las@apr.UUCP (Larry Shurr) (06/03/86)
Would you like to be able to execute the PC-DOS version of Turbo Pascal
on your Texas Instruments Professional Computer rather than the generic
MS-DOS version? Let me tell you why the answer is yes.
* Faster screen output
* Support for function keys
- but more importantly -
* You can order the PC-DOS versions from the mail-order
discounters much more cheaply than from Borland
I have determined how to do this adaptation. You will need to use the
TI-supplied program, EMULATE.COM and and you must apply the following
patches to the TURBO.COM program image. Please note: This patch set
only gets Turbo Pascal up and running. Most of the special IBM PC
support features such as sound and graphics still do not work. If there
is sufficient interest, I MAY work on additional patches to get these
to work (I would like to see these features working, myself. If you
come up with any such patches, please send them to me and I will com-
bine them with any new patches I come up with to produce an updated
patch set.
Now, assuming your answer is yes, here's what you want to know. But
first, a disclaimer:
I have tested the following patches and I believe
that they work as stated. However, when you patch
your copy of Turbo Pascal, you do so at your own
discretion and at your own risk. Neither I, my
employer, or anyone else warrant these modifica-
tions in any way; nor will I or anyone else
indemnify you against the consequences of employing
them.
Now, enough legal stuff, on with the info:
Required:
* MS-DOS 2.11 or later for the TI Pro
* PC-DOS version 3.01A of Turbo Pascal
What to do:
You must use the EMULATE.COM program supplied on the MS-DOS release disk.
When executed, this program installs itself as a resident program and
emulates a number of the IBM PC ROM BIOS functions. This program will
translate Turbo Pascal's BIOS calls to the appropriate TI Pro calls.
This is how the keyboard and screen I/O are supported. For your con-
venience, edit your AUTOEXEC.BAT file to execute EMULATE.COM. If you
fail to install EMULATE.COM and you attempt to run TURBO.COM, even with
the patches, you will be rewarded with a 1042 system error (wild inter-
rupt) and you will have to reboot.
In addition, the patches described below are required. These changes are
for the "plain" version of Turbo Pascal. They may be applicable to the
8087 and BCD versions as well. If the affected code is in a different
place, however, the patches will have to be adapted. I'm not in a
position to determine that right now, sorry.
The affected code is in two areas: One is a rather funky segment of code
which apparently estimates the system clock speed by intercepting the real-
time clock interrupt and flipping a flag while a loop spins waiting for the
the state of that flag to change. On the TI Pro, the measure will be too
fast, due to its 25 millisecond clock interval (instead of the IBM PC' 55
milliseconds). I do not yet know what this estimate is used for (I suspect
it has to do with the sound feature) and I have done nothing to correct the
error in the estimate. The other change is in a routine used by the Turbo
Pascal editor to write to the display. The Turbo editor is "poorly behaved"
and writes directly to video memory. I have patched this code to write to
the TI Pro's video memory. Since the TI display hardware is significantly
different from the IBM PC, the result is itself rather funky, but effective.
Differences between the IBM PC version
of TURBO.COM and the patched version
for the TI Pro:
Offset Original New
in File data for data for
TURBO.COM IBM PC TI Pro
-------- ------ ------
000000A6 20 0C
000000A7 00 01
000000CC 20 0C
000000CD 00 01
00005092 16 2D
00005097 8B B4
00005098 FD 17
00005099 8E CD
0000509A 06 49
0000509B 90 D1
0000509C 05 ED
0000509D BE 03
0000509E EE EA
0000509F 04 B8
000050A0 80 00
000050A1 3E DE
000050A2 93 8E
000050A3 05 C0
000050A4 FF 8B
000050A5 74 FD
000050A6 03 BE
000050A7 F3 EE
000050A8 A5 04
000050A9 C3 AD
000050AA BA 82
000050AB DA FC
000050AC 03 07
000050AD AD 75
000050AE 8B 02
000050AF E8 B4
000050B0 EC 0D
000050B1 D0 26
000050B2 D8 88
000050B3 72 26
000050B4 FB 00
000050B5 FA 18
000050B6 EC AA
000050B7 D0 E2
000050B8 D8 F0
000050B9 73 26
000050BA FB C6
000050BB 95 06
000050BC AB 00
000050BD FB 18
000050BE E2 0F
000050BF ED 90
Following is a disassembly listing of the affected code for the IBM PC
version of TURBO Pascal. The "xxxx"'s in the listing represent the
fact that the segment portion of the address is dependent on your
system configuration. The segment base for the program is irrelevant
for purpose of this discussion anyway.
