The GROOT.ROM list of changes.
Henk de Groot
spectrum. Here is what I have done to the original ZX-Spectrum rom.
Featues:
o Bug fixes as mentioned in "The complete Spectrum Rom Disassembly" by
Dr Ian Logan and Dr Frank O'Hara.
o Support for EPSON printer via an Z80-PIO chip and centronics connection.
o Monitor support: start up with black screen with white characters.
o Lightpen support: Lightpen routine for DK'Tronics lightpen build in.
Here is the assembly code of the changes. The whole thing can be found on
archive sites under the name "newrom.???" where ??? is .exe, .zip, .arj or
whatever.
------------------------- BEGIN OF CHANGE LIST ---------------------------------
This file relects the changes to the original ZX Spectrum ROM. The labels and
page numbers refer to the book "The Complete Spectrum Rom Disassembly" by
Dr Ian Logan & Dr Frank O'Hara, published by Melbourne House Publishers,
ISBN 0 86161 116 0.
Jump to initialize the Z80-PIO chip
--------------------------------------------------------------------------------
THE 'START'
The maskable interrupt is disabled and the DE register pair set to hold the 'top
of possible RAM'
0000 F3 START DI Disable the 'keyboard interrupt'
0001 AF XOR A +00 for 'start' (but +FF for
'NEW').
0002 11FFFF LD DE,FFFF Top of possible RAM.
0005 C3AA04 JP 04AA,PIO-INIT Init Z80-PIO
--------------------------------------------------------------------------------
New NMI routine: Quick start basic without memory erase!
--------------------------------------------------------------------------------
0066 F3 RESET DI Disable the 'keyboard interrupt'
0067 AF XOR A Make the border black in
0068 D3FE OUT (FE),A color.
006A 3E3F LD A,3F Set I register to hold
006C ED47 LD I,A the value of +3F.
006E 2AB25C LD HL,(RAMTOP) Preserve current RAMTOP
0071 C31912 JP 1219,RAM-SET Act as if RAM is tested
--------------------------------------------------------------------------------
Initialize Z80-PIO. This is a new routine. This routine is stored at a spot
where useless ZX81 code was left, called "THE 'PROGRAM NAME' SUBROUTINE (ZX81)"
--------------------------------------------------------------------------------
Init Z80-PIO
Port DB = Control port "A"
Port FB = Control port "B"
Port 9B = Data port "A"
Port BB = Data port "B"
04AA 3E3F PIO-INIT LD A,3F Program Z80-PIO port A to
04AC D3DB OUT (DB),A be all "outputs".
04AE 3EFF LD A,FF Port A will be connected to the
04B0 D3FB OUT (FB),A Centronix data lines.
04B2 3E80 LD A,80 Program port B to "inputs"
04B4 D3FB OUT (FB),A Except bit 8 on port B
04B6 3E02 LD A,02 Bit 2 of port B will be the
04B8 D3BB OUT (BB),A "Stobe", initialize to "1"
04BA AF XOR A +00 for 'start' (but +FF for
'NEW').
04BB C3CB11 JP 11CB,START/NEW Jump forward.
--------------------------------------------------------------------------------
Printer support for EPSON type printer added.
--------------------------------------------------------------------------------
09F4 C32C39 PRINT-OUT JP 392C,PRINTER Call printer routine
--------------------------------------------------------------------------------
Fix bug on page 33, LD A,+18 sould read LD A,+19
--------------------------------------------------------------------------------
0A30 0E02 LD C,02 Set column value
0A32 3E19 LD A,19 Test against top line
0A34 B8 CP B Note: Bug fixed, was 18
--------------------------------------------------------------------------------
Fix bug on page 34, exit via PO-STORE
--------------------------------------------------------------------------------
0A4A F1 POP AF Fetch old value of P-FLAG
0A4B C32039 JP 3920,REP-PO-ST Jump to repair routine
--------------------------------------------------------------------------------
Change for printer implementation
--------------------------------------------------------------------------------
THE 'COPY-LINE' SUBROUTINE
The subroutine is entered with HL register pair holding the base address of the
thirtytwo bytes that form the pixel-line and the B register holding the
pixel-line number.
0EF4 C36E38 COPY-LINE JP 386E,COPY-LN Copy printerbuffer to printer
--------------------------------------------------------------------------------
Turn initial white screen into initial black. This is a lot better when using
a monitor on the spectrum.
--------------------------------------------------------------------------------
11CB 47 START/NEW LD B,A Save the flag for later.
