VIDEO
VIDEO MEMORY  - RAM on the Video Card itself to increase how many colors, pixels and size graphic your monitor 
can display. Takes the burden off of the CPU, which thinks graphics is a pain in the ass. It likes to do numbers and text. In fact, to the CPU, even converting 
numbers to text is a barf . A 512K card has 1/2 Megabyte of Memory onboard. 800 x 600 
x 256 that is, 800 pixels wide x 600 pixels high by 256 colors is possible (barely) with a 512K Card. Watch it! There is regular old DRAM, on most cards, 
and VRAM, special video memory. If you are paying for VRAM, make sure you get it. 
Got it?
VIDEO ACCELERATORS
A new crop of Cards that speed up screen redraws especially in a GUI (Graphic User Interface) like Windows.
LOCAL BUS
A direct connection for your Video that makes Graphics happen faster. You will quickly learn that you spend most of your computing time waiting for 1) 
The screen to redraw and 2) The hard disk to stop cranking. You minimize this by 1) speeding up your Video and 2) keeping your hard disk unfragmented 
and cached. Read up on it. I can't explain everything 
for you. I got to make a living too. A Local Bus card sends and fetches instructions directly to the CPU, bypassing the bus that everything else in your system is 
jockeying for position on. If you are downloading a dirty GIF in Windows over your modem, and it is displaying while downloading, everything in the system 
is fighting for CPU time. If the Monitor takes the CPU over using the regular 8 bit bus line, nothing much else is going to happen.
PIXELS - The more dots you have on the screen, the more colors and more realistic the picture. Watch the first and last numbers of three number specs. 640 X 
xxx X 16 is pretty normal VGA. The 16 is the number of colors. 16 is ok, you can't view color photos with less. Many programs, notably Windows, won't 
show photos with less than 256 color capability. 800 
X xxx X yyy is considered Super VGA. 800 X 600 X 256 is what I run with a Tseng 1 Meg Video Board and a NEC 
Multisync 2A Monitor I picked up refurbished.
The Monitor (video) Board
For whatever monitor you buy, you have to plug a board into the computer to run it.  A used Mono board can be had for $20 everywhere.  All those boards 
that came out of old PC's and XT's and all the Manufacturer over-runs are sitting around waiting for you.  So you can have up and running video for $89 or 
so.
MONO (non-VGA)
Look for: A Hercules compatible card.  This board `interprets' graphics.  With a simple program such as SIMCGA available on bulletin boards or from clubs, 
will run most CGA Graphics programs. A bit of a pain. Also look for a parallel or serial port built in. Saves another $10-60. Hercules is interesting; a 
program written for Hercules has graphics better than CGA, EGA and many VGA versions. The graphics are tight and crisp. Centerfold Squares (Artworks, 
Inc. My favorite sexist 
software) looks better in herc than in Super VGA! But finding herc programs is getting harder all the time, and you are still talking black and white.
COLOR (and Mono VGA) 
CGA, EGA and VGA cards plug in the same way.  May need software (provided) to run, and EGA and VGA may have 
memory slots. Some VGA cards are downward compatible; that is, you can run Mono, CGA, EGA or VGA with them.  
CGA and EGA are dead and buried. If your local dealer offers you an EGA monitor system, tell him his checkered suit 
looks nice with the polka dot tie and get out of there quick! 
There is no need to buy an 8 bit VGA card if you are building an XT. Simply place a piece of electrical tape over the second connector, and use the 16 bit card as 
an 8 bit until you get a 386/486 Motherboard. It won't be long. There may be 16 bit VGA cards that don't work this way, but I haven't found one. 
VGA cards are rated by memory. 256K is certainly adequate for a starter. but you can't use higher resolution states like 800 X  600 X 16. 
Installation: 
Plug the board into an expansion slot, usually the farthest left.  Plug the Monitor cable into the small receptacle on the back of the card. Use care here. Trying to plug 
in a VGA Analog connector into the board blind is the leading cause of Monitor trouble: it fits just enough to push a pin or two back up into the plug. If you are 
having trouble with your monitor, inspect the connector VERY carefully. Gently pull any pushed in pins back out (With the Monitor OFF), taking care not to deform 
the pin. Some old Mono Monitors get their power from a plug that goes directly to the Power Supply. 
Frequencies - Different Monitor resolutions operate at different frequencies. Better VGA cards will have a dipswitch bank 
on the edge of the card, accessible from the outside, or will auto-select. If you get scribbly lines on your Monitor when you boot up, you have the wrong frequency 
selected.
The Memory  
THE place you will have to do some digging.  Think of Memory as a commodity- the price fluctuates day to day, and when 
you ask for a price, the dealer will likely pick up the phone and call some Chip broker for the latest quote.  Seriously!  This is due to 1988's chip shortage, 1992's 
Korean Tariff and 1993's factory burn out in Singapore. This is a global economy, folks Prices have come way down, but, like gold, some dealers kept the highest 
price.  PLEASE buy from a Catalog or a 
Show.  Compare prices.  Be patient. A national software chain sells 256K chips for $19.99. Pay $1 at a show.
Mini-Glossary #3
Memory and Speed
MEGAHERTZ - The speed rating of the CPU. An XT was 4.77MHz. An AT was 10 MHz. A good 386 board is 33Mhz. 
Higher is better. Combines with other parts of the system to determine overall speed. HIGHER IS BETTER.
NANOSECONDS - Memory Chips are rated in Nanoseconds, an infinitesimal measure of time. 60 Nanosecond chips are faster and more expensive 
than 70. Two years ago, 120 Nanoseconds was about standard. The range now is usually 60-7080. LOWER IS BETTER.
DRAM, SRAM - Dynamic Random Access Memory is what all clones except old COMPACs use to make up the Memory 
in your machine, measured in Megs. Don't confuse this with Megabytes of Hard Drive Storage. Individual DRAM chips are going out of style. Your new 
Motherboard probably uses SIMMS, which put 9 chips on a single board to make 1 Meg of Memory (a 1 X 9) that takes less space and is infinitely easier to 
install. Why 9 1Meg Chips to make 1 Meg of Memory? 8 1 Meg lines to the CPU plus 1 for parity checking equals 1 eight part Memory bank. 1 X 3 
DRAMS are confusing. Suffice to say that it is 9 1 Meg Chips, stuffed into a three chip package. There are 4 x 9 SIMMS, which puts 4 Meg on each SIMM. 
The more Memory you stuff on a SIMM, the more Memory will fit on your Motherboard. Older SIMMS and DRAMS came 
in 64K and 256K sizes. Buy no smaller than 1 Meg increments. Why? A 256K DRAM or SIMM is as useless as last week's Lotto Ticket  when replaced, 
which you will want to do almost immediately. You just throw them away or stuff them in the drawer with your mood ring. SRAM is used in CACHING, a 
scheme employed by better Motherboards to speed up the 
machine. HIGHER IS BETTER.
WAIT STATES - If the CPU runs faster than the Memory Chips, the CPU must go into a WAIT STATE and twiddle it's 
thumbs while the Memory Chips finish what they are doing. If your machine locks up on boot, one thing you can try is changing the WAIT STATE 
in Set-Up from 0 WAIT STATE to 1 WAIT STATE. Here's a cool  little formula to determine the WAIT STATE of your finished system: 1 
DIVIDED by the MHz of your CPU TIMES the number of banks on the Motherboard TIMES 1000 tells you the Nanosecond Speed of the RAM 
necessary to run at 0 Wait State. For Example: a 386-33Mhz CPU on a Motherboard with Bank 0 and 1 filled. What Nanosecond RAM Chips do I 
need to run at 0 Wait State?
	or 60 Nanosecond Chips to run 0 Wait State.
LOWER IS BETTER
RAM - Random Access Memory. If you have 4 Meg of Memory, you have 4 Megabytes of Random Access Memory. Don't 
fool yourself into trying to run Windows Enhanced with less than 4 Meg. You'll spend all day watching the hard drive thrash. HIGHER IS BETTER.
ROM - Read Only Memory - Stuff that gets remembered when the power is turned off. Don't worry about it. It's there.
DRAM Chips come in 64K, 256K and 1 Meg sizes, plus "banks" of chips in new motherboards called SIPPS and SIMMS. 
You will probably use SIMMS which make your life a whole lot easier. Installing chips guarantees that at least one of the eighteen you are putting in will have a 
leg sticking out of the socket. The entire bank of eighteen will refuse to work until you find that leg that is sticking out. It WILL happen. Putting in a SIMM is a 
breeze. Can be done in seconds. Current show price is about $36 for a one meg SIMM Your Motherboard must be set up for SIMMS in order for you to use them. 
Your Motherboard came populated (with chips) or at 0K (most likely).  There will be a bank of 4, 6 or 8 rows of empty chip sockets.  A Memory chip looks like a 
small after dinner mint with teeth.  Your Motherboard documentation (however little 
they provide) will tell you that it takes one or more of these size chips.  Use the highest you can.  It takes 9 256K chips to make 256k of memory (or 9 1 Meg ships 
to make 1 Meg). The ninth chip is for parity checking and other good stuff.
Motherboards require you to fill two rows or one full bank of sockets with chips to work, or one SIMM bank.  You will have to use 18 256K chips to make 512K of 
Memory.  If you can use 1 meg chips, fill the same two banks with 18 chips and you 
have 2056K of Memory!...and you still have empty rows you can fill later.  1 Meg is the way to go if you have to use DRAM Chips.  Buy from a Computer 
Show or a Catalog.  If you call a dealer, he probably bought from a catalog, and will add lots of dollars to that price.  Pay $1-2 each for 256K, pay $3 to $4 
for 1 Meg. Some dealers sell "Pulls", i.e. chips they have pulled from other machines. You make this call: you are taking a chance. Don't pay more than half 
of a new chip's cost.  Pay $36 or so per 1 Meg SIMM. As far as I can tell, 3 chip SIMMS are as good as 9 Chip SIMMS. Please write to me if you know 
different.
SPEED-Chips vary in speed.  The LOWER the number, the faster the chip. Usual values are 60, 70, and 80 Nanoseconds, 
with 100 Nanoseconds and 120 Nanoseconds going out.  Believe it or not, many vendors charge the same price, what ever the speed.  You can usually 
have one bank of 80 and one bank of 100 or 120, but cant mix them in the same row. Lower number chips may be TOO fast for your machine. That is 
why new boards are 0/1 wait state switchable. If the chips are running too fast, you switch back to 1, a longer wait state. Read up on it.
How much Memory?  Anything less than 4 Meg is impractical if you are even going to run a good game or a spreadsheet.  640K- 1 Meg is the most 
"conventional" Memory DOS can address, and anything above that is used best as XMS Memory under Windows (each program is loaded so that DOS 
is fooled into thinking that the program has it's own 640K), for a RAM Disk (making your computer pretend it has an extra disk drive), Print Spoolers 
(sends printing jobs ahead and reducing your wait), disk caching and new stuff every day. DOS 5.0 makes good use of higher memory. Windows 3.1 
uses as much memory as you can throw at it, and uses it well.  1024K is usually ok to start on a low end machine without 
Windows, makes 640K Conventional and 384K extended (not Expanded) Memory available, but with 1 meg chips, you 
have to fill 2 banks, so you get 640K Conventional Memory and the rest Extended Memory.  As more programs add uses for so called above board 
Memory, there will be more uses for it. Expanded Memory (also called LIM for Lotus, Intel, Microsoft, the consortium that approved it) used to be more 
useful, "paging" in and out in 64K chunks to imitate regular Memory, usable in Lotus 123, CADD programs and not much else. Your Motherboard 
documentation will tell you whether 
you have Extended or Expanded Memory on board. Some motherboards say "expanded" and it really is extended. If it is expanded, it comes with a 
driver to page in and out in 64k chunks. It uses the same chips. A few of the added Memory boards use Static RAM chips. Some static RAM chips cost 
$40 APIECE, and you can't get them even if you have the bucks. Read before you buy. Extended Memory is now handled via a software device driver 
called an XMS specification. 99% of all new Software is written with XMS in mind. The program turns over control of Memory to the XMS Manager, 
who wither negotiates with DOS or does an end around to avoid DOS. The upshot is, the Driver sweats keeping the program running and not you. DOS 
5 comes with EMM386, which handles both Expanded (\ram) and Extended (\noems) 
emulations. XMS only works full function in 386SX and up. Windows, being the hog that it is, uses a Hard Disk Swap File to further keep you running 
without out of error messages. Keep at least 2 Meg available on a Hard Drive for Windows Swap File to use.
If you have never installed chips before, take apart something old, like a radio or answering machine that no longer works (every house in America has a broken 
answering machine, I think).  Make sure it is unplugged (of course) and find an IC 
chip (described above) (one that's in a socket, not soldered in) and insert a small screwdriver under the chip as far as it will go without force. Pull up gently. Stop. Slip 
the screwdriver a little further in. Pull up gently. Stop. Insert the screwdriver under the other end. Pull up gently. That should do it. If you can't pull it out, there are 
IC extractors available very cheap (and very expensive. I had to buy a $60 one for special job) at electronics stores. Repeat until the chip comes out. Removing chips is 
a developed art. I still break them, and the genius manufacturers couldn't be bothered to key the chips to only go in one way. Put it back in. Repeat this a number of 
times.   
Go ahead and, with help if needed, install the chips and set the Motherboard. When you go to install DRAM chips, they are usually put in with the notch facing the 
power supply.  You usually have to bend the pins on new chips SLIGHTLY inward. 
