Fix for "Runtime Error 200" bug of Borland Pascal 7 on fast PCs

Also available:

• french translation
• Deutsche Version

Contents:

• Preface
• Cause explained
• Solutions Index
• Comments
• What's new (25-May-1999)
• other Web Pages

Preface

All programs compiled with Borland Pascal 7 that use the system unit Crt (almost all programs do that) abort with the error message "Runtime Error 200" on all fast PCs, for example Pentium II with 233 MHz.

Programs compiled with Borland Pascal 6 are said to not abort with a runtime error, but their delay is completely wrong on fast PCs (and the problem starts there at much lower speeds than the problem of version 7).

This Web page tries to explain the problem and summarize some existing solutions.

Borland (aka Inprise) does not offer a solution for this bug (shame on them!). Instead their Pascal Developer Support recommends an Altavista search, which probably is how you have found this web page.

Cause

The delay initialization counts how often a tiny do-nothing loop must be called in order to delay by 55 milliseconds (time measured by reading the Bios Time Counter at memory address 40:6C that ticks 18.2 times a second, i.e. each 55 milliseconds).

This number is then divided by 55 to get the number of calls for one millisecond. The result is written to a word (16 bit) variable. The overflow of this variable triggers the run time error (the meaning of Runtime Error 200 is division by zero, but it is caused by an overflow in this case).

Solutions

Index of recommended solutions

• You have only an EXE file, no Pascal source
  
  • ask the person who does have the pascal source for a new or recompiled version
  • TpPatch   Patch program for existing executable files
    (caution: only for programs that no not require correct timing)
  • if you need correct timing, you may experiment with tp7p5fix from the other solutions below, it doesn't tell if such programs work with that or not (probably not but maybe worth a try).

• You have pascal source and the Turbo Pascal compiler
  • T7TplFix   patch program for Run Time Library file (TURBO.TPL)
  • NewDelay   unit with delay replacement (good) and error trap (a bit dubious)
  • RDelay   unit with delay replacement and runtime patch routine
  • extract the file CRT.DIF from T7TplFix, apply the listed changes to CRT.ASM and then recompile the run time library yourself. (Only possible if you have the source of the run time library, i.e. you have Borland Pascal, not Turbo Pascal.)

Index of other solutions

bppatch   Solution by German computer magazine c't

contains description, program patch, source patch and copy of patched run time library
problem: rtl is based on version 7.0, thus reintroducing several old errors while fixing one new one, description and patch are very good though.

bp7patch   patch program for all Run Time Library files

problem: does much more changes than can be easily explained

tp7p5fix   TSR program, catches error while program starts

problem: no description available how and how well this program works,
probably only for programs that do not require precise timing

tpbug   new TPL files

problem: contain much more changes than can be easily explained

Comments

Programmers using Turbo Pascal 7.01 can now solve their problem since t7tplfix.zip is available. Programmers using Borland Pascal 7.01 and still must search and apply the patch themselves to get a working version of TPP.TPL (for protected mode). Users without source of their programs can still not get a real solution if the programs rely on a precise delay function. Such a solution will probably never exist.

Of the two files recommended by Borland, one will cause the delay procedure to not run correct on fast computers, the other can be used only by owners of the full Borland Pascal package because the file TPP.TPL is required and it does a lot of suspicions changes to other units as well.

By using any of the other files, you must send your customers a program that is patched to patch itself at runtime with even its authors saying that this is not very nice. Or you can prevent the run time error but must live with a delay procedure that is known to run at unpredictable speeds. Or you must persuade your customers to install a TSR program that you don't know precisely what it does. Or you reintroduce all the bugs of Borland Pascal 7.0 when replacing a otherwise correct version 7.01 with a patched version 7.0. Or you can used a patched run time library that contains a lot of additional changes that nobody has yet explained.

It is a shame for Borland that they seem to be unable or unwilling to solve this bug themselves and offer download of fixed TURBO.TPL and TPP.TPL files from their web page!

If you feel like you should say Borland what you think about their support, please remember they have changed their name to Inprise, so you may try mailing to customer-service@inprise.com (if you get a reply, please tell me).

What's New

• 26-May-1999 new patch for Runtime Library of Turbo Pascal versions 7.0 and 7.01
  A new version of t7tplfix.zip is available here.
  It should be able to patch files TURBO.TPL, TPP.TPL, and CRT.TPU of Turbo Pascal and Borland Pascal versions 7.0 and 7.01.
  Please note that I still recommend updating to the bug fixed version 7.01 that could already be patched with the previous version, but if you don't want difficult discussions with Borland, this is an alternative to fix at least the most annoying bug.

• 29-Sept-1998 similar Bug found in Windows-95
  Borland is not the only company that didn't expect computers to become that fast and thus having bugs in their progams: A similar error has been found in Windows-95: on computers with an AMD K6-2 with 350 MHz or more the driver IOS.VXD causes a division by zero because it contains a timing loop that overflows on computers with too high speed.
  For more informations about this see www.amd.com/products/cpg/k623d/win95_update_k6.html. This problem is solved by the patch amdk6upd.exe that can be downloaded from Microsoft (go to their homepage, click on search and enter the filename) or try this webpage (link probably works only limited time because Microsoft often rearranges their web pages).

• 22-Aug-1998 Patch Program available T7TplFix.zip
  patch for run time library TURBO.TPL of Turbo Pascal 7.01

• 22-July-1998 new version of bp7patch.zip
  does not require TPP.TPL any more, i.e. works if you have Turbo Pascal, not Borland Pascal

Web-Pages

Official and of no big help:

• Borland's Pascal Developer Support
• Intel Developer Support

Inofficial but much more help:

• J R Stockton's Borland Pascal Time and Date Page
• Stefan Göhler's TP-BUG page
• Franz Glaser's Pascal+Delphi site (click on patches)

• my Pascal Page
• other Pascal Pages