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First post, by Danfun64

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Hello. I'm curious as to what Hz each cputype (386 | 386_slow | 486_slow | pentium_slow | 386_prefetch) is supposed to be equivalent to. In this case, I'd like to set PCem to the equivalent of DOSBox's "pentium_slow" setting (I don't want to overshoot the mark).

Reply 1 of 6, by Qbix

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They have nothing to do with HZ or speed at all.
It controls the features available. Slow and fast control which algorithm is used when dealing with pagefaults.

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Reply 2 of 6, by leileilol

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Also they'll never be equivalent as DOSbox treats all instructions as one cycle. Different games have different demands. Even 3000 cycles isn't consistently reflective. Don't trust TOPBENCH either (which was made on the pretense that you could tune dosbox to 'match' an older PC to get some placebo effect of emulation authenticity)

by the way, DOSBox is not for running Windows 9x

Reply 4 of 6, by Kerr Avon

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Incidentally, why doesn't DOSBox have an option to act specifically like a given PC, at a given speed? Such as

/basetype 286 /mz 12

/basetype 486dx /mx 66

I can see that this would at best be only an approximation, since two 486DX 66 PCs, for example, could have vastly different hardware so that not only is one PC noticeably faster than the other, but actually the slower one might be faster than the fast PC in a specific component, and also that DOSBox doesn't emulate cycle accuracy (which doesn't matter, of course - DOSBox is brilliant for games!) but wouldn't the ability to choose (roughly) the speed of the emulated PC be useful for some people?

Apologies if I'm missing some obvious technical reason why this is a stupid or impractical option (I probably am).

Reply 6 of 6, by Jo22

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Kerr Avon wrote:

Incidentally, why doesn't DOSBox have an option to act specifically like a given PC, at a given speed?

Well, not all 386es and 486es had the same cycle timings either. Especially the 80486 platform had many clones.
Of course, we could go with the intel ones as reference. But not all users would agree on that, since many had clone chips.
Personally, when I think of 386es, I think of the AM386DX40, which never got an Intel complement. 😐

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