11CC 3E00 LD A,00 Makes the border black in
11CE D3FE OUT (FE),A colour (was white).
--------------------------------------------------------------------------------
Turn initial white screen into initial black. This is a lot better when using
a monitor on the spectrum.
--------------------------------------------------------------------------------
1265 3E07 LD A,07 Initialise the colour system
1267 328D5C LD (ATTR-P),A variables to : FLASH 0,
126A 328F5C LD (ATTR-T),A BRIGHT 0, PAPER 0,& INK 7
126D 32485C LD (BORDCR),A
--------------------------------------------------------------------------------
New Copyright message:
--------------------------------------------------------------------------------
Was:
1539 '(C) 1982 Sinclair Research Ltd'
New:
1539 '(C) New Zx Spectrum ROM READY '
--------------------------------------------------------------------------------
Fix bug on page 177, -65536 bug
--------------------------------------------------------------------------------
3032 C3393A JP 3A39,FIX-177 Jump to fix for -65536
3035 23 NOFIX-177 INC HL Point to the next location
3036 72 LD (HL),D Store the high byte of the
result.
3037 2B DEC HL Move the pointer back to
3038 2B DEC HL address the first byte of the
3039 2B DEC HL result.
303A D1 FIXED-177 POP DE Restore STKEND to DE.
303B C9 RET Finished.
--------------------------------------------------------------------------------
Fix bug on page 185, Jump was to the wrong place
--------------------------------------------------------------------------------
31FF 28DA JR Z,31DB,DIV-34TH Was: jump to DIV-START
--------------------------------------------------------------------------------
Fix bug on page 186, Code sould be skipped
--------------------------------------------------------------------------------
3221 FE91 CP 91 Compare e to 91 hex, 145
decimal.
3223 181A JR 323F,T-SMALL Jump always, omitting the code
from 3225 to 323E always!
--------------------------------------------------------------------------------
New COPY-LINE routine, copy to EPSON printer via Z80-PIO
--------------------------------------------------------------------------------
386E DDE5 COPY-LN PUSH IX Use IX as an index
3870 3A815C LD A,(PR-CC) Get printer column
3873 0605 COPY-MUL LD B,05 Multiply 2^5 (=32) times
3875 87 ADD A to calculate offset in the
3876 10FD DJNZ COPY-MUL printer buffer.
3878 1600 LD D,00 Transfer the offset to the
387A 5F LD E,A DE register pair
387B DD21005B LD IX,5B00 Load IX with printer buffer
387F 5F LD E,A Why again??
3880 DD19 ADD IX,DE Add the offset to IX register
3882 0620 LD B,20 Fetch 32 bytes
3884 7E LD A,(HL) And store into the printer
3885 DD7700 LD (IX+00),A Buffer.
3888 23 INC HL Next byte to be printed
3889 DD23 INC IX Next byte in the printer buffer.
388B 10F7 DJNZ 3884 Until all 32 bytes are done.
388D 3A815C LD A,(PR-CC) Increment column number.
3890 3C INC A
3891 FE08 CP 08 Do we have 8 lines in the buffer
3893 2806 JR Z,COPY-PRT Yes, jump forward
3895 32815C LD (PR-CC),A Store the new column number
3898 DDE1 POP IX Restore IY register
389A C9 RET End of copy-ln routine.
COPY-PRT
Copy the contents of the printerbuffer at 5B00 hex to an EPSON like
printer.
389B F5 COPY-PRT PUSH AF Don't distroy register A
389C 21005B LD HL,5B00 HL points to the printer buffer
389F 3E1B LD A,1B Send "1B 41 08"
38A1 CD0A39 CALL 390A,PRT-BYTE (set linefeet pitch to
38A4 3E41 LD A,41 8/72 inch)
38A6 CD0A39 CALL 390A
38A9 3E08 LD A,08
38AB CD0A39 CALL 390A,PRT-BYTE
38AE 3E1B LD A,1B Send "1B 4D"
38B0 CD0A39 CALL 390A,PRT-BYTE (Select Elite (12 cpi))
38B3 3E4D LD A,4D
38B5 CD0A39 CALL 390A,PRT-BYTE
38B8 3E1B LD A,1B Send "1B 4B 00 01"
38BA CD0A39 CALL 390A,PRT-BYTE (Print standard density
38BD 3E4B LD A,4B graphics, 256 dots will
38BF CD0A39 CALL 390A,PRT-BYTE follow)
38C2 3E00 LD A,00
38C4 CD0A39 CALL 390A,PRT-BYTE
38C7 3E01 LD A,01
38C9 CD0A39 CALL 390A,PRT-BYTE
Note: the pixels in the buffer are horizontally aligned, the printer head
has the pixels verticaly aligned. We have to fetch one bit from the
the 8 byte that are above eachother.