Use something with a flat edge like a plastic ruler and bend them gently, gently all at once. Make sure they go in straight and all pins go in. The notch on the chip 
is usually matched to a notch on the socket. Get help here if unsure!!! Install the 
first chip in a socket that is easy to define, and the others will line up. Inspect each chip with a flashlight when the chip is in but not pushed down all the way. Make sure 
that all pins are inside the sockets, or start over. When you are comfortable, 
push down firmly, but not hard enough to bend the Motherboard. Touch something Metal before handling the chips.  Static electricity can make them 
instant idiots, erasing everything they learned at the factory. The sockets may be designed to accept both 256K and 1 Meg chips. COUNT THE PINS and 
match up the number of pins on the chips and in the socket. It 
is incredibly easy to put the chip in the wrong size socket. There may be a dipswitch on the Motherboard that you will set to tell it how much Memory you are 
installing, and what kind of monitor you have. The documentation will explain the 
switch.
Remember, 9 chips in a row for every unit value of Memory (and I said no Math..oh well).  9 256K chips makes 256K of Memory. 
SIMMS:
Carefully snap the SIMM into place, making sure it is well seated before you click it into place. If the memory refuses to count off, remove and re-seat each 
SIMM.
Floppy Disks , Hard Drives, CD's n' such (I/O devices) 
Before you can load a program or save a file, you need to put it someplace semi-permanent.  This is because when you exit a program or turn the computer off, 
everything disappears!  Lost forever.  Gone. Quicker than Ross Perot. You need a device 
or devices to save to a floppy or hard disk. You aren't going to get away with just one size floppy drive. The world is against you. Get both - get a 3 1/2 High 
Density and a 5 1/4. You may very well be able to get away with a low density 5 1/4 drive. High Density 5 1/4's are notoriously bad disks. Make the 3 1/2 the "A" 
drive.
NOTE: If you ever have to call the B drive A for a program, go to a DOS disk or sub directory and type ASSIGN a=b,b=a. 
That will temporarily reverse the drive assignments. To get back, go back to DOS and type ASSIGN by itself.
Installation.  You need a board.  Read the rest of this article before deciding. 
You need a hard/floppy or floppy controller.  You need it to be MFM, RLL, SCSI, IDE or ESDI if you buy a Hard Drive. 
Make sure the controller you buy is proper for your Hard Drive and make sure it is 16 bit if you are building a 286 or up.
The Controller
For floppy disks only: you can get a half-card floppy controller cheap. Plug it into an 8 bit slot near the power supply.  You need a cable to go from the controller to 
the back of the drive. The plug will be marked 1 on one end and 36 on the other.  1 usually goes on top. There should also be a different color wire on one end of the 
"strap" of wires. This color designates wire one. If the disk drive lights and doesn't go out when you fire up, you have it backwards.  The other end of the cable 
should have two card edge connectors, marked with numbers as described above.  There is also usually a slot in the female portion keeping you from putting it on 
backwards.  One card edge connector may have a twist in the cable near the 
connection.  This and the fact that it is the end of the cable indicates the Drive A connector.  Plug it into the back of the drive, which you have slid into the slot in 
the case.  Plug one plug from the power supply into the drive.  If you have bought a second drive, the other card edge connector hooks to that drive to make it drive 
B. You MUST follow the manual for the drive or call the Manufacturer to set the little jumpers on the drive near the back to get the drive configured correctly. To 
me, this is the most frustrating part of putting a system together. Most manufacturers use jumpers which are tiny black sockets that connect two pins together. They 
are near impossible to remove with or without tweezers, and sometimes you 
end up having to move these jumpers 10 times or more to get the configuration right. Hey manufacturers, use dipswitches! With a twisted floppy control cable, 
set both drives to the second position, which may be DS1 or DS2, depending on 
whether the manufacturer starts counting at 0 or 1. In any event, it's the second drive position.
For hard drives, you need a separate controller, or a Hard/Floppy drive combination controller. In most cases, you will be using the latter. Follow the 
documentation.
Interesting note: You can sometimes put a 8 bit hard drive controller in a 16 bit board. You can put a 16 bit VGA card in an 8 bit slot. But, wonder of wonders, 
you can't seem to put a 16 bit VGA Card in a 16 Bit slot with an 8 bit hard drive controller! It seems that the second 8 bits of the VGA card conflicts with the 
addresses used by the 8 bit hard drive controller. And you wanted to be a computer repairman! Figured this out after hours of agonizing over a failing system 
where all cards checked out OK individually.
Types of Floppy Drives
Besides the old standby 360K 5 1/4, there is a high density 5 1/4 that stores 1.2M of data.  This drive is problematical.  You will not be able to write to a low 
density diskette and use it on another computer with a low density drive without using the 
/4 switch when formatting.  There are also 3 1/2 inch drives.  The disks it uses are hard, less likely to go bad, and fit in your shirt pocket without a sleeve.  Wonderful. 
Old low density 3 1/2's stored 720k and quickly went out of fashion. High Density 1.44's are the standard Buy the high Density.  Pay $30 (used) to $65.  Installation 
note: I had my 3 1/2 high density drive set to Read Media, which meant that the drive decided which type of disk was in the drive.  A friend gave me a program on a 
high density diskette.  The machine wouldn't read it.  To make a long story short, she had formatted the high density diskette to low density, and the drive to trying 
to read high.  I changed the jumper to read the disk type from the machine instead of the Toshiba drive. Problem solved.  If your BIOS routine sets disk types in the 
Setup program, do it this way. 
There are some new drives out there. There are 2.88 Meg 3 1/2 drives. Why??? How dumb do they think we are? Are we 
supposed to buy this overpriced drive, pay for overpriced disks, and drool for 5.6 meg disks next year? Anything less than a 10 Meg disk is silly when it takes 1 
Meg to save a decent Drawing. AVOID this drive and wait for Floptical, comin' at ya in 1994. 20 Meg per disk. 
ANOTHER NOTE: This will pay for reading this article many times over. If your BIOS is set in the set up routine to read 
high density diskettes, and the drive is high density, setting the jumpers right on most models will let low density diskettes 
format to high density! There. I've just saved you $3 a diskette for the rest of your life. Send $10 to Greenpeace. Don't listen to the guys who tell you that 720K disks 
formatted to 1.44 aren't reliable. Hogwash.
Caution: Some computer manuals claim that you should never do this. They say that the low density disks are not made to 
be formatted high, and you will lose data. I have NEVER had this happen, so you make the call. If the only copy of your will is on a low density disk formatted to 
high, back it up somewhere. Personally, I could write my will on the label of a 3 1/2. With my newer IDE controller, the old jumper trick no longer works. Now I 
gotta drill little holes in the left hand side of low density disks. I still refuse to buy high density disks.
Hard Disks
Ok, ready for some jargon?  There are MFM drives (usually old) RLL, SCSI (pronounced Scuzzy for some warped reason), 
IDE and ESDI drives.  Buy whatever you get the best deal on, and fills your purposes (if you can afford ESCI, you probably aren't interested in building) but your 
controller MUST be compatible with that type. buy a 16 Bit controller card. You can get 40,80, 120, 1 Gigabyte and up Megabytes of memory.  Read up on it.  
40M is about the best compromise for the limitedincome builder.  Buy a compatible Hard/Floppy controller to match the drive and 8 bit for XT or 16 bit for AT) 
to control all the drives.  Buy a half height to save room for a second hard drive. Pay $1 to $2 per meg for a hard drive. A 250 Meg hard drive is close to the same 
price as an 80 Megger. Get a book on formatting. Get the shareware programs IAU and 
HDDIAG from a bulletin board or a Computer Show. Ready for a crap shoot? Show up at a show AT OPENING TIME. 
Someone will invariably be there selling hard drives pulled from old machines for 50 cents a megabyte. For fifteen dollars you can take home a 30M drive that has 
a 50-50 chance of working. Like I say, you make the call. I bought a 42MB voice 
coil (as opposed to stepper motor) drive for $40 years ago and it only needed re-formatting.  Then again, chances were just as good that this drive was used as an 
anchor for a crab pot for six months. Again, it's a crap shoot.
Hard drives come in full size (pass_), half size (both 5 1/4) and 3 1/2 size. There are now 1 inch drives and credit card sized drives. BE SURE that the case you buy 
will take a full size hard drive and two floppies before you buy a full size drive.
Older MFM/RLL Drives are also split into Stepper Motor and Voice Coil. Be aware the stepper motor are cheaper and will 
give you great service, but cannot be moved without "parking" the drive. A stepper motor hard drive is just like a turntable; if you shake the drive, the needle will go 
skittering across the surface of the drive platter, destroying data as it goes. Most 
hard drive repairs are reformatting as a result of the user banging the machine around, or, (GASP!) turning the machine over and shaking it to get out a loose 
screw. Voice Coils can be safely moved, and are more expensive. Ask the seller which the drive is.
There are new hard drives which store information on glass prisms. Great. I can just see me dropping one. I hope they make them out of jelly jars. They never 
break. Especially the ones with Pebbles and Bam-Bam on the side.
High Tech Hard Drives
SCSI works by putting the controller on the Hard Drive, and the floppies work off of that controller. IDE is an animal unto 
itself. IDE also puts the controller on the drive, and then plugs into a card (not a controller) that also has the parallel, serial, game port and floppy controller on the same 
card. The I/O ports are problematical. I takes me twenty or so tries to get 
everything right whenever I add or move an I/O device. An OK hard drive is rated at 28Ms. There are new cached IDE 
Controllers that cut the time, they say, to .3 Ms. The price is coming down, too. Expect to pay $29 for a regular IDE with I/O, and $179 for a new, lower 
priced cache controller.
RLL is dying. RLL was really MFM type technology but used Run Length Limited encoding to format the drive at 26 
sectors per track instead of 17. Increases the capacity of the hard drive by 50%. What doesn't work in most cases is formatting a MFM drive on an RLL 
controller. The drive works for two days then poops out. There seems to be no way to look at a used controller and tell if it is MFM or RLL. Make sure. 
Also be VERY wary of used controllers thrown in a box for $5 apiece. Most of these boards have been stripped of their chips, or have broken pins on the 
connectors.
Installation
MFM/RLL: There is a big cable that goes from the Hard Drive to the controller and a small one.  Match pin one to pin one all the way around.  IDE/SCSI: 
There is one connector that hooks from the drive to the interface board. The actual 
controller is built into the drive's logic board. Slide the Hard Drive into the case, connect these cables, and plug in the power supply lead. For two drives, get a 
book and follow the instructions. It's not that hard, but you have to deal with twisted cables and terminating resistors and such for MFM/RLL, and Master/Slave 
settings for IDE. The terminating resistor goes on the last physical device.  There may be a jumper on the board to hook up the light on the case so that it 
merrily blinks when your hard drive is working.
SCSI, IDE and ESDI use their own single connector cable. Beware of old motherboards that call themselves IDE. Citizen called their hard drive system IDE, 
but it used MFM drives and connectors. A call to their tech service confirmed this, and the guy on the other end was defensive and abusive- 
"So what's wrong with MFM?" 
"I just went out and bought a replacement IDE drive per your specs". 
"Well, go buy an MFM." 
"But MFM is more expensive in higher capacity drives. Just tell me how to disable the onboard controller." 
"Well, if you must, make sure that jumpers 16 and 20 are shorted." 
Naturally, it turned out 2 hours later that jumpers 16 and 20 must be OPEN. Most jumpers on that Motherboard are undocumented. 
The MFM/RLL hard drive must be set up in your BIOS program, then low-level formatted and high level formatted. Pick 
up a book at the library, borrow one or ask a friend. The procedure is not difficult. The two aforementioned share-ware programs IAU and HDDIAG makes the 
process easy and configures the drive to it's optimum performance. IDE drives 
NEVER get low level formatted. If you do, it goes stupid and becomes an MFM.
On clone 286, 386 and 486 machines, you must pick an entry from your Set-up program, which comes up when you start 
the computer. It is accessed by a particular keystroke, referenced on the screen before the machine actually boots DOS. The message will say something like 
"Press DELETE to enter Set-up". Set-up writes your component information into the 
CMOS. CMOS stands for something or other which I always forget. 
Shareware programs are available to help you pin down which "number" of a standard set of numbers your hard drive type is. An old IBM 10 meg drive is #1. 
An old Seagate 412 is #23. The BIOS will ask you for this number. If you bought from Crazy Johns Un-guaranteed Hard Disk Bargain Nearly New Shop, you 
may have to do some digging to find the number. 
Disk Manager, which comes with Seagate Hard Drives, will interrogate the drive for you, but is a real pain in the butt when the drive isn't Seagate. Here's a 
real kluge. My hard drive didn't fit my table, so I hooked the hard drive up to a machine 
with a settable drive table, formatted it, then saved the settings to the disk with Disk Manager. If the drive ever crashes, I'll probably have to repeat this process or 
update my BIOS. You need to know the number of cylinders and number of heads, at 
a minimum. The number of sectors for MFM is usually 17 sectors, RLL 26 or 27. Call the local computer club to track down a list of hard drive specs. 
You match the number of cylinders and number of heads in the drive table in your set-up 
program WITHOUT GOING OVER. Just like the Price is Right (hi Bert!). If your drive has 8 heads, you can pick 5,6,7 or 8, but not 9.
