ÚÄÄÄÄ ÚÄÄÄÄ¿ ¿ Timothy Harris ³ ³ ³ ³ 5 Burnham Park Road ³ ÃÄÄÄÄ´ ³ Peverell ÀÄÄÄÄ ³ ³ ÀÄÄÄ Plymouth, ÄÄÄÄÄ ÄÄÄÄ ENGLAND, PL3 5QB v3ú21 THarris@UK.AC.PLYM.SC To execute CAL type `CAL' with the current directory set to the one in which the CAL.EXE, CAL.OVR and CAL.CFG files reside. CAL will run on a floppy-disk-only machine but copying all the files to the hard drive and executing them from there (run `INSTALL.BAT' to do this for you) will allow for quicker access to the help information. CAL is public domain and you are therefore encouraged to give copies of it to other people - however these copies must be in an unmodified form and any charge made must be for media and distribution costs only. The latest version is available from me on receit of a blank disk and SAE, or a cheque for œ2ú20 - remember to specify what type of disk you are using. Hardware requirements: CAL will work on almost any machine described as `PC-Compatable' that uses the DOS operating system. A maths coprocessor is not required but, if fitted, will allow images to be created several times more quickly. All operations can be performed using the keyboard, although using a mouse is easier for many operations. Calculations can be performed more accurately and more quickly on machines fitted with a 386sx processor or better, but the program is still compatable with older machines. Improved image quality is available with super VGA graphics cards offering 256 colours from a palette of 262144. Provision will be made for the new cards allowing 32768 colours on the screen at once as soon as I can get hold of the technical specifications of such a card. Due to the large size of the program, and the fact that the computer only stores part of it in memory at once, CAL is best used running from a hard drive. If this is not possible, but around 2MB of expanded or extended memory is available, install the RAMDRIVE.SYS utility supplied with DOS (see DOS reference guides) and run CAL from the ramdrive. CAL can use expanded memory for storing pieces of the code, resulting in slight improvements in execution speed. CAL does not require, nor does it use, extended memory. Recent additions to CAL: 1. CAL now features routines to use high-resolution 256 colour super VGA (SVGA) cards. This gives increases in performance and allows CAL to be used on a wider range of machines. Where possible to graphics algorithms are written in assembly language to improve execution times as much as possible. 2. CAL now automatically detects if a 386 processor (or better) is being used and will use an improved integer arithmetic algorithm if possible. 3. Recently added fractal types: - Lorenz attractor - Bifuraction diagram - Composite images (this allows options such as loading a saved image in the form of a sphere or 3D landscape) - Julia set (select Mandelbrot set and then Choose Julia Set from the Fractal menu) - Ushiki's phoenix and associated Julia-type sets - Lyapunov space image - Gumowski and Mira attractor - Symmetrical attractors - Equation solving with Newton's method A total of 16 fractals are now available from CAL - and the user defined formula option can be used to create many more. A wide range of demonstration formulae are provided. 4. A data compression algorithm is used for saving images, which means that less disk space is usually required for keeping a collection of pictures. Additionally a new option - save details only - has been added which stores only the imformation needed to recreate the fractal (typically around 1K) rather than the complete image. A set of seven example images are provided in this form. For details on these fractals, and any others that are available, select the Current fractal types option from the Welcome to CAL! help screen. This is available by pressing F1 as soon as CAL has loaded. 5. A batch drawing mode has been added which will scan the disk for any unfinished images and complete them. This can be used overnight, or when the computer is not going to be used for a while, to finish off any images that there was not time to complete in one go. 6. The VGA and super VGA palette editor has been re-written, allowing for better mouse support and a more user-friendly interface. Colours can be set individually, or a blended range of colours can be created fading from one colour into the next. An introduction to CAL: 1. As an introduction press Return as soon as CAL has loaded to draw the default image. If your copy of the CAL files is the same as the set that I distribute this should be the Mandelbrot set in the 256 colour 320x200 mode that is now supported on most computers. If your machine will not use this mode then read the steps below about configuring the program. 