38CC 0620 LD B,20 Handle 32 bytes.
38CE 112000 LD DE,0020 Offset between succesive
38D1 C5 NXT-BYTE PUSH BC lines.
38D2 0608 LD B,08 There are 8 pixels in one byte
38D4 C5 NXT-PIXEL PUSH BC
38D5 E5 PUSH HL
38D6 0608 LD B,08 We print 8 pixels at the time
38D8 CB16 NXT-FETCH RL (HL) Get one bit from this byte
38DA 17 RLA Shift into register A
38DB 19 ADD HL,DE Handle next byte
38DC 10FA DJNZ 38D8,NXT-FETCH
38DE E1 POP HL
38DF C1 POP BC
38E0 CD0A39 CALL 390A,PRT-BYTE Print out the pixel image in A
38E3 10EF DJNZ 38D4,NXT-PIXEL Next pixel of this set of bytes
38E5 C1 POP BC
38E6 23 INC HL
38E7 10E8 DJNZ 38D1,NXT-BYTE Next group of 8 bytes
38E9 3E0D LD A,0D Send cariage return
38EB CD0A39 CALL 390A,PRT-BYTE
38EE 3E0A LD A,0A Send linefeet
38F0 CD0A39 CALL 390A,PRT-BYTE
38F3 3E1B LD A,1B Send "1B 32"
38F5 CD0A39 CALL 390A,PRT-BYTE (linefeed pitch 1/6 inch)
38F8 3E32 LD A,32
38FA CD0A39 CALL 390A,PRT-BYTE
38FD 3E12 LD A,12 Send DC2 to cancel Elite
38FF CD0A39 CALL 390A,PRT-BYTE
3902 AF XOR A Clear PR-CC.
3903 32815C LD (PR-CC),A
3906 F1 POP AF Restore register A
3907 DDE1 POP IX This one was left on the stack
(this part was "called" by
a jump instruction)
3909 C9 RET End of copy-ln routine.
PRT-BYTE
Send the contents of register A to the printer. The register contents will
not be changed after the routine has been completed.
390A C5 PRT-BYTE PUSH BC Save all the register we need
390B F5 PUSH AF
390C AF XOR A Look if the printer is BUSY
390D DBBB PRT-BUSY IN A,(BB) Look at dataline 8 of Z80-PIO
390F 07 RLCA port B.
3910 38FA JR C,390C,PRT-BUSY Repeat if printer is busy
3912 F1 POP AF
3913 F5 PUSH AF Restore register A
3914 D39B OUT (9B),A Put A on Z80-PIO port A
3916 AF XOR A Make A clean
3917 D3BB OUT (BB),A Lower the STROBE signal, data
3919 3E02 LD A,02 line 2 of port B. Immediately
391B D3BB OUT (BB),A rais it again. The data is
391D F1 POP AF clocked in into the printer
391E C1 POP BC with the STROBE signal.
391F C9 RET Restore registers and return
--------------------------------------------------------------------------------
Fix bug on page 34, exit via PO store.
--------------------------------------------------------------------------------
3920 32915C REP-PO-ST LD (P-FLAG),A This instruction was overwritten
3923 C3DC0A JP 0ADC,PO-STORE Jump to PO-STORE (the Fix)
--------------------------------------------------------------------------------
Junk, I'm sorry!
--------------------------------------------------------------------------------
3926 2A805C LD HL,(5C80)
3929 265B LD H,5B
392B C9 RET
--------------------------------------------------------------------------------
Support for serial printer, called from the print routine at 09F4 in the ROM
--------------------------------------------------------------------------------
392C CD030B PRINTER CALL 0B03,PO-FETCH The current print position
392F FDCB014E BIT 1,(FLAGS) Test if printer, if not continue
3933 CAF709 JP Z,09F7 the original routine PRINT-OUT
3936 CA283A JP Z,3A28,PR-REINIT Looks like a NOP to me...
3939 FE06 CP 06 Test for PRINT comma (,)
393B CAC839 JP Z,39C8,PR-COMMA Handle a comma "TAB"
393E FE0D CP 0D Test for cariage return
3940 2833 JR Z,3975,PR-CR Handle cariage return
3942 FE16 CP 16 Test for AT control character
3944 2854 JR Z,399A,PR-AT Handle AT control
3946 FE17 CP 17 Test for TAB control character
3948 284A JR Z,3994,PR-TAB Handle TAB control
394A FE1C CP 1C Non sinclair extension
394C 2818 JR Z,3966,PR-TRANS Transparent writes!
