Author: HP
  Subj: Supported Ram Entry Access
  Date: 07 Oct 1993


1.  Purpose

The purpose of this document is to explain how to get the RAM address
of some of the formerly supported HP48S/SX RAM entry points in a way
that will work for any version of the HP48S/SX/G/GX.  It assumes you
already know how to properly and safely use the entries.

Some entries are accessible only in assembly language, some only in
system RPL, and some in both.

This material is transferred free of charge, as is. Hewlett-Packard
makes no warranty, expressed or implied as to its performance.
Hewlett-Packard specifically disclaims the implied warranties of
merchantability and fitness for any particular purpose.
Hewlett-Packard shall not be liable for any direct, indirect, special,
incidental or consequential damages, whether based on contract, tort,
or any other legal theory. Hewlett-Packard specifically will not offer
any support concerning this material and grants no exclusivity for its
use.  Hewlett-Packard specifically does not offer this material as a
product and does not commit to make this material available in the
future as such.


2.  Display Entries

VDISP2	A 5 nibble pointer to the menu grob.

	System RPL: Use HARDBUFF2 which requires no input and returns
	a pointer to VDISP2 to the stack.

	Assembly: Read the new supported ROM location (addrVDISP2)+2
	to get the RAM address. Example:

		D1=(5)	(=addrVDISP2)+2
		A=DAT1	A
		D1=A			D1 -> VDISP2


VDISP	A 5 nibble updateable pointer to the grob currently being
	displayed.

	System RPL: Use HARDBUFF which requires no input and returns a
	pointer to the stack.

	Assembly: Read the new supported ROM location (addrVDISP)+2 to
	get the RAM address. Example:

		D1=(5)	(=addrVDISP)+2
		C=DAT1	A
		D1=C			D1 -> VDISP


ADISP	A 5 nibble pointer to the "stack" grob.

	System RPL: use ABUFF which requires no input and returns a
	pointer to the stack.

	Assembly: Read the ROM location (addrADISP)+2 to get the RAM
	address. Example:

		D1=(5)	(=addrADISP)+2
		C=DAT1	A
		D1=C			D1 -> ADISP




3.  Keyboard Entries

DISABLE_KBD
	A 1 nibble location which disables keys when non-zero.

	Assembly: Read the new supported ROM location (adrDISABLE_K)+2
	to get the RAM address. Example:

		D0=(5)	(=adrDISABLE_K)+2
		C=DAT0	A
		D0=C			D0 -> DISABLE_KBD


KEYBUFFER
	A 34 nibble RAM location, used to buffer keycodes.

	System RPL: Use GETTOUCH or REPKEY? to get key information.

	Assembly: Read new supported ROM location (adrKEYBUFFER)+2 to
	get RAM address. Example:

		D1=(5)	(=adrKEYBUFFER)+2
		A=DAT1	A
		D1=A			D1 -> KEYBUFFER



KEYSTATE
	A 13 nibble location holding the keyboard state.

	Assembly: Read the new supported ROM location (addrKEYSTATE)+2
	to get the low 4 nibbles of the RAM address. Follow the
	example below to get all 5 nibbles:

		D1=(5)	(=addrKEYSTATE)+2
		A=DAT1	A
		D1=(5)	(=IRAM@)-4
		C=DAT1	A
		D1=C		Set the high nibble of D1
		D1=AS		D1 -> KEYSTATE



LINECOUNTg
	A 2 nibble location holding a copy of the last value written
	to the hardware LINECOUNT register.

	Assembly: Read new supported ROM location (addrLINECNTg)+2 to
	get RAM address. Example:

		D0=(5)	(=addrLINECNTg)+2
		A=DAT0	A
		D0=A			D0 -> LINECOUNTg


ORghost
	A 3 nibble location to keep a copy of the last value written
	to the hardware OR register.

	Assembly: Read new supported ROM location (addrORghost)+2 to
	get the RAM address. Example:

		D0=(5)	(=addrORghost)+2
		C=DAT0	A
		D0=C			D0 -> ORghost



4.  Flag Entries

SystemFlags
	Only RPL access of system flags will work across all versions.
	Use SetSysFlag, ClrSysFlag, and TestSysFlag.


UserFlags
	Only RPL access of system flags will work across all versions.
	Use SetUserFlag, ClrUserFlag, and TestUserFlag.



5.  Miscellaneous Entries

ATTNFLG
	A 5 nibble location holding the ATTN flag.

	System RPL: Use ATTNFLGCLR, ATTNFLG@, ATTN?

	Assembly: Read the new supported ROM location (addrATTNFLG)+2
	to get the RAM address.  Example:

		D0=(5)	(=addrATTNFLG)+2
		A=DAT0	A
		D0=A			D0 -> ATTNFLG


ClkOnNib
	A 1 nibble location.  Nonzero contents ==> ticking clock.