2. Selecting the graphics resolution... All video cards allow for a variety of types of display. On earlier models this may be a choice between a low resolution (i.e. blocky) image with several colours or a less blocky image in black and white. Later systems have been capable of 16 colours and most new graphics cards are capable of displaying 256 colours on the screen at once. The type of resolution and number of colours to use are chosen from the `Display mode' option in the `Configurations' menu. Menu choices are made using the cursor keys to change the highlighted option and return to select it. If you are using a monochrome display and find the text lacks contrast then run cal by typing `CAL /M' which will cause a black and white palette to be used in text modes. Full colours will still be available (if your display supports them) when drawing an image. There are four different types of graphics mode, each progressively more advanced than the one before: CGA - one of the original graphics standards and only really included for machines which do not support more modern displays or to provide a quick overview of a detailed image. At best you can have four colours on the screen and the image does appear very blocky. However, CGA modes are present on almost all computers, including older portable machines. EGA - EGA allows sixteen colours to be used, although you do not have control over them to the same degree as is present with later standards. The resolution is also better - meaning that curves appear less blocky and images are more detailed. VGA - VGA appears to the user as an extension to EGA which allows you to use even higher resolution and to choose the colours that are used from a palette of colours available from the graphics card. SVGA - Super VGA is present on most new machines and allows images to be produced using 256 colours, allowing for such effects as gradual shifts from one colour to another. The resolution available in SVGA means that you can see a lot of detail in images but the extra calculations needed to calculate this detail can slow down drawing. If you are using SVGA modes you must tell CAL which make of graphics card is inside the computer (see next section). 3. Configuring the graphics card... It is necessary to set options about which type of graphics card you are using before any images may be created in a super VGA display mode. You can change the settings at any time you want since all the configuration options are contained within the CAL program itself. The type of graphics card is chosen in the `SVGA Card Type' option in the `Options' menu. You should be presented with a list of about fourteen different types of display card. If the one that you have fitted is listed there (this is often shown immediately upon powering up the computer) then select that option and it will be stored in the configurations file. Note that there are differences between graphics cards by the same manufacturer (e.g. some Tseng cards work in different ways to others, even though the image on the screen appears the same), so it may be necessary to try each of the variations of the card listed. If you cannot find your card listed, or do not know what type of card is fitted to the machine, then try each one in turn until you get successful results. It is best to have a moderate resolution SVGA mode selected during these tests (e.g. 640x480 with 256 colours) since the better standardisation between manufacturers means that non-SVGA modes will work with any graphics card. During configuration you may sometimes get a disjointed image. This is caused by the similar - although not quite identical - methods of accessing the graphics display employed by some manufacturers. Another of the SVGA card types will probably give the correct image. 4. The current fractal type to draw (e.g. Henon attractor, Mandelbrot set etc...) is chosen from the `Select fractal' option in the `Fractal' menu. Use the up and down cursor keys so that the arrow points at the fractal that you would like to draw and press the return key. 5. Further details about using CAL are available using the context sensitive help facilities. Press F1 at any time during the program and use the cursor keys to highlight the topic on which you would like more information before pressing return. The escape key will cancel the help mode. Should you encounter any difficulties with CAL, if you have suggestions for improvements, new fractal algorithms you would like included in future versions or queries of any kind then do not hesitate to contact me. Demonstration images: Since complete images can be very large, demonstration pictures have been stored in a compressed for so that only the bare minimum of data is kept. To see the demonstration images, change to the directory in which CAL resides and start CAL. Choose Batch Mode from the Load/Save menu and select Start. The images will be automatically drawn and saved. The Load option can then be used to load them again. It is probably best to ensure CAL is correctly configured for your graphics card before doing this - see above - because the demonstration images were designed to look best in a 800x600 256 colour mode. If this mode is not available then select the best possible resolution with the largest number of colours from the Display option in the Options menu. The demonstration images are called DEMO1.CGF, DEMO2.CGF etc... Copies of CAL on larger capacity disks (360K upwards) may have additional images, which are already complete, supplied with them. These include examples of the Lyapunov fractal (this is very impressive, but can be slow to calculate without a co-processor) and composite image option. The latter shows the facilities for creating 3D-landscapes and moulding images onto a sphere. Timothy Harris