Skip this paragraph unless you end up with an IDE drive. I  learned, by force, how to set up one of these bears. The IDE drive table entry is determined by 
MULTIPLYING the number of heads x the number of sectors x the number of cylinders, and matching that to the drive table entry that most closely equals 
the number of heads x cylinders x sectors. Sheesh. The advantage is, you are not limited to the closest without going over rule. The one thing you MUST 
NOT DO is low level 
format an IDE drive!!! They are low level formatted at the factory. If you do a low level format, it becomes an MFM drive. This exciting information was 
passed on to be by the Seagate technical department AFTER I had low level formatted three times trying to get the bear to work. There was NOTHING in my 
documentation telling me not to do a low-level. I had to get another drive and start over to get the full performance from the drive.
SCSI involves setting the hard drive table to "not installed". The information on the drive is send to the BIOS at boot up time.
FORMATTING
Formatting the MFM/RLL hard disk is involved but not difficult. HDDIAG and AMIDIAG (AMI, the BIOS people) are 
both free or shareware programs available at Computer Shows and through magazines for a couple of bucks each (Registration will cost more. These folks 
deserve their money.)
They will walk you through the low level formatting, which prepares the disk for your system. Seagate and some other manufacturers come bundled with 
Disk Manager, which is a great utility, but only works well with that brand hard drive. Next you run your DOS program FDISK, in which you set up the 
DOS partition. If you are running DOS 3.3 or less (hardly anyone likes DOS 4.01) you are limited to 32 Megabytes per partition. Thus, a 40 Meg hard 
drive must be split up into more than one partition (C and D [and maybe E]). A drive runs faster if you minimize the C partition and maximize the 
others. The D and above partitions run much faster. No big deal to run FDISK. Finally, you high level format the disk, i.e. format C:/s which makes the hard 
disk ready for use and bootable and format d: which prepares the D drive. Take this whole process slow and easy. Block out quiet time to do it.
Other I/O... the M word.
CD's 
Yes, this is the same type of CD that you put on to listen to yer basic Achy Breaky Heart or Beethoven's Fugue for Fuguettes or whatever it is you ken to, and 
Laser Disks for Video are the same breed of animal. This Christmas, Phillips VIA Magnavox VIA whatever they call themselves this year are touting interactive 
CD video, which in strict Computerese might be designated Organized Thrashing.
In any event, you can put a whole mess of information in a very small space on a CD. The music on  the disk is actually only taking up a very small portion of 
available space, and, whether out of guilt or whatever, the manufacturer puts the information on a couple of times for good measure. Hence over sampling, hence 
32X over sampling. You can't hear any difference over 4X over sampling. Hence Mr. Sony lives very, very well, Domo Arigato, on the extra money you paid 
for those other 28 samples. Anyways (are you still awake?) there is usually some Video information on the Disk as well  that you just can't get to because the 
video output stuff was bypassed in the manufacture to pay to put in those extra 28 over samplings. Now we're getting somewhere....
You see, if they let you have everything you could use the CD for the first time you bought a CD device, you wouldn't buy any more CD equipment. I have a 
perfectly good portable CD player right next to my computer. Why can't I use it as a CDRom for my machine? It frosts my butt that I can't.
Ok, if you want it, you will pay $149 and up for a CD-Rom. You also need an interface card. If you want the system to work 
at it's maximum potential, you will have a SCSI interface that also ties in your sound board, your Hard Drive, Floppies and I/O ports. Don't get me started.
The problem with the $149 wonder is that it is sssslllllloooowwwww. You will pay $199 to $800 for a decent CD-Rom. The difference probably costs the 
Manufacturer at least $5. The CD ROM will provide you with a READ ONLY device that 
allows you to look up your drunk uncle in Seattle for the mere cost of the $49 CD Telephone Directory for the West Coast. Let's just hope you call him before 
he moves... and changes his phone number (he owes mucho alimony). If he does, you need a new Directory. What are we going to do with all these outdated 
CD's 5 years from now?
CD Rom Speed
CD Rom devices have to move at a certain speed, or the sound won't be able to be in real time with the pictures. Anything animated would look like a bad 
Japanese movie. So the industry came up with "MPC Compliance". All newer CD Rom 
drives are MPC Compliant, even the Mitsumi (no technical support because they don't put their addresses on anything) Company . Panasonic came out 
with a double speed drive a few years ago, and now everyone is jumping on the bandwagon, including Mitsumi (I still can't find their address) 
Company.
CD Rom Installation
You should absolutely, positively without fail operate your new computer system for two weeks BEFORE installing a CD 
ROM, Sound Board, Scanner or anything else. Make damn sure your Modem, Windows Video Drivers, mouse, etc. are 
working under all conditions before attempting to install one of the above devices. There is an absolute ART to getting all devices to work on their own IRQ's, 
Memory addresses and DMA channels. If you don't know whether your modem 
operated correctly before you installed the CD Rom, you can't narrow down the cause of your woes.
An internal CD Rom has three main connections: a power socket that you hook a lead from the power supply to, a small two pin cable and a IDE type connector 
that both hook up either to a CD ROM card or, if you live right and buy the right equipment (I never do either, it seems) both hook up to your sound card. 
Once those connections are made you will need to add device drivers to CONFIG.SYS and AUTOEXEC.BAT in your startup files.
I would suggest that if you are hooking up both a CD Rom and sound card, you install the CD Rom first without the sound card in the machine. There is no way 
to properly debug a memory problem until you know that all but one device is operating.
A disk will come with the CD Rom to install the startup device drivers. You need to know what IRQ's are available so that you can tell the startup program 
which IRQ to use.
Your best bets are IRQ 10, 11 and 12. If Windows is on your machine, type MSD from the Windows sub-directory and 
choose IRQ usage for a current state of what is ACTIVELY using IRQ's. It's not foolproof, but it helps. You will probably need to choose a memory address. 
This is a trial and error process. This is what I would suggest:
Accept all the defaults the start-up program suggests. Load device drivers in CONFIG.SYS and AUTOEXEC.BAT low. 
Choose NO DMA, and make sure you have BUFFERS=20 or higher and FILES=40 or higher. I don't care what Microsoft 
says, just do it. Set buffers for the CD Rom ridiculously high, say 50. You can lower it later. Test the CD under DOS. Start Windows, install the driver for 
MultiMedia and test the CD Rom under Windows. If all goes well, go back and try DMA channels 1,2, etc. until you get one that works. Then start lowering the 
CD Rom buffers by 5 and re-booting until the drive refuses to load. On mine, it's about 35 (which is 35,000 bytes of precious memory, folks!). Then, and only 
then, load MSCDEX high in AUTOEXEC.BAT. Test. If successful, load the CONFIG.SYS driver high and re-test. Get away with as 
much as you can and then WRITE DOWN the settings someplace. Now, and only now are you ready to put in a sound card.
Here is the scenario for a working combination of MITSUMI CD Rom and Soundblaster PRO Sound card, a very common combination.
The CD Rom will not work directly with the sound card. Do not plug the cable into the Soundblaster card, but into the CD Rom card. Plug the two wire 
audio lead onto the Soundblaster card. Load the CONFIG.SYS driver high with 35 buffers. Load MSCDEX high in AUTOEXEC.BAT. You are going to 
have to choose a high memory range for the CD Rom, 
because the default WILL NOT WORK with the Soundblaster default. You should change the default CD Rom address and 
NOT the default Soundblaster address, because many programs ASSUME the Soundblaster is set to 220h. The reason you must choose a high memory 
address for the CD Rom is that Soundblaster uses some higher memory addresses in addition to 220h, and you MUST get above address 300h for the CD 
Rom not to interfere with the Soundblaster. Once again, the fruits of my hours of agony are passed on to you. You don't care.
A word about WORMS.
Write-Once-Read-Many. A decent idea. You never change the program contents of a Commercial Software package 
between Upgrades anyway (quick time out for a definition: SOFTWARE UPGRADE: Whenever enough people yell about a number of major 
bugs in a piece of $600 Software, the Company has some programmers fix the bugs, then they charge 
YOU $49 to $129 to get the bug fixes. This is America.), so this device would make sense. About the only time you will see one of these is if you go to certain 
software shops and appliance dealers (no kidding!) that sell you an empty box which you take to a machine on which is made a copy of the program before your 
very eyes, using the aforesaid  WORM drive. I think the WORM comes in because they get UPGRADES (see above) over the Modem. I did this once. In 
Delaware. The guy who 
made the copy was pissed off because he had a Chinese couple over by the Washers and Dryers and they were ready-to-buy, 
as they say. So this guy is watching Mr. and Mrs. Chen with one eye and trying to operate a WORM drive with the other. 
He was sweating all over the disks. After 3 attempts, he handed me a disk which, of course, when I got it home, did not work. I hope he got his 5% from our 
friends from foreign lands. A WORM drive would allow your Company to distribute Annual reports n such on a media that isn't alterable.
Sound Boards
Now,  you too can hear annoying {BEEP}s in 16 track Stereo Splendor! Only $189. This is an idea who time has come and 
the technology hasn't. These things have been on the Market for years, but are still plagued with problems. My dear Brother is sweating over his second board 
as we speak, trying to get the IRQ to agree with the WIN.INI settings to agree with the DMA channel to work under Windows. A board should plug in and 
work. What if you bought a car and the salesman said 
"This is a great little spitster, but, uh, by the way, don't change the radio station when you are making a right turn. If you do .....KABOOM!...."
Well, I gotta admit that I broke down and bought on of these things. Bought it over the Internet used. A Soundblaster PRO. 
It is a pain in the ass, but fun I guess, once I got (almost) everything working together. How do you casual users out there do it? I do this stuff full time and it drives 
me crazy. 
Live Video
Yes, dear friends, you too can capture the rapture of a Veg O-Matic Commercial and drag the Video into your Computer 
Monitor. But Wait! That's not all! You can even record it and play it back if you have 80 Megabytes of free Hard Disk Space lying around (who doesn't?) 
This is one of those areas where I get the tingly feeling that with a VCR tuner and a RGB converter, I can build one of these puppies myself. Stay tuned. Just 
like Ronnie Reagan and Star Wars, if I figure it out, I'll pass on the technology.
Put it all together and whattaya got? MULTIMEDIA!!! (Fireworks, patriotic songs, please...) They will put 
it all together for ya for $600 and up. As for yer humble servant DJ, I gotta do it piece by piece. CD Rom prices have crashed to $159, and some wonder boy 
is going to put a high speed Video Card on the Market for $99, and SOMEBODY in 
this blessed land of ours should come out with a sound card that works. For $79. You gotta have patience in this business, but know when to hold your nose 
and JUMP. Like the day not long ago  1X9's went down to $23. I sold my son at auction and bought 4 Meg (he was happy for me. "great deal, Dad!") Three 
days later Bush (an anachronism by the time you read 
this) slapped a tariff on the Koreans which drove the price up to $38. Then the plant burned down in Singapore. It affected 5% of DRAM production, but 
everybody raised their prices to $46 on that excuse. So you gotta be ready to jump.
PLUG N PLAY for 94
This is THE most overdue technological advance in the Industry. This shoulda happened in 1989. At the latest. According to all the magazines, Microsoft n' all 
those guys have agreed to a common Plug N Play standard for new hardware. Here's how it works. You get a new modem, you plug it in. It works. WOW!!!!!!
No longer will the machine ask ME which IRQ, DMA, COM Port, Parallel Port or Memory Address is available. How the 
hell should I know??? I gotta do two hours worth of digging in a diagnostic program or three to find out to a reasonable doubt what the machine knew all along! 
Don't ask me which hand the quarter is in when you are going to keep the quarter! 
Finally, the machine is going to keep track of what it is using, and will dynamically allocate IRQ's and such as it should.
Watch for Plug N Play in early '94. I predict it will be bigger than VESA Local Bus and will be accepted immediately (definition of IMMEDIATELY: sooner 
than total market penetration of OS/2). I'll be buying a Plug N Play Motherboard as soon as one comes out at a reasonable price and will include a section in 
Build Yer Own Version 4.
SUMMARY
You have installed the Motherboard and Power Supply, hooked up the speaker and LED's, inserted the Memory chips, set 
the Motherboard dipswtich(es), put in the Monitor Card and plugged in the Monitor, plugged in the keyboard, inserted the Hard/Floppy Controller, slid in and 
connected the drive(s), and plugged the whole shebang into the wall. You have left the I/O card and any optional devices such as mice and printers out of the 
picture until the basic machine is working well. 
Now turn it on. 
DON'T PANIC Tip of the Decade - If everything is hooked up right, you turn on the machine when you finish building and NOTHING happens, there are 
three usual causes:
1) The wrong frequency is selected on the video card. Turn the machine off, make note of the current switch positions, and flip a switch or two. If you get 
scribbly lines when you turn on, you have found the problem. Find the right switch combination, and you are in business.  
2)The Power Supply is not hooked correctly to the Motherboard. This is a really stupidly designed connection that bust fingers and tempers. Check it.
3)Memory - This is 70% of no starts. If you are using DRAM chips, one leg has squirted out of the socket. Trust me. I've done it ten times. Get a flashlight 
and magnifying glass and happy hunting. With SIMMS, a SIMM didn't seat quite right. Unsnap it and snap it back in. It may take three unsnaps and snaps to 
get it right, but it is VERY VERY common for this to happen. Remember this: EVERY chip must be PERFECTLY in place for ANY to work.
