[Simh] Simulator development: Advice on system timing

[Paul Koning]

> On Oct 26, 2017, at 2:23 PM, Armistead, Jason <Jason.Armistead at otis.com> wrote:
> 
> If you need accurate device timing, then perhaps something like the core of MAME/MESS is a better choice than SIMH.  All those retro arcade machine games in MAME depend on counting cycles in order to give realistic game behavior for the human who is playing them.  If they ran twice as fast, they'd be unplayable (or at least, very challenging), so everything is carefully handled to ensure it runs smoothly at a realistic rate.
> 
> Maybe not the answer you're looking for, but it is one alternative.

I didn't know about MAME, thanks.  Then again, both computation and I/O can look pretty realistic with SIMH with instruction pacing enabled (set to the average instruction time).  You're quite right that this isn't exact, and if you have real time software (like games) that would be visible.  But it's quite good enough to give you a "oh yes, it really *was* that slow" experience.  :-)

	paul