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Setting cycles to specific xt/at/386/486/586 speeds

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First post, by inukaze

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Just a dunno from where this value came from in this thread: Re: Set cycles to specific xt/at/386/486/586 speed.

set dosboxcycles=188

i don't understand how you determine this value for 386@16

Reply 2 of 6, by Bruninho

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Since DOSBox has changed a lot in the last ten years, especially on how to set up the speed, I think it would be relevant to get these info for the new versions too.

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Reply 3 of 6, by mr_bigmouth_502

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DOSBox doesn't really work that way. The cycle count in DOSBox doesn't really correlate to the speed of any real CPU; all instructions in DOSBox take only one cycle, whereas on a real CPU instructions may take multiple cycles.

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Reply 5 of 6, by cyclone3d

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A great feature would be to add an auto-setting based on benchmarks of real hardware. Tweakable settings for the different subsystems such as CPU, Video, and RAM would be even better.

In reality, it should be possible to make the speed of DOSBOX much more accurate in comparison to real hardware.

It wouldn't be an easy task, but should be doable if somebody takes the time to do it.

For super accuracy, it would take a whole lot of code changes.. after the current code is optimized.

I've thought about trying to do this in the fork I am planning and have started already working on.

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Reply 6 of 6, by galland101

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I believe PCem is technically a more accurate emulator than DOSBox when it comes to emulating specific hardware such as specific CPU speeds and graphics cards. It requires a bit more technical skill to get it working as you need to deal with gathering firmware/BIOS packages and working with virtual disk files. You also have to install DOS and Windows from scratch on it. You'll also need a CPU with fast single-thread clocks (high-end i5 or i7) to emulate something close to an old P55C 233 MHz. It’s basically a less-polished VMWare Workstation for retro gaming.