If everything is hooked correctly, the Memory will count off as it is checked, and you will be sent (hopefully) to a set up program in BIOS to describe and save 
the configuration of your system.  You now need to add MS-DOS from a disk to 
"Boot" the computer, and you are up. You need an operating system to run the computer. DOS 3.3 is the old favorite quickly fading in favor of  DOS 
5.0, a quantum leap. Avoid MS-DOS 4.x. Obtain the software disks for your operating system before you finish the machine. Have a bootable floppy 
nearby at ALL times. Mine is velcro'd to my Monitor. The moment you see your first A> prompt you are in business.  Open a bottle of champagne, 
pour one for me, and accept my hearty congratulations.

MY ORIGINAL SYSTEM
Piece
New or Used
Source
11/89
Current
Case- Baby AT
New 
Catalog 
$25.00
$25.00
Motherboard-AT286 
Amptron
New 
Friendly 
Rep
$199.00
$39.00
Monitor-Leading Edge
New
Gen. 
Comp.
$69.00  
$69.00
Mono Card w/ parallel 
port
Used
Friendly 
Rep
$20.00
$10.00
Power Supply 200 Watt
New
Disc. Store
$69.00
$40.00
Teac 5 1/2 Drive
Used
Show
$40.00
$ 5.00
Toshiba 3 1/2 HD Drive
New
Disc. Store
$89.00
$50.00
IBM MFM 10 Meg Hard 
Drive
Used
Show
$20.00
$10.00
Adaptec Hard/Floppy 
Controller
Used
Friendly 
Rep
$69.00
$15.00
Memory- 18 1M 80NS 
Chips
New
Show
$162.00
 $72.00
Serial Port
Used
Show
$10.00
$10.00
Modem 1200 bps 
(optional)
Used
Show
$20.00
$ 5.00
Switch and headphone 
jack (opt) New 
Radio Shack
$4.00
$4.00
======
======
TOTAL Retail $1995.00
$796.00
$354.00
THE COMPUTER SHOW SHOPPING GUIDE       DJ Elliott 
PART				                 Price1     Price 2     Price 3    Price 4  Price 5
=========================================================
=============
THE NECESSARIES
=========================================================
=============
CASE		  XT	               ______   ______   ______   ______   ______
			AT                     ______   ______   ______   ______   ______ BABY AT
		             ______   ______   ______   ______   ______
		TOWER	                ______   ______   ______   ______   ______
MOTHERBOARD 
			8088                      ______   ______   ______   ______   ______
								80286										 ______   ______   ______   ______   ______
							386SX											______		______		______
	______	______
							386DX											______		______		______
	______	______
						486SX												______		______		______
	______	______
						486DX												______		______		______
	______	______
					486DX2											______	______	______   ______   ______
POWER SUP       ____WATT				 ______   ______   ______   ______   ______
FLOPPY DR.     5 1/4 LOW						______   ______   ______   ______   ______
														5 1/4 HI				   ______   ______   ______   ______   
______
												3 1/2 LOW					______		______		______
	______	______
												3 1/2 HIGH			  ______   ______   ______   ______   ______
HARD DRIVE      ___ MEG		______		 ______	______	______	______
																	___ MEG   ______   ______   ______   ______   ______
																	___ MEG   ______   ______   ______   ______   ______
DRIVE			  HD/FL COMBO									______		______   ______   ______   ______
CONTROLLER  MFM 8/16 BIT				  ______	______	______	______	______
										RLL 8/16 BIT						 ______   ______   ______   ______   ______
						OTHER 8/16 BIT					______	______	______   ______   ______
															CABLES					  ______   ______   ______   ______   ______
									FLOPPY 8/16 BIT		  ______   ______   ______   ______   ______
																		CABLE						______		______	______
	______   ______
MONITOR														MONO	______	______	______	______   ______
																			CGA					______		______	______
	______   ______
																				EGA				______		______	______
	______   ______
																				VGA				______		______	______
	______   ______
															VGA MONO		  ______   ______   ______   ______   ______
		MULTISCAN, MULTISYNC			______   ______   ______   ______   ______
MONITOR								HERC MONO		 ______	______	______	______	______
CONTROLLER												CGA		    ______   ______   ______   ______   ______
													EGA 8/16 BIT					______	______	______   
______   ______
													VGA 8/16 BIT					______	______	______   
______   ______
	MEMORY								256K CHIP	______	______	______	______   ______
																1 MEG CHIP				______	______	______   ______   
______
											SIPP/SIMM						______	______	______   ______   
______
I/O BOARD																						______	______	______   
______   ______
 KEYBOARD																			______   ______   ______   ______   ______
=======================================================
==============
THE GOODIES
=======================================================
==============
MODEM		 
			_____BPS		INTE									  ______   ______   ______   ______   ______
			_____BPS		EXTE									 ______		______		______		______	______
			_____BPS		INTE									  ______   ______   ______   ______   ______
			_____BPS		EXTE									 ______		______		______		______	______
MOUSE								 BUS							  ______   ______   ______   ______   ______
												SERIAL				 ______   ______   ______   ______   
______
PRINTER			  DAISY WHEEL							______   ______   ______   ______   ______
			DOT MATRIX 9P										______	______	______	______   ______
			DOT MATRIX 24										______	______	______	______   ______
				LASER												 ______   ______   ______   ______   
______
				CABLE												 ______   ______   ______   ______   
______
FAX BOARD																	   ______   ______   ______   ______   ______
SCANNER																				_____	______	______
	______   ______

BLANK DISKS______________       ______	______   ______   ______   
______
SOFTWARE   ______________       ______	______   ______   ______   
______
SOFTWARE   ______________       ______	______   ______   ______   
______
SOFTWARE   ______________       ______	______   ______   ______   
______
SOFTWARE   ______________       ______	______   ______   ______   
______
SOFTWARE   ______________       ______	______   ______   ______   
______
OTHER            ______________     ______   ______   ______   ______   ______ STUFF             
______________     ______   ______   ______   ______   ______
Get a receipt. Get a phone number and address. Get a guarantee.
SECTION III - DOS Operating Systems and Startup Files
First of all, if you haven't already done so, upgrade to MS-DOS (not IBMDOS) version 5 or above. 
Anything less is just plain silly.
Operating Systems
You have learned about the Hardware. When your machine is finshed building and you throw the power switch, the CPU 
looks to the BIOS for instructions. The BIOS tells the CPU about all the installed peripherals, like hard and floppy drives, monitor, modem, printer, etc., then the 
BIOS goes looking for an Operating System. The Operating System on 90% of Intel Desktop Computers is MS-DOS or IBMDOS. Yes, you can boot up to other 
Operating Systems - CP/M, OS/2, UNIX, 
XENIX, etc. The vast, vast majority of software, though is MS-DOS/IBMDOS, and in my humble opinion, don't even worry 
about other Operating Systems. 
The BIOS looks to the boot record of the first active device it finds on Drive A or Drive C. The boot record is a special area at the start of a disk which, if not 
written over, contains the information the BIOS needs to boot up. In MS, the files are MSDOS.SYS and IO.SYS. If the DOS version is 5.0 or up, it also looks for 
DBLSPACE.BIN. DBLSPACE.BIN, if enabled 
and valid, tells the BIOS to split the Hard Drive into compressed and uncompressed partitions. Otherwise, IO.SYS and MSDOS.SYS tell the BIOS to look for 
CONFIG.SYS and AUTOEXEC.BAT in the root drive of the bootable device. These 
two files are files that you create or are created for you by others which tell the machine how and what to operate over and above the defaults. The defaults are 
pretty skimpy, and to operate in a decent computing environment, you will need to maintain decent CONFIG and AUTOEXEC files.
The 640K memory limitation is still with us, and if you have a 386 or 486 (or Pentium), you need to write good 
CONFIG.SYS and AUTOEXEC.BAT files to throw as much as possible above 640K. This is an art.
To cut to the skinny, here is a set of recommended startup files as a starter for MSDOS 5.0 and up.
CONFIG.SYS
FILES=40
BUFFERS=20
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386 NOEMS 2048 1024	<------only on 386/486 machines
DOS=HIGH,UMB <--------- only on 386/486 machines
DEVICEHIGH=C:\DOS\ANSI.SYS
FILES are set to 8 by default. This is not enough. Your program may not be smart enough to check for available file handles and may crash. Higher buffers make 
for faster operations during such activities as formatting disks and backing up.
Years ago at Microsoft, some nerd discovered that the area at the top of the first Meg had been forgotten by DOS. HIMEM opens this area up, called the A20 Line. 
It must be present to use higher memory functions.
EMM386 controls both upper memory (640-1024K) and high memory (1024-??????K). The NOEMS switch tells DOS to 
emulate extended memory, and RAM would tell DOS to emulate expanded memory (old and passe. You may need this to run older programs like 
old versions of Lotus and DataEase before 4.5. EMM386 and HIMEM must be loaded before you can use DOS=HIGH,UMB. 2048 tells DOS to 
use 2048K of high memory for XMS, the replacement for expanded and 
extended memory. The rest of high memory is left alone for other uses (RAMdisks, some programs). 1024 tells it how much memory to use when in 
Windows.
DOS=HIGH,UMB It does not matter where in CONFIG.SYS this line appears. CONFIG.SYS scans the whole file looking 
for this line before executing. DOS=HIGH tells DOS to load as much of itself as possible in upper memory, i.e. above 640K and out of your way. 
DOS=UMB tells DOS to scan the area between 640K and 1024K, and set up empty areas as Upper 
Memory Blocks where it can put device drivers, mice drivers and other TSR's.
DEVICEHIGH=ANSI.SYS tells DOS to load the extended character set (you will get to know ANSI graphics on bulletin 
boards) and the HIGH portion tells DOS to attempt to put the program in Upper Memory, above 640K. To intentionally NOT load the driver high, you 
would instead use DEVICE=C:\DOS\ANSI.SYS.
There are lots of other goodies to load through CONFIG.SYS like CDRom drivers and such. Remember that this is a one shot deal. You cannot load or 
unload (ok, I'm over-simplifying again.) device drivers once the machine boots up.
More Fun with EMM386
There are other switches that you use with EMM386 as you begin to tweak your machine. Most notably, when you begin to learn how to "read" upper 
memory, you may find that the BIOS has reserved an area of Memory that it really isn't using. You would tell DOS to attempt to load stuff in this are 
with an INCLUDE statement. You may also find that DOS is using 
an area of upper memory that the BIOS as failed to mark reserved but is using anyway. You would exclude this area with an EXCLUDE statement. Let's say that 
you know that b000-bfff is empty but reserved by BIOS for video, and that your 
network card is using d800-dfff but not informing DOS. Your EMM statement would change to the following:
DEVICE=C:\DOS\EMM386.EXE NOEMS 2048 1024 i=b000-bfff x=d800-dfff.
Notice that I am making implicit calls to the devices in the file? ALWAYS do this. Get in the habit. Always make calls to C:\DOS\ or whatever the path is. That 
way, if you make boot floppies or change your hard drive setup or whatever, you are never assuming DOS knows where to go.
Periodically search your hard drive for duplicates of DOS files and destroy old copies. Nothing can give you as much trouble as "Incorrect DOS Version" or 
using an outdated file like EMM386. Get a source for the new EMM386 and HIMEM files, 
etc as they come out. You can get them yourself by calling Microsoft Downloading Service at 1 206-936-6735. 'Smatteroffact, I'm online with 
them right now, downloading in the backround. MS-DOS version6.2 Upgrade was FREE from this service. 
AUTOEXEC.BAT
PROMPT $P$G
LOADHIGH C:\DOS\SMARTDRV.EXE 512 256
PATH C:;C:\DOS;C:\WINDOWS
TEMP=C:\WINDOWS\TEMP
PROMPT $p$g sets your on screen prompt to show more information than the default. Without this line, as you change 
directories on your hard drive, you would not see the directory you changed to, it would just always say C: Pretty dangerous during file deletes.
LOADHIGH tells DOS to try to load the following command into upper memory. Eliminate LOADHIGH from the line to 
load it low or if you have a 286. SMARTDRV.EXE holds the last few commands and results into memory so that if you 
make the same call over and over, the RAM will not have to fetch the same stuff over and over from the hard drive. With SMARTDRV loaded, type dir by 
itself from the root of C:. Type it again. You should see a decent speed difference. 512 is the amount of Memory in K to allocate from extended memory to 
SMARTDRV. 256 is the amount in K to use when under Windows.
PATH is a totally cool line which gives DOS a number of places to look before it comes back with "BAD COMMAND OR FILENAME". If you use one 
program a lot, like I use XTGOLD, add it to your path.
PATH C:;C:\DOS;C:\WINDOWS;C:\XTGOLD
Now you can type XTGOLD from ANY subdirectory on ANY drive, including networks and floppies, and it will find XTGOLD.COM and execute it.
It is a very good idea to set a TEMP variable in AUTOEXEC.BAT. Many programs create temporary files as they work, and if the TEMP variable is not 
set, they may attempt to store the temporary files in weird places, like on your CDRom, fer instance.
Although I could go on for a few u
hundred more pages about DOS and MEMORY, this thging has to end somewhere. Here's a few more DOS tips before I go.
Ascertaining the DOS Version
It is important to be certain which DOS Version you are operating; making Memory available with UMB's is futile if the user is running DOS 3.3. The 
Version of Microsoft Disk Operating System or IBM Disk Operating System running can by found at any DOS prompt by typing VER at the prompt.