	Assembly: Read new supported ROM location (addrClkOnNib)+2 to
	get the RAM address. Example:

		D1=(5)	(=addrClkOnNib)+2
		C=DAT1	A
		D1=C			D1 -> ClkOnNib


GraphPrtHook
	An 11 nibble location for a graphics print driver hook.

	Assembly: Read the supported ROM location (adrGraphPrtH)+2 to
	get the address of GraphPrtHook. Example:

		D1=(5)	(=adrGraphPrtH)+2
		A=DAT1	A	A[A] ->  GraphPrtHook
		D1=A		D1 -> GraphPrtHook


DSKTOP	A 5 nibble updateable pointer to the top pointer on the data
	stack.

	Assembly: Use the supported routines D1=DSKTOP and D0=DSKTOP.


TEMPENV
	A 5 nibble updateable pointer to temporary environments.

	Assembly: Read the new supported ROM location (addrTEMPENV)+2
	to get the RAM address.  Example:

		D0=(5)	(=addrTEMPENV)+2
		C=DAT0	A
		D0=C			D0 -> TEMPENV


TEMPTOP
	A 5 nibble updateable pointer to the top of TEMPOB.

	Assembly: Read the new supported ROM location (addrTEMPTOP)+2
	to get the RAM address.  Example:

		D1=(5)	(=addrTEMPTOP)+2
		C=DAT1	A
		D1=C			D1 -> TEMPTOP


TIMEOUTCLK
	A 1 nibble location which enables timeout when clear.

	Assembly: Read ROM location (adrTIMEOUTCLK)+2 to get the RAM
	address. Example:

		D1=(5)	(=adrTIMEOUTCLK)+2
		A=DAT1	A
		D1=A			D1 -> TIMEOUTCLK



uart_handshk
	A 1 nibble location holding XON/XOFF handshaking information.

	Assembly: Read new supported ROM location (adr_uart_hand)+2 to
	get RAM address. Example:

		D0=(5)	(=adr_uart_hand)+2
		A=DAT0	A
		D0=A			D0 -> uart_handshk



6.  Actual Addresses

	addrADISP	1265A
	addrATTNFLG	4226A
	addrClkOnNib	0E7D3
	addrKEYSTATE	00D48
	addrLINECNTg	136AC
	addrORghost	0188D
	addrTEMPENV	04E66
	addrTEMPTOP	179E8
	addrVDISP	1263A
	addrVDISP2	1264A
	adrDISABLE_K	047CF
	adrGraphPrtH	32CB6
	adrKEYBUFFER	047DD
	adrTIMEOUTCL	42284
	adr_uart_han	312DA


-----
Note from Mika Heiskanen:

Note that all the entries listed are addresses of the
data loading commands, not the addresses of the data
itself. All but addrKEYSTATE are loaded either with
Dn=(5) or LC(5) so the entries should be used like:

	Dn=(5)	(addrFUBAR)+2
	r=DATn	A

[The command at addrKEYSTATE is D1=(4) =KEYSTATE]

--->	Mika Heiskanen, mheiskan@delta.hut.fi

-----
Another note from Mika:

TestSysFlag etc all use a common ml subroutine that
fetches the location of the flag and the mask to operate
with. The subroutine is at the same address in revs E and
M, but I don't have a chance to check other revs.

For example the following could be used:

=GetFlagA	EQU #537BE *

Input:	A[A] = flag number	Output: D0 = ->flag_nibble
	ST0  = UserFlag?		C.XS = flag_nibble
					A.XS = mask
					R0[A] = saved D0

To set a
user flag:	  | To clear..		| To test..
------------------|---------------------|------------------
ST=1	0	  | ST=1    0		| ST=1	  0
GOSBVL	=GetFlagA | GOSBVL  =GetFlagA	| GOSBVL  =GetFlagA
C=C!A	XS	  | A=-A-1  XS		| C=C&A   XS
DAT0=C	XS	  | C=C&A   XS		| ?C#0	  XS
		  | DAT0=C  XS		| GOYES   tstok
					| tstok [...]

And if above is not somehow feasible then there's the
following code that also is fixed in rev E and rev M.

1C637		=RCLSYSF
1C637 C36C1	CON(5)	(*)+5
1C63C 8FB9760	GOSBVL	=SAVPTR
1C643 1B5C607	D0=(5)	=SystemFlags	* addrSystemFlags ?
1C64A 6610	GOTO	L_1C661
1C64E		=RCLUSERF
1C64E 356C1	CON(5)	(*)+5
1C653 8FB9760	GOSBVL	=SAVPTR
1C65A 1B5D607	D0=(5)	=UserFlags	* addrUserFlags ?
1C661		L_1C661
1C661 1527	A=DAT0	W
1C665 2F	P=	15
1C667 8FC2245	GOSBVL	=PUSHhxs
1C66E 142	A=DAT0	A
1C671 164	D0=D0+	5
1C674 808C	PC=(A)

--->	 Mika Heiskanen, mheiskan@delta.hut.fi