Slowdown PC


Thread Starter

Helmut Meissner

Hello List,

We had an old 286 PC in connection with a Phillips PLC. Connection via RS485 with 4800 Baud.

The PC is now broken. Trying a 486PC with 133MHz brings problems with the communication (Lost Data).

The inventers of the compiled GW-Basic program told us that the CPU is too fast, the timing was made with loops. They have no possiblity to
change the programm, because they lost the source.

Does anybody know a solution to slow down a MS-DOS Program.

When I was young I knew about programs to slow down the PC to get better Highscores in games.
Does anybody remember how they worked (Timer-Interrupts on the NMI ?).

Sourcecode would be great. (ASM, TP or C) for a TRS-Programm.


Helmut Meissner
Nassau, Germany

Pierre Desrochers

<<Does anybody know a solution to slow down a MS-DOS Program.>>

We had the same problem a long time ago and I recall having a program supplyed by GE Fanuc for exactly this purpose ... for LM6PC there Serie Six
PLC prg software.

Maybe check with them ...

Hope this helps

Hello Helmut,
here comes a Turbo Pascal TSR source code I used recently to solve a similar problem.
Credits go to Tom Swan's "Mastering Turbo Pascal 5.5" book. Can also be compiled with Turbo Pascal 7.0

Luca Gallina

{$M 1024, 0 ,0} {use minum amount of RAM}
{$N-} {no co-processor}
{$S-} {no stack-overflow checking}

Program xKeep;

Uses DOS;

i, MyDelay: longint;

Procedure Crawl(Flags, CS,IP,AX, BX, CX, DX, SI, DI, DS, ES, BP: word);
MyDelay:= 150000;
for i:= 1 to MyDelay do {wait}

SetIntVec($1C, @Crawl);


Pekka Kuisma

I've experienced the same problem, although many many years ago. I'm pretty sure I still have a copy of those TSR or loadable programs that I've used to slow down the CPU. I will check my archives and let you know.

Pekka Kuisma
Springfield, OH, U.S.A.

Perez, Claudio

We had the same problem with a program to backup SattControl's Midi, and we resolved it with a 386 and the DOS mode command.


Claudio A. Perez
DCS Engineer

Hunter Farris

Ran into this same problem using SYMAX equipment and a laptop. I used the attached program to slow down the processor in MS-DOS. Good luck.

Hunter Farris