C:\>VER
IBMDOS VERSION 5.0
Preparing to make adjustments to software: Backing up startup files
Before attempting to make changes to startup files, it is always a good idea to start by assuring that you can return the system to "where it was" before any changes 
are made. Make the appropriate backups of  Databases when prudent, and 
rename batch files before editing. Even if the Editor makes a backup when a file is changed, ( filename.bak), two edits of the same file wipes out the original file. 
Be consistant with file backup names to avoid confusion, especially if you may have to try different scenarios to solve a problem.
Before beginning file adjustments, make the following backups:
from the C:>prompt:
C:\>copy autoexec.bat autoexec.old
C:\>copy config.sys config.old
If you later need to restore the original file, from the C:> prompt,
C:\>rename autoexec.old autoexec.bat
C:\>rename config.old config.bat
Making a Bootable Floppy
The second step before making changes to critical files is to make sure the system can be accessed in the event that changes cause a "boot crash". An example 
would be where a user automatically runs Windows 3.1 from the autoexec.bat file, and MSCDEX.EXE is causing a crash in the boot sequence. The easiest 
recovery is to have on hand a "clean boot" floppy.
Place a new floppy into their A Drive and change to the DOS sub-directory of the boot up disk , usually C:, and type the following:
C:\DOS:>format a:/s
which places the DOS system on the floppy. If you are formatting a 5 1/4 low density (360K) floppy in a 5 1/4 high density (1.2 Meg) drive, have them add the 
/4 switch to the line, i.e.,
C:\DOS>format a: /4/s
MAKE CERTAIN the drive letter is correct! You can very easily (though not as easily as under DOS 3.0) format the hard drive! If the screen's message contains 
the warning "Are you sure?" , the system has determined that a fixed disk format is in progress. Answer N and begin again.
At the end of the format of the floppy, the system will tell the user that the system has been transferred, i.e. copied to the floppy disk.
Smart Computing Tip: Is is advisable for every DOS user to always have a bootable floppy close at hand. Being able to 
instantly perform a clean boot can prevent many panic situations.
With the bootable floppy still in the drive, copy the critical files to the floppy for possible later use, but renamed to "stay out of the way" until needed.
From the root directory of C:
C:\>copy autoexec.bat a:autoexec.old
C:\>copy config.sys a:config.old
I
Make sure you are at the A: drive prompt, with the bootable floppy in the drive.
A:\>copy con autoexec.bat
prompt $p$g
F6
The system should reply with 1 File(s) copied.
If you find that you need to boot the system from the floppy, the autoexec.bat files and the config.sys files will be available to you from the floppy by renaming them 
from autoexec.old and config.old back to their original file names. Be aware that 
if you are attempting to execute these files, only files referencing proper paths will be successfully executed. For example, if the original AUTOEXEC.BAT file read as 
follows:

PROMPT $P$G
HIMEM.SYS
\DOS\SMARTDRV.EXE 256
only the PROMPT $P$G line would execute from an A: Drive boot. Since the other two lines are EXTERNAL commands, the program calls 
must have a valid PATH. The AUTOEXEC.BAT file would look for HIMEM.SYS in the root drive of A: 
( it is in the root drive of C: ) and would look for \DOS\SMARTDRV.EXE in the \DOS sub-directory of A: (it is located in C:\DOS). The PROMPT $P$G 
command is INTERNAL, i.e. is loaded with DOS at the beginning of the boot and can be considered a "system TSR". The AUTOEXEC.BAT 
(AUTOEXEC.old)and the CONFIG.SYS (CONFIG.old) file need to be 
examined before use to correct any invalid paths and edited if necessary. The above AUTOEXEC.BAT would need to be rewritten as follows:
PROMPT $P$G
C:\HIMEM.SYS
C:\DOS\SMARTDRV.EXE 256
Be aware that if a STACKER drive is present on the machine, you will not be able to access any files on the STACKED drive without executing the line in 
CONFIG.SYS which enables the stacked volume. If, for example, your DOS subdirectory is under STACKED volume D: (a bad idea!), you would not be 
able to run EXTERNAL DOS commands from the floppy 
without first mounting the STACKED volume. For example, in the users Drive A: AUTOEXEC.BAT file,
D:\DOS\EMM386.EXE /noems
would not load if the drive is a STACKED drive OR the line
DEVICE=C:\STACKER\STACKER STACKVOL.000
had not been executed from CONFIG.SYS.
REM'ing a file
Any changes to a batch file should be done by "rem'img out the line". This process disables the program or Device Driver 
line when next invoked. It is still available when it is appropriate to enable it again. Deleting the line takes the chance that the proper path or parameter could be 
forgotten when the program or Device driver is again needed.
Placing a REM at the beginning of a line in a batch file prevents it from executing. In early versions of DOS, the user will receive a "Bad Command or File Name" 
message at boot time, but the warning is benign and the effect is the same. The 
offending (or suspected offending) line is not loaded. From within DOS 5.0's EDIT, or from within DEBUG or whatever the chosen Editor in use is, simply type 
REM at the beginning of the line to be temporarily removed e.g.,
DEVICE=C:\DOS\ANSI.SYS
becomes
REM DEVICE=C:\DOS\ANSI.SYS
and the operating system ignores the line at the next boot up. REM changes, or any changes to batch files, do not take effect until the file is run again. The actual 
purpose of the line is to leave REMarks in the batch file as a reminder of the purpose of the following line or lines, or as explanation to a future user. Do not hesitate 
to use this feature to explain changes you have made to the batch file. Example:
OLD CONFIG.SYS FILE
DEVICE=C:\DOS\ANSI.SYS
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386 /NOEMS
DOS=HIGH,UMB
NEW CONFIG.SYS
REM The ANSI driver was removed 1/1/94 to get around a BBS problem 
REM DEVICE=C:\DOS\ANSI.SYS
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386 /NOEMS
DOS=HIGH,UMB
would explain at a later date why ANSI was not loaded. 
Using DOS's Edit Command
DOS 5.0 provides a very good editor (much simpler than Edlin) that should be present for use by any user who has DOS 5.0 installed on their system. Users 
understand Edit in that it looks like a Word Perfect or other word processing program, with a menu at the top. The requirements for using the Editor effectively 
are:
*	     DOS 5.0
*	     The file QBASIC.EXE, usually under the \DOS sub directory
*	     The file EDIT.COM in the SAME sub directory as QBASIC.EXE
*	     A PATH Command to the sub directory containing EDIT.COM and QBASIC.EXE
To edit a file, in this example CONFIG.SYS, have the user return to the boot directory, usually C:\> C:\PHH>cd 
\<enter>
C:\>
type "edit" followed by the full name of the file
C:\>edit config.sys<enter>
the user should be taken into the editor and a display that looks like this:
File  Edit  Search  Options                                            Help
+-------------------------------- CONFIG.SYS ----------------------------------+ DOS=HIGH,UMB                                                                  
FILES=60
BUFFERS=30                                                                   LASTDRIVE=i                                                                  
SHELL=C:\DOS\COMMAND.COM c:\dos\ /E:512 /P                                   
device=c:\himem.sys                                                           device=c:\emm386.exe /ram 
2048                                                devicehigh=C:\DOS\SETVER.EXE                                                  
devicehigh=c:\ramdrive.sys 1536 /e                                            
___________________________________________________________________________ ª
IBM DOS Editor <F1=Help> Press ALT to activate menus         ª     N 00001:001
A cursor appears in the text screen. Edit works like a word processor, and the user can cut, copy past and perform other functions on the file. To add a CD Rom 
Device Driver, position the cursors at the beginning of the line where the device is to be inserted and simply press enter. The cursor will be on a blank line. 
Type the line to be inserted.
	File  Edit  Search  Options                                            Help
+-------------------------------- CONFIG.SYS ----------------------------------+ DOS=HIGH,UMB
FILES=60
BUFFERS=30                                                                    LASTDRIVE=i                                                                   
SHELL=C:\DOS\COMMAND.COM c:\dos\ /E:512 /P                                  
DEVICE=C:\BIN\CDDRVR.SYS
device=c:\himem.sys                                                           device=c:\emm386.exe /ram 
2048                                      devicehigh=C:\DOS\SETVER.EXE                                                  
devicehigh=c:\ramdrive.sys 1536 /e                                            
IBM DOS Editor <F1=Help> Press ALT to activate menus         ª     N 00001:001
When all changes are done, pressing {Alt F} activates the Menu.
	File  Edit  Search  Options                                            Help +------------------------------
-- CONFIG.SYS ----------------------------------+
 OMMAND.COM c:\dos\ /E:512 /P
DEVICE=C:\BIN\CDDRVR.SYS
device=c:\himem.sys
device=c:\emm386.exe /ram 2048
devicehigh=C:\DOS\SETVER.EXE
devicehigh=c:\ramdrive.sys 1536 /e 
___________________________________________________________________________ ª
IBM DOS Editor <F1=Help> Press ALT to activate menus         ª     N 00001:001
Choose S to save the document. Press {Alt F} again and choose X to exit. The new CONFIG.SYS file is saved and the user 
is returned to the DOS prompt. 
Symptom: System locks up
There are two methods to find an offending line in an AUTOEXEC.BAT or CONFIG.SYS file:
*	removing all lines and replacing them one by one
or
*	disabling lines one at a time until the offending line is found. 
The second method is quicker, the first method more thorough and more exact from a diagnostic viewpoint. If you are using the second method. remember to 
"un-REM" any line you have disabled before moving on to the next.
Continue to enable or disable device driver and TSR's from the files one at a time, re-enabling or dis-abling the last line with each edit. Try to determine the 
purpose of each line. It may be necessary for the proper funtion of the system. 
Device Drivers may perform the following functions (this is not a complete list)
*	Enable an External Floppy
*	Provide Memory Management (Himem, SmartDrv, QEMM, EMM386, etc)
*	Enable Virus Protection
*	Set DOS system preferences (ansi.sys, ega.sys)
*	Enable another Device (Scanner, CD Rom)
*	Mount a Virtual Drive
*	Mount Network Drives
because you have found the "offending" line does not mean that you have solved the problem; in most cases you must find a way to make the two co-exist. 
Autoexec.Bat loaded programs may do the following (not a complete list)
*	Provide running parameters for Device Drivers in Config.sys
*	Start Virus Protection
*	Load "Sidekick" type programs
*	Load Memory Management
*	Set System Parameters
Again, finding the offending line is not a solution, but a major clue. 
Symptom: Low Memory
Eliminating DOS=HIGH from the Config.Sys file causes DOS system files to load low; subtracting 50,000 bytes of available 
low memory. Under DOS 5.0, add DOS=UMB under DOS=HIMEM.SYS and DOS=EMM386. and try to load all Device 
Drivers high
Check memory available at any point (under DOS 5.0) by going to the DOS prompt, changing to the \DOS subdirectory and 
typing 
C:\DOS>mem /classify |more
This display will tell you, a page at a time, which programs are loaded low, which are loaded high, and the remaining 
UMB's and free Memory.
DOS 3.3 - Backup Problems
DOS's original 3.3 release had a few built in bugs. The following is recommended for any installation where DOS 3.3 is to remain on the system.
BACKUP.COM
The original release of this file, dated 3-18-87 will not properly back up disks with sub-directories. This will cause  a failure whn backing up Databases. An interim 
update dated 8-31-87 should be copied over any existing BACKUP.COM on the 
hard drive.

DASDDRVR.SYS
A BIOS problem with IBM Models 50, 60 and 80 will cause the following errors under DOS 3.30:
*       Intermittent NOT READY ERROR READING DRIVE A message during DIR or COPY commands from Drive 
A.
*       Intermittent NOT READY on floppies or GENERAL FAILURE on hard disks.
*       FORMAT fails with TRACK 0 BAD or INVALID MEDIA when responding to the prompt FORMAT 
ANOTHER? (Y/N)
*       When power is interrupted or switched on and off quickly (bad for the power supply too!) error codes 301 and 
8602 may be displayed.
The BIOS fix is a Device Driver called DASDDRVR.SYS which should be inserted into the CONFIG.SYS file as the 
first line.
CONFIG.SYS should read
DEVICE = DASDDDRVR.SYS
and the file, DASDDRVR.SYS, dated 8/21/87 should be in the root directory of the Boot Drive.
SECTION IIV - Firmware and Data Communications
PORTS
You may not be ready for this yet, but here goes. There are Ports for adding peripherals to your machine, just like you add a CD or turntable to your stereo. A 
mouse usually needs a serial port or works off of it's own card, and a printer a Centronics Parallel port. The following will NOT a full diatribe on ports, but a 
starting point.
PARALLEL
This one is easy. Plug the 25 pin end into an I/O card you have bought for the computer. Plug the weird looking end into the printer. This port is usually called 
LPT1.
SERIAL
Also known as RS-232. Usually a 25 pin connection. A little more complicated, but faster and more versatile than parallel. Don't get scared by all the technical 
jargon that comes with serial port devices.
