[shusaku]

> For Brembs, older PCs offer another crucial feature that was lost when Microsoft replaced its text-based operating system, MS-DOS, with Windows. MS-DOS “handles data as they come in with no buffering delays”, says Brembs, who exploits this feature for his fruit-fly flight simulator. “In Windows, so many things are constantly happening in the background,” Brembs says. You might want to take measurements at intervals of precisely 50 milliseconds, but the operating system might be able to manage only an average of 50 ms, with intervals ranging from 20 to 80 ms, depending on what else it has to do.

This is pretty interesting, I wonder if there are special ways to get around this, or if you’d need something like an fgpa.

[greenbit]

Got a chuckle out of that section - DOS as an RTOS. But yeah, makes sense, about the only thing on the metal besides your application would be the timer interrupt, and didn't they use a DMA channel for dynamic RAM refresh? You wouldn't have some preemptive scheduler slicing your time with 50-odd instances of svchost.exe, there'd be no virtual memory page swapping going on. With just your application code running, the caches should even stabilize.

[dghlsakjg]

This is what an RTOS solves in embedded systems.

If you want to know exactly what clock cycle/time interval something is going to happen on, the easiest thing to do is just use a microcontroller.