394E FE20 CP 20 Test for other controlls
3950 DA0A39 JP C,390A,PRT-BYTE Other controls direct to printer
3953 FE80 CP 80 Test for normal ASCII set
3955 382F JR C,3986,PR-NORM Handle normal characters
3957 FE90 CP 90 Test for block graphics
3959 DA0E3A JP C,3A0E,PR-GRAPH Handle block grapics
395C D6A5 SUB A5 Re-base on tokens
395E D2100C JP NC,0C10,PO-TOKENS Expand token
3961 C615 ADD 15 Re-base on UDG's
3963 C3F939 JP 39F9,PR-UDG Handle UDG's
PR-TRANS
Transparent writes. The character following the transparent write control
will be send to the printer unmodified, This allows printout of non sinclair
characters, it creates an access path to all the printers capabilities without
limitation!
3966 116C39 PR-TRANS LD DE,396C Point to PR-TRANS2
3969 C3800A JP 0A80,PO-CHANGE Change output routine entry
396C CD0A39 PR-TRANS2 CALL 390A,PRT-BYTE Send byte unmodified
396F 11F409 LD DE,09F4 Point to PRINT-OUT
3972 C3800A JP 0A80,PO-CHANGE Change output routine entry
PR-CR
Send a linefeet and cariage return to the printer.
3975 FD364500 PR-CR LD (PR-CC),00 Reset the column counter
3979 CD283A CALL 3A28,PR-REINIT Re-initialize the Z80-PIO
397C 3E0A LD A,0A Send a linefeet
397E CD0A39 CALL 390A,PRT-BYTE
3981 3E0D LD A,0D Send a cariage return
3983 C30A39 JP 390A,PRT-BYTE Send and exit via PRT-BYTE
PR-NORM
Printout a normal character.
3986 FE60 PR-NORM CP 60 Check if it's a pound character
3988 2865 JR Z,39EF,PR-POUND It is, special action
398A FE7F CP 7F Check if it's a copyright symbol
398C 2866 JR Z,39F4,PR-CRIGHT It is, special action
398E FD3445 INC (PR-CC) Advancd column pointer
3991 C30A39 JP 390A,PRT-BYTE Send byte and exit.
PR-TAB and PR-AT
The TAB and AT control characters are followed by one or two column and row
characters (for AT only). We bend the input stream temporary to another
routine to pick the characters up. Not that he row information of the AT
control is send to the bitbucket (i.e. is skipped).
3994 11A639 PR-TAB LD DE,39A6 Point to PR-TAB2
3997 C3800A JP 0A80,PO-CHANGE Change output routine entry
399A 11A039 PR-AT LD DE,39A0 Point to PR-AT2
399D C3800A JP 0A80,PO-CHANGE Change output routine entry
39A0 11B439 PR-AT2 LD DE,39B4 Point to PR-AT3
39A3 C3800A JP 0A80,PO-CHANGE Change output routine entry
39A6 11AE39 PR-TAB2 LD DE,39AE Point to PR-TAB3
39A9 CD800A CALL 0A80,PO-CHANGE Change output routine entry
39AC 180C JR 39BA,PR-AT-TAB Now execute TAB instruction
39AE 11F409 PR-TAB3 LD DE,09F4 Point to PRINT-OUT
39B1 C3800A JP 0A80,PO-CHANGE Change output routine entry
39B4 11F409 PR-AT3 LD DE,09F4 Point to PRINT-OUT
39B7 CD800A CALL 0A80,PO-CHANGE Change output routine entry
39BA FD9645 PR-AT-TAB SUB (PR-CC) Test against current position
39BD D8 RET C We already passed the position
39BE C8 RET Z We already are at the position
39BF 47 LD B,A Nr of spaces to print in B
39C0 3E20 PR-SPACE LD A,20 load A with space character
39C2 CD8639 CALL 3986,PR-NORM Printout the space
39C5 10F9 DJNZ 39C0 Repeat until B holds 0
39C7 C9 RET Finished.
PR-COMMA
This control (use in basic to make colums) advances the output to the nearest
column which is a multiple of 16.