I've rewired one ONCE for a special application, and I used to install about 400 of them a MONTH. Serial ports most often are for Mice, scanners, plotters and 
external modems and such. The serial port is the place most computer hacker 
wanna-bes have trouble. They represent 80% of my trouble calls. The first and best advice is, KEEP IT SIMPLE. DON'T mess with an IRQ that 
works, and NEVER, NEVER change the memory address of a COM port. Okay, okay, I'll back up. There are COM ports for serial devices. COM 
1,2,3 and 4. You use them in order as you need them. Usually the Modem (MOdular/DEModulator), which allows you to call Compuserve and give 
them all your money is COM 1 and the mouse is COM 2. COM 1 is, by default IRQ4 (Interrupt ReQuest 4) and COM 2 IRQ3. Each has a memory 
address. Here's the dangerous part: you are advised, in the worst pidgin English in the manual to mess with flipping IRQ and memory 
addresses and COM port assignments around. Please don't!!!!! Leave it alone. Keep it simple. Messing with them is akin to switching spark plug wires in 
your car. All you need to know unless you futz with them is:
COMMON IRQ and Memory Addresses
An IRQ is an Interrupt ReQuest to the CPU. Two devices can use an interrupt, but not at the same time. If your mouse and modem use the same IRQ, you 
will get garbage on the screen during communications every time you move your mouse. The standards are:
*IRQ1 - Keyboard
*IRQ2 - Reserved for Cascade
IRQ3 - COM2 Address 2f8 and COM4 Address 2e8
IRQ4 - COM1 Address 3f8 and COM3 Address 3e8
IRQ5 - LPT2 - If you don't have a second printer, use this for your Sound Card *IRQ6 - 
Floppy Drives
IRQ7 - LPT1 - Your first printer goes here
*IRQ8 - Clock
*IRQ9 - Reserved for Cascade
IRQ10 - AVAILABLE (scanner, CD Rom, etc.)
IRQ11 - AVAILABLE (scanner, CD Rom, etc.)
IRQ12 - AVAILABLE unless used by a proprietary 
mouse(COMPAC)
IRQ13 - AVAILABLE 
*IRQ14 - High level communications
* Leave them alone. You have been warned.
The best scenario is Modem COM1, Mouse COM2, anything else COM3 and nothing COM4, because the mouse on COM2 
will corrupt anything you use on COM4, and if you put the mouse on COM1, nothing on COM3, and something on COM4, 
the BIOS is going to ignore COM3 and put your COM4 device ON COM3. Then nothing will work.
IBM PS/2's use their own IRQ schemes, and XT's are slightly different. Your compatible, however, should be like the table above.
MODEM MOUSE WARS
Here is the MOST common modem - mouse problem and it's solution. Harry the Hack buys an internal modem for $99 from Joe's Modem Wonderland. He 
knows his mouse is on COM1, so he sets the Modem for COM2, IRQ3, address 3f8 and plugs 
that baby in. The modem is recognized by Prodigy but won't dial out, so he makes a terrible mistake - he starts flipping IRQ's and addresses and COM ports 
and gets hopelessly lost. He either gives up or takes the machine to Joe, who charges him $125 and refuses to tell him what he's done.
What's happened is that the mouse is indeed on COM1, but there is also an active COM2 on his I/O card, and, even though nothing is hooked up to it, the 
BIOS thinks that two devices are hooked to COM2. What is necessary is to either jumper out COM2 entirely on the I/O board or set it to COM4, address 2e8 
instead. COM2 is now free for the Modem. A better 
solution is to move the mouse to COM2, change COM1 on the I/O card to COM3 and put the modem on COM1. That way you avoid the 
problem of a blank COM3 being taken over by COM4. End result: Modem COM1, Mouse COM2, Nothing (but recognized) COM3. End of 
problem.
Don't call me if you mess with IRQs and Memory addresses. It gives me a headache. If you futz with the memory address, I won't even talk to you at the 
Christmas Party.
To summarize, put in the I/O board, hook up your printer , call it LPT1, hook up your preferably internal modem as COM1, IRQ4 and your mouse as 
COM2, IRQ3 then leave it alone. You have been warned.
MODEMS
Modems are a pain in the butt.
Modem Basics
Communication from computer to computer may be accomplished a number of ways, including LAN connections, direct computer to computer hardwiring 
or over a Modem. A Modem is a MOdulator / DEModulator that converts signals from a HOST computer from digital signals (0'as and 1's) to an analog 
signal usable by telephone lines. (Telephone lines will 
eventually be digital, making communications simpler, quicker and purportedly cheaper.) The receiving computer converts these analog signals back to digital, 
and sends information of its own back to the HOST using the same conversion process; the two computers, therefor, are MOdulating and DEModulating the 
information traveling over the phone lines. 
An External Modem is a physical device attached to a serial port of the PC. An Internal Modem is inserted into the Motherboard of  the computer. An 
External Modem  has a power cord or plugs directly into the wall- it is not powered by 
the Computer. There is usually a number of Lights that activate as the telephone line becomes live (dial tone), information passes back and forth between your 
computer and the Host, and as other activities occur in the Communication session. You should watch these lights and become familiar with normally occurs 
during a Communications session.
An internal modem is powered by the Computer and no AC cord is needed. There are no lights, which is a disadvantage for diagnosis of problems.
Both Modem types require that a telephone line be connected from the Modem to a telephone jack. Most Modems have two female jacks in the back; they are 
usually marked "line" and "phone." On most Modems (but not all) these jacks are not interchangeable. You must make sure that the "line" jack is connected to 
the wall jack. The other jack is to hook up an optional telephone. If you have only one phone line, this allows you to use a phone when the Modem is not in use. 
Never pick up the phone while a Communications session is live. If you have more than one device that uses the phone line (such as a separate Fax Board) it 
may be run in-line with the modem. A typical connection might be:
*        A line from the wall jack plugs into the "line" jack of the Modem.
*        A second line runs from the Modem "phone" jack to the "line" jack of the Fax.
*        Still another line runs from "phone" on the Fax to the "line" jack of an answering machine;
*        A final line runs from the "phone" jack of the answering machine to the telephone.
You can see that many devices can be placed in a straight line from the wall jack to the end device. Attach each device in 
sequence, checking for a dial tone at each step.
NOTE: Be aware of device contention: if more than one device has the ability to "answer" the phone, you need to build in a line discriminator device, or set 
the number of rings before answering on each device. Set your Modem to NOT Auto-
Answer until that feature is required.
Modem Speed
Modems operate at a speed measured in Bits Per Second, or BPS. The term Baud is widely used and is technically incorrect. Most Modems in use today are 
2400bps, though SALES of Modems are overwhelmingly 9600 and 14,400.. Your Modem 
may be slower or even faster. The usual speeds are 300bps (outdated and too slow for our uses), 1200bps (very common in the 80's), 2400bps, 4800bps (used 
in Data Centers for the most part), 9600bps and 14,400bps, the new standard, which is the same speed your fax machine probably uses. 9600bps and above 
speeds can use the MNP4 error correcting protocol  and MNP5 Compression which allow our noisy, slow telephone lines to handle this quicker rate. MNP5 
Compression can allow 
two 14,400 bps Modems to exchange information at an effective rate of 56,000 bps. Most users still have 2400 bps Modems.   Digital telephone lines will 
operate at 64,000bps and eliminate the meed for Modems!
Your Modem documentation and possibly the Modem itself will tell you the BPS of your Modem. It is important that you configure your Communications 
Software for the correct BPS. It is usually advisable to set the BPS rate of the Port HIGHER than the speed of the Modem If you set the BPS rate slower than 
optimal, and your valuable time and long distance dollars will be wasted. New High Speed (9600+bps) Modems have auto-fallback, which reduce the speed 
automatically. In the 
event of noisy phone lines during a storm or over a great distance, the "node" on which your telephone signal is being carried may have too much 
distortion for your Modem  to send and receive clear signals; you will get numerous error 
messages (especially during file transfers) and possible "screen garbage."  In this case, first try logging off, hanging up and re-dialing and hope for a cleaner node. 
Failing that, it is possible to reduce your baud rate in the configuration screen but not below 1200bps. Slower communications are generally clearer.
Hardware Types and Placement
The Modem is either plugged directly into the motherboard (an Internal Modem) or connected over a Serial Modem Cable 
that is plugged into an RS-232 port on the back of the computer (an External Modem). Using a special purpose cable (such as a Serial Printer Cable), or a bad 
cable is a cause of a large percentage of communication failures. In the event that  communications should work and don't, replacing the cable with one "fresh 
from the bag" is a good starting point for troubleshooting when hardware is suspected.
 Physical Checks
-Telephone Cable
Verify good connection of all jacks and continue:
*		Is the cable to the wall jack connected to "To Phone" (or Tel) rather than "Line"?
		Remedy: Connect "Line" cable to wall jack.
*		Look closely at the (RJ-11) plug connected to the "Line" input of the Modem; does it have four copper bands or just 
two? If two, go to Remedy. Repeat for wall jack.
		Remedy: Replace cable with four band cable.
*		Look closely at the copper bands on the plug connected to the "Line" jack of the Modem and the wall jack. Do the 
wires appear bent, concave or covered with a translucent film?
		Remedy: Replace cable
*		Do you have more than two phone lines? If so, it may be a non-standard phone jack. Some Modems need to be told if 
they are connected to an RJ-12 or RJ-13 jack rather than the standard RJ-11. Hayes 1200 Modems, for example, need to have Switch 7 set to DOWN for 
other than RJ-11 jacks. Incidentally, a Hayes SmartModem with no BPS identification  
is a SmartModem 1200.
		Remedy: Per the Modem 
documentation.
DB25 and DB9 Connectors
If you are working with an external 
Modem, Required Pins for a DB-25 
cable for use with a Modem
	1-GND	     5-CTS
	2-TxD	             6-DSR
	3-RxD	             7-GND
	4-RTS	     8-DCD
			20-DTR

*		Check the connectors at both the Computer and the Modem. Do the Male pins on the Computer and the Modem end of 
the cable appear straight? If not
		Remedy: Carefully straighten pins or replace cable
*		Are any pins missing on the male end of the cable? If so,  the cable may be made for a special purpose.
		Remedy: Replace cable temporarily and retry  communications
*		Does the cable say "Null" or "Null Modem" on the connector or the cable? If so, this cable is intended for direct  
computer-to-computer hook-ups (e.g., PC to Laptop). Note: Most Null Modem Cables are unmarked. The user will not 
be able to tell.
		Remedy: Replace cable
*		Is there a small connector "hooked on" to either end of the cable? Examine it closely. It may be a gender changer, null 
Modem adapter or for some other specialized serial device, such as a  printer.
		Remedy: Remove the adapter or replace the cable
Required Pins for a DB-25 To 
DB-9 connection 
	2-TxD	             6-DSR
	3-RxD	             7-GND
	4-RTS	     8-DCD
	5-CTS	   20 DTR
			22-RI
The usual Modem to CPU Cable is a DB25 Cable with 25 pins. Only nine of these pins are in use. With the introduction of Laptops and IBM PS/2's with 
small footprints, the 9 pin Serial Port came into favor. If the Serial Port on the user's computer has a nine pin input, there may be an adapter which changes 
the DB25 pin connector on the Cable to a DB9. This will not adversely affect the connection, as only 9 pins are used in Serial transmission.
In any event, while troubleshooting where there seems to be nothing getting from the external Modem to the computer, replacing the cable with one new 
from the bag or known to work would eliminate most of the  problems above.
If changes are made to an I/O board or internal Modem to enable or change a Com Port, please remember to have the 
User turn the equipment all the way off and then power up again. Re-booting the machine WILL NOT reset I/O 
changes.
Other devices using Serial ports are Serial Mice (bus mounted Mice generally stay "out of the way" of serial communications; their IRQ settings may usually 
be checked on the mouse board itself), Plotters, hand held Scanners, Fax Modems, Serial adapted Printers, Laser Printers and others. It is usually preferable 
to assign the mouse and the Modem to Comms 1 and 2, with other devices occupying Comms 3 and 4. 
The BIOS
The computer itself recognizes (or fails to recognize) Com Ports through it's BIOS, or Basic In Out System. The "set-up" that is entered by a key 
combination while the computer is booting, or the "set-up disk" provided with the computer will usually report which Ports the computer recognizes; if it 
only reports one Com Port and you have two devices connected to Serial Ports, you need to solve this before moving on to anything else.  The BIOS may 
report only one Com Port because
*		 Both Ports are configured as Com 1 or Com 2
*		 One of the Com Ports has not been enabled (a dipswitch or jumper setting on the card)
*		The second serial port on an I/O card has not been purchased, i.e., some cards have connections for two serial ports, 
but, in order to use the second, a set of chips needs to be purchased and inserted on the card. You will notice empty sockets on the I/O card.
*		 The BIOS simply needs to be re-initialized. If a new device has been added, and the user ignored the BIOS request to 
enter set-up, the information that the Port is there may need to be recognized and saved by the BIOS. This is especially true if BIOS set-up is on a floppy disk. 
IBM and Compac both use set-up disks rather than Hardware based set up.
 Many I/O Boards and combination Drive & I/O Boards ( such as Morse IDE Controllers) take Com 1 & 2, forcing the user 
to allocate an internal Modem to Com 3 or Com 4, even if  no device or only one device is used on the first two ports. If the Mouse is on Com 1, the user in this 
case must assign the Internal Modem to Com 3 or higher.
The BIOS: Com 3 and Com 4 
Many BIOS sets, including AMI ( on many clones) map Com Ports as they find them. If a device is hooked to Com 4 and 
Com 3 is unassigned, the BIOS sets in question will recognize the Device as Com 3, even though it is using Com 4 address 
and IRQ. This will cause a hard to detect problem where everything else seems okay.
