Writing emulators [Was: Re: VCF PNW 2018: Pictures!]

Al Kossow aek at bitsavers.org
Wed Feb 21 13:09:46 CST 2018

On 2/21/18 6:41 AM, Paul Koning via cctalk wrote:

> SIMH in principle allows the writing of cycle-accurate CPU simulators, but I don't believe anyone has bothered.

Atari 2600 requires it.
Any simulation of an embedded system that did cycle counting for timing
would require it as well.

One situation that isn't handled correctly in MAME right now is where a CPU is stalled by holding /WAIT
or /DTACK off to wait for a peripheral to acquire data, the way that the Tarbell floppy interface works,
for example.

That is tricky to cleanly and efficiently implement where each component is modeled independently and
glued together with a higher-level framework.

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