39C8 FD7E45 PR-COMMA LD A,(PR-CC) Fetch current position
39CB 47 LD B,A Save in register B
39CC E6F0 AND F0 Calculate A MOD 16
39CE C610 ADD 10 Add 16 (tabs are each 16th pos)
39D0 90 SUB B Calculate nr of spaces to
39D1 47 LD B,A be printed
39D2 18EC JR 39C0,PR-SPACE Print spaces.
39D4 C9 RET Junk
PR-8BYTES
Print character or graphic image of 8x8 pixel format. The image is stored
in MEMBOT. The printer must have been set up to receive the 8 image
bytes.
39D5 0608 PR-8BYTES LD B,08 We have 8 pixels
39D7 C5 PR-8NXTPI PUSH BC Save pixel counter
39D8 0608 LD B,08 We have 8 bytes to handle
39DA 21925C LD HL,MEMBOT Place where the bytes are
39DD AF XOR A Start with clean acumulator
39DE CB16 PR-8NXTBY RL (HL) Fetch a bit from current byte
39E0 CB17 RL A Shift bit into A
39E2 23 INC HL Next byte
39E3 10F9 DJNZ 39DE,PR-8NXTBY Until 8 Bytes are handled
39E5 CD0A39 CALL 390A,PRT-BYTE Print out the image
39E8 C1 POP BC Restore pixel counter
39E9 10EC DJNZ 39D7,PR-8NXTPI Loop until 8 pixels are read
39EB FD3445 INC (PR-CC) Increment coulumn pointer
39EE C9 RET Ready.
PR-POUND
Print out a pound character. A pound character is not available in an
american ASCII set, it is however in a Spectrum. We have to compose the
pound sign ourselfs.
39EF 21003F PR-POUND LD HL,3F00 HL points to pound sign.
39F2 1810 JR 3A04,PR-IMAGE Print character image addressed
by HL.
PR-CRIGHT
Print out a copyright character. A copyright character is not available in an
american ASCII set, it is however in a Spectrum. We have to compose the
copyright sign ourselfs.
39F4 21F83F LD HL,3FF8 HL points to copyright.
39F7 1810 JR 3A04,PR-IMAGE Print character image addressed
by HL.
PR-UDG
Print User defined characters. A holds the number of the UDG to be printer
i.e. A=0 means print UDG "A" = character 144 (90 Hex).
39F9 ED5B7B5C PR-UDG LD DE,(UDG) Load DE with UDG base
39FD 6F LD L,A UDG number to HL
39FE 2600 LD H,00
3A00 29 ADD HL,HL Multiply by 8
3A01 29 ADD HL,HL
3A02 29 ADD HL,HL
3A03 19 ADD HL,DE Add UDG base to HL
PR-IMAGE
Print 8 byte image pointed to by HL to the printer by means of graphics.
3A04 11925C PR-IMAGE LD DE,MEMBOT Temporary storage space
3A07 010800 LD BC,0008 Copy all 8 bytes
3A0A EDB0 LDIR
3A0C 1804 JR 3A12,PR-MEMBOT Print this image and return.
3A0E 47 PR-GRAPH LD B,A Move the graphic code
3A0F CD380B CALL 0B38,PO-GR-1 Construct the graphic form.
PR-MEMBOT
Print 8 byte image stored in MEMBOT.
3A12 3E1B PR-MEMBOT LD A,1B Send "1B 4B 08 00"
3A14 CD0A39 CALL 390A,PRT-BYTE (Print standard density
3A17 3E4B LD A,4B graphics, 8 bytes will
3A19 CD0A39 CALL 390A,PRT-BYTE follow)
3A1C 3E08 LD A,08
3A1E CD0A39 CALL 390A,PRT-BYTE
3A21 3E00 LD A,00
3A23 CD0A39 CALL 390A,PRT-BYTE
3A26 18AD JR 39D5,PR-8BYTES Send the 8 graphic bytes
PR-REINIT
Initialize Z80-PIO. If a program distroyed the programming of the Z80-PIO
this routine will fix it. This routine is called whenever a cariage return
is send to the printer.
3A28 3E3F PR-REINIT LD A,3F
3A2A D3DB OUT (DB),A
3A2C 3EFF LD A,FF
3A2E D3FB OUT (FB),A
3A30 3E80 LD A,80
3A32 D3FB OUT (FB),A
3A34 3E02 LD A,02
3A36 D3BB OUT (BB),A
3A38 C9 RET
--------------------------------------------------------------------------------
Fix bug on page 177, -65536 bug, Implementation partly based on page 230
The implementation of page 230 could be implemented because I want to continue
the original ROM routine at the spot just after the patched in 'JP'instruction.