Diagnostic Utilities and Tests
There are many fine diagnostics products (such as Checkit!) on the market that will help identify the devices mapped to 
Com Ports and allow testing of throughput; there are also diagnostic routines and test hardware (such as loop back testers) that will allow the "power user" to do 
their own testing. We will shortly be providing you, or have recently provided, a utility diskette for your use in the field. To the user, especially when using phone 
support, there is a need for simplified testing. The five following tests will help determine whether the user's hardware can be bypassed as the problem source:
!TEST ONE: Testing DOS's recognition of the existing Com Ports
To do a simple test to see if DOS is recognizing a Com port, go to the C:\> prompt and in the root directory of their hard drive (or A:\> if no hard drive is 
present).
Type
C:\>copy con a.tst <enter>
	*i.e. type "copy con a.tst" at the prompt and press enter. 
This begins creation of a file, "copied from the console (keyboard) a file named a.tst". The user should now be at a blank line under the prompt
Type
test <enter>
	*the user types the word "test" and presses enter.
Press F6 <enter>
^Z
	*press the F6 function key, which produces the ^Z, or end of file marker. DOS should respond with
1 file(s) copied
	and returns the user to the DOS prompt. 
The second step is to copy these files to the Com port devices that, if they are present and recognized by DOS, will reject or print the file. Again at the C:\> 
prompt,
Type
C:\>copy a.tst Com 1 <enter>
One of three things should occur: 
*	   the file will be copied to another file named "Com 1" indicating there is no Com 1 recognized by DOS
*	   the output will go to a printing device (indicating a printer or plotter attached to that Com port) or 
*	   DOS will return the following error message:
Write fault error writing device COM 1
Abort, Retry, Ignore?
(result may be slightly different in different DOS versions.) 
This error message indicates that SOME device (mouse, Modem, plotter, etc.) is recognized as "owning" Com 1 (has 
rejected the input) and you can assume that a device is connected. Press A for Abort to get back to the DOS prompt. Repeat the test for Com 2, i.e.,
C:\>copy a.tst com2<enter>
Again, if "1 file(s) Copied" is the result, DOS recognizes nothing as being attached to the port. If the file is sent to a serial printer or if the "Write fault error" message is 
returned, DOS does  recognize a Device on the port.
Repeating the test for Com3 and Com4 may find the Modem where the user did not expect it to be... they may have assumed 
that  the device was using 1 or 2.
To further this test, the user can disconnect serial devices until only the Modem remains, and repeat the test.
!TEST TWO: Using Debug to identify Ports
If you are comfortable with DOS's DEBUG.EXE, the following is a very quick and very accurate test of what Ports the Machine "thinks" it has:
from the DOS prompt in the DOS SubDirectory, type Debug <enter>
C:/DOS> Debug <enter>
the screen will respond with a "dash" prompt
-
at the "dash" prompt, type "d40:0 <enter>
-d40:0 <enter>
The system responds with a listing of the BIOS data showing occupied Com and LPT (printer) ports.
The table (with the user's BIOS settings) will look as follows:
0040:0000	00 00   F8 02   E8 03   E8 02       -   BC 03   78 03   00 00   00 00
Com Ports are on the left of center, addresses in reverse, Printer Ports are on the right, as follows:
	Com1    Com2    Com3    Com4            LPT1    LPT2    LPT3    LPT4
0040:0000	00 00   F8 02   E8 03   E8 02       -   BC 03   78 03   00 00   00 00
This test shows NO Com1, but Com 2, 3 & 4 recognized. The numbers represent the hexidecimal address of  the Port. This is a great place to see if the 
user has default Com addresses. This test could show that the I/O board or Internal Modem jumper has configured the Modem as Com3, while the user 
assumes the Modem is on Com 1.
The "dash" prompt returns, where the user types Q to quit Debug.
- Q
returning to the DOS prompt
C:/DOS>
!TEST THREE: Testing the outgoing line
Start a communications program and get to the terminal screen. Type ATDT15551212 (any number will do to test the 
Modem's dial out capabilities. The call should be aborted by pressing any key as soon as ringing begins) and, if the dial tone begins and the number is dialed, we 
know that the Modem is functional and hardware parameters (but not necessarily the Communications parameters) are probably correct. Press a key to stop the call. 
This test should work on Modems using the 
AT Command Set or a derivative, which is most Modems. 
*If the characters are not echoed to the screen as the user types, there is a strong possibility that the Com Port is set wrong. You may also have two devices 
competing for use of this Port.
!TEST FOUR Com Parameters and Line Noise
If characters were echoed to the screen and a dial tone and numbers dialing were heard, call a bulletin board.
If a connection is made and garbage begins scrolling across the screen, watch the garbage carefully: is it a steady stream, or do recognizable words from the menu 
appear followed by random ASCII characters?
If there is a steady stream of garbage, (usually ending at the far right column of the second or third line on the screen and continuing there, overwriting letters at a 
rapid rate,) the Communications settings are probably wrong. Enter set-up (for the Communications program and check all parameters. Most on-line services use 
8n1 (Eight bits, No Parity and 1 Stop Bit), 
and a helpful fellow user may have changed the settings.
Improper Parameters might look something like this on the screen:
Connect 2400
AAAAAAAAAAAAAAAFFDF$%^$^%&&%^%^&                                                   
$%#$%$%#######%^&^&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&@
with the cursor pegged in the rightmost column.
If the garbage is intermittent, you have a noisy node from the telephone company, a cable is loose or bad, or noise from something in their environment is in the 
phone line. Check connections and call in again, hoping for a clearer node. If the problem persists, the user may enter set-up and try slowing the 
communications speed from 9600 bps to 4800bps, 2400bps 
to 1200bps, etc., but not below 1200bps.
!TEST FIVE: Line Noise Isolation
Call a local Radio Shack and ask for the number of a local BBS. A BBS or Bulletin Board System is a great place to test Communications. 
Type 
ATDT (or ATDP if you have a Pulse Dialing system),{prefix} (such as 9 for an outgoing line) xxx-xxxx.,<enter>.
If you make a successful connection to the Bulletin Board, follow the prompts for a minute or so and watch for screen garbage. If none occurs, the 
problem was line noise.
A typical successful session (with user's replies in bold) might look like this: 
___________________________________________________________________
Press (ESC) to enter the Bulletin Board
(ESC)
Welcome to CHICAGO'S FINEST BBS Operating Wildcat Version 5.3
Enter NAME or New: John Smith
John Smith is not in my files
Enter NAME or New: New 
Your Name: John Smith
Calling From:Anytown, USA
John Smith         calling from
Anytown, USA
Is this correct?:(Y, N, Quit): Y
Welcome to Chicago's Finest BBS. As a new user, you will be given limited access rights. Feel free to browse the Board, and register at 
any prompt by typing R.
Choose a Password:
At this point, you should hang up by disconnecting.
Intermittent screen garbage associated with line noise might look as follows:
Welcome to CHF#$%@ICAGO'S FINEST BBS! 
Op#@%$#$^$@#!$@$~~~~))) Enter NAME or New: ^#$%&*(
^#$%&*( is not in my files
Enter NAME or New:$%$#@*&^
Unauthorized User; Disconnecting
%&%&$%^&
NO CARRIER
Figure	4.3 Testing over a BBS: Line Noise
 If screen garbage has disappeared when calling a local service, the long distance Node (and how the Modem attempts to deal with it) is the problem. A 
dedicated Modem line may be helpful, but does not guarantee error free Communications. Line Noise Remedies
A line-noise filter, or toggling the Hardware and Software Flow Controls on and off  under set-up may help the problem, or increase it. Try with the Hardware and 
Software Controls turned on and off. Software flow controls can get "stalled" by line noise. If the Modem itself  has settings for Error control, disable it 
temporarily. Many earlier Modems with Error Control built in would not allow a call to continue if it did not meet it's Error-Free standards. As soon as connection 
was made, the Modem would hang up. Disabling these via dipswitches per the Owner's Manual may be necessary. 
Modem Lights
Modem lights on an external Modem can give us clues that the Modem is or is not responding. The Modem lights 
commonly on PC equipment will be similar to the following list:
*HS	        A Modem is operating at or above 2400bps. A very old Modem might use   
	this light to indicate 1200bps versus 300.
*AA	        A Modem is set to Auto-Answer mode. 
*CD	        If no call is in progress, this light may inform you that CD is set to high,    
i.e., the Modem is forced to recognize Carrier Detect as being true,      in effect that a 
dial tone exists when one does not. User needs to                               disable by changing a hardware or software setting. On some                            
Modems, switch 6 has been enabled (UP). Change to Down. Used                              in synchronous (direct) communication. 
*OH	        The line is Off Hook
*RD/RXD Computer is Receiving Data
*SD/TXD Computer is Sending Data
*TR/DTR Data Terminal is Ready. Program has activated Modem.
*MR/DSR Modem is Ready. 
*CS/CTS Clear to Send. On during Synchronous (non-telephone line) sessions.       
	The local Modem sends this to the remote and waits for RTS.
*RS/RTS Request to Send. Acknowledgment by the local Modem of CTS by the          
	remote. Modem is on and ready.
An idle Modem will generally illuminate MR, HS (unless set to low speed by switch).
Modem Switches
Most older Modems have a set of dipswitches to provide Hardware control of Modem Functions. They may be located in the rear of the unit or  behind 
the translucent face plate of the Modem. This face plate is removable by inserting a small 
screwdriver or ball-point tip of a pen into a slot on the translucent plastic panel. If no slot is visible, assume that the dipswitches are not located behind that panel. 
If all settings and other hardware seem to be correct, but the Modem will not function properly, a dipswitch may be set that is interfering with the proper response 
of the Modem. There is no substitute for the Modem Manual short of a technical call to the Modem Manufacturer. For reference, the following is a description of 
the switch bank of a series of Smart Modems, provided by Hayes:

CD High
If all hardware connections seem to be in order and properly configured yet you can't get past the dial tone, CD may be set to high. First check that CD is set to 
"not forced", then check to see if the DipSwitch on your Modem that controls CD has been set to high. If more than one person uses the machine, or if direct 
computer to computer communications is sometimes done over the Modem, CD may not be set "not forced". CD High may also be used in a Modem Pool setting 
where the 
Carrier is already present.
Com Port
If the Com Port seems to be set correctly in both PC Hardware and in the Software, and you still have reason to believe that the wrong Com Port is being 
addressed, check the dipswitches on the external modem, and check the documentation for an internal modem for a Com Port Jumper. A jumper is a small piece 
of plastic that slips over two copper pegs. There are usually three pegs, and placing the plastic jumper over peg one and two may enable Com 1 and pegs two and 
three enable 
Com 2. 
Physical Adjustment of Modems- DipSwitches and Jumpers.
N.B. Do not change a jumper setting or a DipSwitch without benefit of the Modem Manual. If you decide to make a change, 
that is, you are fairly certain that there is no other cause for the Communications failure, first make a drawing of the current configuration, noting the position of each 
switch or jumper, and orienting that to the position of the equipment. In particular, make sure the user is comfortable with which position is on (up or down), and 
which is off. A 0 indicates off, a 1 indicates on. 
DipSwitches: 
After noting current positions of all switches, insert the point of a ball-point pen below the toggle portion of the switch or in the hole indented into the toggle of the 
switch. Push the switch towards the other position until a "click" is heard. Turn power to the Modem off and on again for the change to take effect.
Jumpers: 
Be sure your user is comfortable doing this. Power to all equipment should be off. Label and then disconnect any cables necessary for removal. Remove the Internal 
Modem or I/O card by removing the retaining screw where the card is attached 
to the frame. Pull gently and firmly straight up from the Motherboard. Place the card on a flat, soft surface such as a piece of cardboard. Watch for sharp solder 
points on the reverse side of the card. Remove the jumper by carefully pulling straight out from the posts using a pair of small needle-nose pliers. Be aware that the 
jumper is extremely small and light, and very prone to dropping and loss. It is near impossible to find a jumper that has fallen on the floor. Replace the jumper in it's 
new position by carefully and firmly pressing the jumper over the new set of posts. Make sure that the jumper slides OVER and 
not to the side of the post.
Replace the card in the Motherboard slot by aligning the gold card edge on the bottom of the card with the same empty slot 
in the Motherboard. Press down gently and firmly. Do not force the card. Rock gently back and forth until the card is firmly seated. Replace the retaining screw 
and reconnect any cables. Check the work and power up the equipment.
 Communications Protocols
This is an overview of some hardware basics so that when you are reading the specifications of your Modem, you will have 
a general understanding of whether those specifications have a bearing on the Troubleshooting process.
ARQ 
- Automatic Request for Repeat - causes the receiving Modem to request re-transmission of garbled Data until the correct data is received, or until a maximum 
number of retries is reached.
baud
 - The number of symbols per second, which are made up of a number of bits - a 9600 bps Modem may still operate at 2400 baud. E. G. If you were passing half 
full buckets of sand through a window at a rate of 50 buckets per hour, increasing the amount of sand in the buckets would not affect the number of buckets 
passed, just the volume of sand coming through. Increasing Modem speed involves passing more bits in the same number of symbols. The speed is finite, topping 
out at around 28,800 bps due to the limitations of analog phone lines and serial ports.
bps
 - Bits per Second - The speed of the Modem
CCITT
 - Compliant ratings of Modems that tell you some of the inherent features
CCITT Standards - CCITT is a U.N. Sponsored organization responsible for International Telecommunications Standards. They pass on proposals from 
developers that lead to the "V Dot" Series standards such as V.32bis.
