One of my summer intern jobs during college was testing old DOS programs to make sure they would run on Windows. This was for a factory that could no longer deploy DOS so they had to go to Windows for support. Most were fine but some used platforms/languagues like Clipper which had a timing loop calculation on startup and of course, as you might be guessing, that loop ended up being a divide by zero. Enough old DOS games had that problem that people had come up with workarounds like having a batch file that kicked off a program that consumed as much CPU as possible, delaying a short while and then starting the problematic program. Due to the other CPU hogging program slowing things down, the timing calculation on startup would take longer and no more divide by zero. I don't know if they actually shipped our solution in the end... The Clipper programs were all in house but apparently they had lost the source code for many of them.
First I thought, this can't be right, DOS didn't have multitasking. But then again, a DOS program adding a timer interrupt could have hogged enough CPU I guess.
Itβs been a while, but I remember the name DoubleDOS. Something that let you run two programs at once my preallocating half of memory in a device driver.
I might have explained it poorly but the multitasking was with the switch from DOS to Windows (I can't recall version which but I think it was 95 or 98) along with new hardware.