--------------------------------------------------------------------------------
3A39 F5 FIX-177 PUSH AF Save the sign byte in A.
3A3A 3C INC A Make any FF in A into 00.
3A3B B3 OR E Test all 3 bytes now for zero.
3A3C B2 OR D
3A3D 2014 JR NZ,3A53,ADD-STORE Jump if not -65536.
3A3F F1 POP AF Clear the stack.
3A40 E5 PUSH HL Don't change HL pointer!
3A41 3680 LD (HL),80 Enter 80 hex into second byte.
3A43 23 INC HL
3A44 3600 LD (HL),00 Enter 00 hex into third byte.
3A46 23 INC HL
3A47 3600 LD (HL),00 Enter 00 hex into fourth byte.
3A49 23 INC HL
3A4A 3600 LD (HL),00 Enter 00 hex into fifth byte.
3A4C E1 POP HL
3A4D 2B DEC HL
3A4E 3691 LD (HL),91 Enter 91 hex into first byte.
3A50 C33A30 JP 303A,FIXED-177 Jump to the POP DE instruction
Just before the RET of the
original routine.
3A53 F1 ADD-STORE POP AF
The next instructions are left over because the 'JP' was patched over it
3A54 77 LD (HL),A Store it on the stack
3A55 23 INC HL
3A56 73 LD (HL),E
3A57 C33530 JP 3035,NOFIX-177
--------------------------------------------------------------------------------
Lightpen routine
This routine is not called from other routines in the rom but its meant to
be called from basic. The adress is 15555, so its easy to remember.
The routine is meant for a DK'Tronics lightpen. I have such a pen, but no
schematic diagram.
--------------------------------------------------------------------------------
3CC3 0E3F LIGHT-IN LD C,3F
3CC5 210000 LD HL,0000 Set line counter to 0
3CC8 11FB01 LD DE,01FB Timing loop counter init
3CCB 76 HALT Wait for interrupt
3CCC 1B LI-TIME1 DEC DE Decrement counter
3CCD 7A LD A,D Compare to 0
3CCE B3 OR E
3CCF 20FB JR NZ,3CCC,LI-TIME1 While not 0 loop back
3CD1 110001 LD DE,0100 Timeout timer
3CD4 3EFF LD A,FF For "CP D" below
3CD6 ED40 LI-AGAIN IN B,(C) Read lightpen input port.
3CD8 CB40 BIT 0,B Wait for signal from pen.
3CDA 2809 JR Z,3CE5,LI-FOUND If signal is found jump out
3CDC 060D LD B,0D Timing loop counter init
3CDE 10FE LI-TIME2 DJNZ 3CDE,LI-TIME2 Wait a little
3CE0 23 INC HL Increment Line counter
3CE1 1B DEC DE Decrement timeout counter
3CE2 BA CP D If D becomes FF time-out
3CE3 20F1 JR NZ,3CD6,LI-AGAIN
3CE5 3E00 LI-FOUND LD A,00 Compare against 00
3CE7 BC CP H Are we above the first line?
3CE8 20D9 JR NZ,3CC3,LIGHT-IN Light pen at wrong pos, redo
3CEA CB3D SRL L HL counts faster than there
3CEC CB3D SRL L are rows. Devide by 8 to
3CEE CB3D SRL L get a real line number.
3CF0 E5 PUSH HL Transfer line number to BC
3CF1 C1 POP BC The contents of BC will be the
3CF2 C9 RET Return value of the "USR"
function
--------------------------------------------------------------------------------
Change arrow-up character (on key 'H') to '^' which is more standard in ASCII
sets. It's also used a lot in Pascal (Hisoft Pascal HP4TM16) which uses this
character as a pointer.
--------------------------------------------------------------------------------
3EF2 DEFB 28
3EF3 DEFB 44
3EF4 DEFB 00
3EF5 DEFB 00
3EF6 DEFB 00
--------------------------------------------------------------------------------
-------------------------- END OF CHANGE LIST ----------------------------------
--
/ / de Groot Dep: WGA | E-Mail: gr...@idca.tds.philips.nl
/---/ __ __ / Tel: +31 55 432104 | Corp: Digital Equipment Corporation
/ / (-_ / / /( Loc: V2-B03 | Site: Apeldoorn, The Netherlands