ISDN
- Integrated Service Digital Network - Digital lines will replace Analog lines for all telephone services, making many 
Modem requirements obsolete - they will not have to MOdulate and DEModulate the signal, and line noise will be dramatically reduced, much the same as 
the click and pop of analog LP records was replaced by the clarity of the CD, a 
digital device. The conversion process will be akin to the laying of home TV cable - fast in highly profitable and accessible markets, slower in poorer or 
complicated Markets. Eventually, your analog phone equipment will have to be replaced, but 
the new equipment will have voice, data, photo, multiline  and other capabilities. It will even be possible to transmit Data and talk (with live video) at the same 
time, using different frequencies. ISDN will not replace Modem Communications anytime soon, but some Modems may claim to be ISDN compliant.
ISO
 - International Standards Organization. 
LAPM
 - Link Access Protocol\Modem - A compression scheme which can send ASCII Text at up to 4 times the normal rate, and 
which is intelligent enough to bypass already compressed files such as ZIP's ( a very common compression scheme which ZIPs files to save room on 
disk and time in transmissions).
MNP
- Microcom Networking Protocol - error detection schemes developed by Microcom, which releases MNP standards to 
public domain after Microcom has supplanted them. MNP 1 through 6 can be found on many brands of Modems, while 
MNP 7 - 10 are found only on Microcom and Microcom licensed products. MNP error correction will be used by Communications programs to the 
highest common MNP. If your Modem has MNP 3 and mine has MNP 4, the 
Communications will be established at MNP 3.
MNP1
- Asynchronous, byte oriented, half duplex. About 70 % efficient, allowing a 2400bps Modem to transfer at about 
1690bps. Now dated and uncommon.
MNP2
 - Full Duplex data exchange. About 84% efficient, for 2000bps on a 2400bps Modem.
MNP3
 - Synchronous exchange. In Asynchronous Communication, 10 bits are transmitted for each 8 bits needed, with 
the other two bits transmitted as stop bits (here it comes, there it goes). Class 3 MNP does not use these bits, resulting in faster throughput. 108% 
efficiency (with no MNP being 100%), means throughput of 2600bps on a 2400bps Modem.
MNP4
 - Uses Adaptive Packet Assembly and Data Phase Optimization. During Data transfers, MNP Monitors the 
reliability of the transmission. MNP will assemble larger packets for transmission if the lines are clear enough to warrant it. The efficiency is about 
120%, or 2900bps throughput for a 2400bps Modem.
MNP5
 - Adds Data Compression. Works on Terminal conversation as well as Data transfers. Compression will range 
from 1.3 and 2 (that is, fitting 130 to 200% into the space normally occupied), depending on the source. Text files such as this have many blank 
spaces between words, lines, paragraphs and pages, and compression squeezes out those blanks and then expands them again at the other end. This is 
the same method employed by Stacker and Zip files, as well as those compressed files on installation diskettes with large programs (e.g. Windows 
3.1). The average compression will cut time by an average of 63%, which is the equivalent efficiency of 200% over a non 
MNP Modem (which, as you recall, operates at 70%.) So the throughput of a 2400bps modem with MNP5 is 4800bps.
MNP6
- Uses Universal Link Negotiation  and Statistical Duplexing. ULN allows an MNP6 Modem to "step up" the 
Modem on the other end to a higher protocol. Hence, many less expensive Modems will claim to be MNP6 Compatible! UNL Modems 
begin at a low speed of transmission and then "negotiate" higher speeds with the other modem. Statistical Duplexing monitors the 
transmission and allocates resources. MNP6 throughput on a 9600bps Modem can reach 19,200bps.
OSI
	- Open System Interconnection Model - Complies to ISO standards.
V Dot Standards: 
V.17
 - Developed for Fax Machines as their 14,400bps standard. Uses half duplexing, since Fax transmissions are 
mostly one way.
V.32
 - Released in 1985, the standard for 9600bps Communications. 
V.32 bis
- bis is French for second. A third release would be named V.32 ter, French for third. V.32 bis is the standard for 
14,400bps. Released in March, 1991.
V.42
 - Includes MNP4 state of the art for error detection and correction. 
V.42bis Incorporates two levels of data compression; MNP5 and LAPM, which is Link Access Protocol\Modem.
V.fast
 - Yet to be released standard for 28,800bps Modems.
The AT Command Set
This is an abbreviated reference chart of the AT Command Set. Many AT Commands will never be used, and this list attempts to limit the information 
to that which will be of most use.
This is the Hayes Command Set, which is used by the vast majority of Modems. You will find that most modems use a subset of these commands. An 
older or less expensive Modem may use a smaller subset of the Command Set than a Hayes Product. AT Commands you would be likely to use are 
most likely supported on the Modems you will troubleshoot.
Typing "AT" in the terminal mode of Communications Software means "Attention Terminal!", literally, wake up! It tells 
the Modem that the Command following the attention signal is for it to act on. Typing AT <enter> by itself should produce an OK (i.e. "I'm awake"). 
Fortunately, it is unnecessary to follow AT with a cup of coffee and a donut. The attention signal is sufficient.
Hayes Command Set (Abridged)
AT	Precedes any Command except A/, A> and +++. AT by itself should return "OK".
Exceptions (as above)
A/	Send the last Command again. AT or <enter> not required.
A>	Send the last Command continuously until a key a pressed. Dial strings are executed ten times. AT or <enter> not 
required.
+++	Hang up.
All commands in the following list will be preceded by AT. 
DP
would mean that you would type ATDP (Attention, Terminal, Dial a Pulse Number)
AT Commands
A	Force Answer mode. Example: ATA or AT A. If your Modem is ringing and you want to pick up  the line, 
type ATA in terminal mode.
Bn	Handshake options
	B0	V32 modulation, 9600/4800bps or
		CCITT V.25 answer sequence. Courier Modems overseas.
	B1	HST Modulation 14.4K - 4800bps or
		Bell answer tone, US and Canada
Cn	Transmitter enabled/disabled
	C1	Transmitter disabled; receive only
	C2	Transmitter enabled; default
D	Dial the number that follows, enter originate mode. Options:
	P	Pulse Dial
	T	Tone Dial
	,	Pause 2 seconds
	"	Dial the letters e.g. ATDT 
1800"COMPUSRV"
	!	Transfer call
	W	Wait for second Dial Tone (X3 or 
higher)
	@	Wait for an answer (X3 or higher)
	R	Reverse frequencies
	Sx	Dial the number in NRAM
S1 First stored number
		S2 Second stored number
S3 Third stored number
En	Local Echo
		E0      Commands not sent to screen (used in scripting)
		E1      Commands echoed to screen (default)
Fn	Duplex Mode
	F0	Echo Off.       (half  duplex) What you type is not returned    from the remote.
	F1	Echo On (full duplex) What you type is returned from the remote.
If a user tells you that everything they type comes out double on the screen, e.g. LLOOGG  IINN??, the Modem is set 
to Full Duplex. Sending ATF0 at the Communications screen would do the same thing for the current session.
H0	Hang up (off line)
H1	Go off hook (live line)
In	Inquire of Modem 
	I0	Display product code.
	I1	ROM Checksum
	I2	RAM Test
	I3	Call Duration or Time
	I4	Current Modem Settings
	I5	NRAM Settings (stored information)
	I6	Link Diagnostics
	I7	Product Configuration
K0	Modem Clock: Call Duration (default)
K1	Modem Clock: Real Time 
Mn	Speaker Control
	M0	Speaker off
	M1	Speaker on till after handshake (default)
	M2	Speaker always on
	M3	Speaker on after last digit till after handshake
O	Return on line after Command
P	Pulse Dial 
Q0	Result codes displayed
Q1	Result codes suppressed
Sr=n	Set S Register. r is register, x is number between 0 and 255.
Sr.b=n  Alternate, uses bit mapped registers.
Sr?	Query contents of register r
T	Tone Dial e.g. ATDT
V0	Return result codes numeric (028)
V1	Return result codes as words ("busy")
Xn	Set how "smart" a modem operates
The X Value
The higher a modem can be successfully set, the more information it can return. The following chart shows features available under each option. Most 
initialization strings set the modem to X4. X6 is optimal, but many Modems only support 
X1-4.
The Extended Command Set
The Extended Command Set is not as standard as the Hayes Command Set, but is similar across most Modems. The syntax is again AT followed by 
the Command, in this case &nn...
Command/Options
&Cx	Data Carrier Detect options; &C1 is most common
&Dx	Data Terminal Ready Options; &D2 is most common
&F	Reset everything to factory settings. Only do it if you mean it. ATZ is usually a better choice.
&G	Guard tones. &G0 is usual
&L	Leased or dial up line. &L0 is usual
&M	Synchronous or Asynchronous - Synchronous is for direct connections. &M0 is usual
&P	Pulse dial ratio - &P0 is usual except in Hong Kong and London.
&Q	Same as &M
&R	Synchronous RTS/CTS. Not used in async
&S	Data Set Ready. &S0 is usual
&T	Diagnostic tests
&V	View stored configurations
Modems 9600 and above will have their own AT sets depending on brand. This is a disgrace in the industry. Modems may use AT/n, AT*n, AT%n, 
AT-n, AT"n, etc. You have to spend time with your modem manual.
A good start for clearing up communications problems is to type the following in Terminal Mode:
ATZ (reset the modem)
OK (response from modem)
AT&c1&d2 (set carrier and data set)
OK
If that seems to solve your problem, send
AT&W (write this as a default)
OK
If that doesn't do it (for example, you connect and immediately hang up) type this line
AT&F&C1&D2&W
If that doesn't do it, you must type
AT&V
which, if your modem is semi-normal (not including Hayes Sportster, by the way) will send a list of all parameters in effect to the screen. Print this out and sit 
down with your Modem Manual
Error Correction and Compression
Most 'can't connect' ills are caused by 1)compression or 2) Error Correction negotiation failing. To get a good connection with a service, use the same technique 
I tried to teach you in this book for hardware - additive diagnosing. Use your modem manual to TURN OFF compression, then try again. Compression DOES 
NOT WORK on 95% of BBS's and OnLine 
Services. This is because most files transferred are ZIPs, which are already compressed. Use your modem manual to next turn off LAPM and other error 
correction schemes and try again. Next turn off Hardware and Software Flow controls, XON/XOFF and RTS/CTS and try again. Get the modem down to as raw 
a connection as possible, and when you find a configuration that works, type AT&W to save it, then add the above stuff back in one at a time to isolate the 
problem.
When you leave one communications program (such as Prodigy) and go to another (such as ProComm Plus), reset your 
Modem by typing ATZ. Some programs, most notably America On-Line, set your Modem back to Factory settings by sending an AT&F. This is a 
nasty practice. ATZ is what sets your modem back to YOUR normal defaults. AT&F blows that away. Find out what settings you need for America 
On Line, then go into Setup, Setup Modem, Modem Commands and change the AT&F to ATZ in both the initialization string and the Modem Reset 
string. A sample initialization string, before and after: (Intel Satisfaction Modem)
before: AT&F%c0\g0\q0\m0^m
after:ATZ%c0\g0\q0\m0^m
Another exception that may be archaic is Compuserve. I haven't connected to them in years, but you use to have to set your modem to 7 data bits, One Stop 
Bit, Even Parity to connect to them. Normal BBS's and OnLines use 8 data bits, One stop bit, No Parity.
INTERNET
Wow, what a buzz word this has become. What is the Internet? It's a largely ungoverned, loose set of communication lines 
that originally was intended for business but is largely used and controlled (or uncontrolled) by colleges, notably Stanford, USC, etc. You can send mail, join 
conferences, download files, chat, etc. over various Internet nodes. Navigating the Internet is incredibly complicated. Like UNIX. The US Information 
Superhighway is coming that will give us all access to each other over a common trunk. Hopefully, this will not turn into a Federal boondoggle that miserably fails 
or prices you and me out.
A practical way of using the Internet is by joining America On Line; I have been a member since the 80's, and have gone through and dropped Prodigy, Delphi, 
Genie and Compuserve in it's favor. America On Line allows you to send Internet 
Mail for free (over and above normal connect charges). Prodigy charges you just to read incoming mail. Delphi will give you real live Internet access, but I 
find it not worth the price or aggravation.
An emerging standard is Microsoft Mail. I think within two years, most people will have an Internet Address and Microsoft Mail or a compatible. My Internet 
address is ElectrkBlu@AOL.com, and within 3 months, I will have an address at work. Right now we are working on putting in the Gateway. You can write 
to all kinds of interesting people just by knowing their Internet address. Write to Billy boy Clinton; you can write to Tom Brokaw at NIGHTLY@nbc.com. 
Lists of Internet addresses are springing up everywhere. Write to anyone on Prodigy just by knowing their USERID. For example, you can write to my dear 
brother at SBNJ66A@prodigy.com. Tell him Mom liked me best.
Learning communications over the Modem is the single most forward thinking thing you can do on the Computer to 
prepare to be useful in the 90's workplace. I urge you to fire up a modem and learn.
You've mercifully reached the end of Version 3 of Build-it. I hope you use and re-use this document for a long time to come, and that you pass it on to friends.   
--DJ Elliott, December,1993
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