Code for IBM PClone
xxxx:01A0 C606940100 MOV B,[0194],00
xxxx:01A5 BE2000 MOV SI,0020
xxxx:01A8 26:8B04 MOV AX,ES:[SI]
xxxx:01AB 2E:A39501 MOV CS:[0195],AX
xxxx:01AF 26:8B4402 MOV AX,ES:[SI+0002]
xxxx:01B3 2E:A39701 MOV CS:[0197],AX
xxxx:01B7 FA CLI
xxxx:01B8 26:C704C401 MOV W,ES:[SI],01C4
xxxx:01BD 26:8C4C02 MOV ES:[SI+0002],CS
xxxx:01C1 FB STI
xxxx:01C2 EB22 JMPS 01E6
xxxx:01C4 1E PUSH DS
xxxx:01C5 50 PUSH AX
xxxx:01C6 33C0 XOR AX,AX
xxxx:01C8 8ED8 MOV DS,AX
xxxx:01CA C7062000DB01 MOV W,[0020],01DB
xxxx:01D0 2E:A39201 MOV CS:[0192],AX
xxxx:01D4 58 POP AX
xxxx:01D5 1F POP DS
xxxx:01D6 2E:FF2E9501 JMP F,CS:[0195]
xxxx:01DB 2E:C6069401FF MOV B,CS:[0194],FF
xxxx:01E1 2E:FF2E9501 JMP F,CS:[0195]
xxxx:5191 7416 JZ 51A9
xxxx:5193 8BCE MOV CX,SI
xxxx:5195 D1E9 SHR CX,1
xxxx:5197 8BFD MOV DI,BP
xxxx:5199 8E069005 MOV ES,[0590]
xxxx:519D BEEE04 MOV SI,04EE
xxxx:51A0 803E9305FF CMP B,[0593],FF
xxxx:51A5 7403 JZ 51AA
xxxx:51A7 F3/A5 REP MOVSW
xxxx:51A9 C3 RET
xxxx:51AA BADA03 MOV DX,03DA
xxxx:51AD AD LODSW
xxxx:51AE 8BE8 MOV BP,AX
xxxx:51B0 EC IN AL,DX
xxxx:51B1 D0D8 RCR AL,1
xxxx:51B3 72FB JC 51B0
xxxx:51B5 FA CLI
xxxx:51B6 EC IN AL,DX
xxxx:51B7 D0D8 RCR AL,1
xxxx:51B9 73FB JNC 51B6
xxxx:51BB 95 XCHG AX,BP
xxxx:51BC AB STOSW
xxxx:51BD FB STI
xxxx:51BE E2ED LOOP 51AD
xxxx:51C0 C3 RET
Similarly, the following is a disassembly listing of the code as
modified for the TI Pro with the changed code marked for easy
reference.
