Re: [hatari-devel] Cycle exact 68040/68060 mode in Hatari

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Le 13/09/2016 à 23:21, Thorsten Otto a écrit :
The question is: is a cycle-exact mode for 68040/60 needed or even possible?

If i understand it right, cycle-exactness is needed only for demos/games
that rely on a certain sequence  of instructions to run in a known
amount of cpu-cycles, in order to mess with the video-address or to
switch colors/resolution. Given that there haven't been that much real
machines with 040/060, and the timing of this processors is quite
different depending on cache modes/processor configuration/type of
memory in use, are there really any programs out there that make use of
it and actually work on real hardware? I would bet that such programs
would break on each end every change in configuration.


Hi

that's also true, but maybe in some cases emulation is twice too fast or twice too slow (I haven't checked this real prod) and we'd like to have maybe 10 or 20 % difference only.

Some programs were made for 68060 (using CT2 board for Falcon IIRC), some Amiga demos also require a board with a 68060, but it's true these demo also rarely do tricky video stuff, as the timings can vary greatly depending on the cpu state.

Nicolas




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