Code for TI Professional
( "<---" indicates new code )
xxxx:01A0 C606940100 MOV B,[0194],00
xxxx:01A5 BE0C01 MOV SI,010C <---
xxxx:01A8 26:8B04 MOV AX,ES:[SI]
xxxx:01AB 2E:A39501 MOV CS:[0195],AX
xxxx:01AF 26:8B4402 MOV AX,ES:[SI+0002]
xxxx:01B3 2E:A39701 MOV CS:[0197],AX
xxxx:01B7 FA CLI
xxxx:01B8 26:C704C401 MOV W,ES:[SI],01C4
xxxx:01BD 26:8C4C02 MOV ES:[SI+0002],CS
xxxx:01C1 FB STI
xxxx:01C2 EB22 JMPS 01E6
xxxx:01C4 1E PUSH DS
xxxx:01C5 50 PUSH AX
xxxx:01C6 33C0 XOR AX,AX
xxxx:01C8 8ED8 MOV DS,AX
xxxx:01CA C7060C01DB01 MOV W,[010C],01DB <---
xxxx:01D0 2E:A39201 MOV CS:[0192],AX
xxxx:01D4 58 POP AX
xxxx:01D5 1F POP DS
xxxx:01D6 2E:FF2E9501 JMP F,CS:[0195]
xxxx:01DB 2E:C6069401FF MOV B,CS:[0194],FF
xxxx:01E1 2E:FF2E9501 JMP F,CS:[0195]
xxxx:5191 742D JZ 51C0 <---
xxxx:5193 8BCE MOV CX,SI
xxxx:5195 D1E9 SHR CX,1
xxxx:5197 B417 MOV AH,17 <---
xxxx:5199 CD49 INT 49 <---
xxxx:519B D1ED SHR BP,1 <---
xxxx:519D 03EA ADD BP,DX <---
xxxx:519F B800DE MOV AX,DE00 <---
xxxx:51A2 8EC0 MOV ES,AX <---
xxxx:51A4 8BFD MOV DI,BP <---
xxxx:51A6 BEEE04 MOV SI,04EE <---
xxxx:51A9 AD LODSW <---
xxxx:51AA 82FC07 CMP AH,07 <---
xxxx:51AD 7502 JNZ 51B1 <---
xxxx:51AF B40D MOV AH,0D <---
xxxx:51B1 26:88260018 MOV ES:[1800],AH <---
xxxx:51B6 AA STOSB <---
xxxx:51B7 E2F0 LOOP 51A9 <---
xxxx:51B9 26:C60600180F MOV B,ES:[1800],0F <---
xxxx:51BF 90 NOP <---
xxxx:51C0 C3 RET
Commands for modifying TURBO.COM
You may modify TURBO.COM using the MS-DOS DEBUG program. Assume that
you have a copy of TURBO.COM in drive A: and that you have selected
A: as your default drive. Enter the following seuquence of commands
to modify it for the TI Professional Computer. Note: perform these
modifications on a copy of your turbo disk, not your original.
A>debug turbo.com
-a1a5
xxxx:01A5 MOV SI,010C
xxxx:01A8
-a1ca
xxxx:01CA MOV W,[010C],01DB
xxxx:01D0
-a5191
xxxx:5191 JZ 51C0
xxxx:5193 MOV CX,SI
xxxx:5195 SHR CX,1
xxxx:5197 MOV AH,17
xxxx:5199 INT 49
xxxx:519B SHR BP,1
xxxx:519D ADD BP,DX
xxxx:519F MOV AX,DE00
xxxx:51A2 MOV ES,AX
xxxx:51A4 MOV DI,BP
xxxx:51A6 MOV SI,04EE
xxxx:51A9 LODSW
xxxx:51AA CMP AH,07
xxxx:51AD JNZ 51B1
xxxx:51AF MOV AH,0D
xxxx:51B1 MOV ES:[1800],AH
xxxx:51B6 STOSB
xxxx:51B7 LOOP 51A9
xxxx:51B9 MOV B,ES:[1800],0F
xxxx:51BF NOP
xxxx:51C0 RET
-w
-q
A>
You will now have a TI Pro version. When you run this program on a
TI Pro on which you have installed EMULATE.COM, you will now be able
to use Turbo Pascal.
Hope this information increases your computing pleasure.
Regards,
Larry
--
------------------------------------------------------------------------------
BRITANNUS (shocked): Caesar, this is not proper.
THEODOTUS (outraged): How?
CAESAR (recovering his self-possession):
Pardon him Theodotus: he is a barbarian, and thinks that
the customs of his tribe and island are the laws of nature.
(_Caesar and Cleopatra_, Act II - G. B. Shaw)
Larry A. Shurr (osu-eddie!apr!las || 137c South Towne Ln; Delaware, OH 43015)