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"No CPU emulation" mode?

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First post, by Vendermarch

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Hi.
Is it necessary to emulate CPU speed? I mean leaving an option in DOSBox which would leave the CPU emulation so that only DOS and sound would be emulated. I had the games like Doom in mind in which the CPU speed emulation takes the most of processor time.

or am I wrong?

Reply 5 of 23, by neowolf

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You mean running a virtualized processor instead of emulated - say if you're using an x86 machine accessing the real processor directly? If so then no, as that'd take a lot of work, but performance wise the dynamic core is kinda close to what you're asking.

Reply 6 of 23, by Lofty

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The in-built DOS support in Windows NT/XP basically does what you're suggesting DosBox do. It just does it badly, especially the sound (which is what VDMSound was made for - to replace the sound emulation part).

Basically, using the CPU directly instead of using an emulated CPU, while still running another O/S alongside like Windows is hard, because the program you want to run was designed to have access to the whole computer, and not co-exist with other stuff running at the same time. Seperating the program you want to run from the O/S can either be done by emulating a virtual machine, including CPU, or a more advanced method called virtualisation, the best example of which, is probably the commercial "emulator" VMWare. But even virtualisation has overhead and can be pretty slow. There is actually a virtualisation "emulator" designed for running dos games called DosEmu, but it's only for Linux.

Reply 7 of 23, by gulikoza

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Virtualization would probably speed things up a lot (VMWare runs XP and recent Linux desktops without much problem on modern computers) but it has already been decided that developers will not spend time building another cpu core. Besides, a "virtual" core would require x86 cpu, while "dynamic" can run on any cpu that might be used in the future (although it's true that it only supports x86 at te moment).
But since DOSBox is opensource, you are free to build a new cpu core yourself. I'm sure everybody will appreciate it 😀

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Reply 8 of 23, by eL_PuSHeR

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I have heard that latest Macintosh are built using Intel processors (X86/64 architecture).

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Reply 9 of 23, by Vendermarch

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Yep that's what I needed to know.
Although I hoped for something like> Sure! It will be included in the next release."
You see even TES: Arena runs choppy even on dynamic core with 16000 cycles (on 1900 MHz CPU). So that's what left me wondering.

Reply 11 of 23, by HunterZ

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On my 2.2GHz system, using a recent DOSBox CVS build, Arena runs fine at around 40000 cycles on dynamic core. If you're using 0.63 then you should try a CVS build (see the link in my sig).

Reply 12 of 23, by `Moe`

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Basically, what you ask for is QEmu. It is a kind of cross-breed between DOSBox and VMWare - it has full software CPU emulation like DOSBox, but on some platforms it can also do virtualisation like VMWare. It only emulates a sound blaster card, but that should suffice for newer performance-demanding games. It can run Windows 9x. It does NOT include it's own DOS, so you have to go through the hassle of setting up a disk image.

Oh, and it's cross-platform free open source software, just like DOSBox. All my PC games work with one of these two, a good team.

Reply 13 of 23, by eL_PuSHeR

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Last time I used QEMU for Windows it was utterly user-unfriendly. Talk about DOSBox being hard to get into.

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Reply 14 of 23, by DosFreak

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huh? There's a frontend for Qemu that does anything you'd ever want to do if your too lazy to use the CLI commands.

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Reply 18 of 23, by Lofty

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I've just been playing around with QEmu. Pretty cool stuff!
The virtualisation mode doesn't seem faster than the dynarec for games though. The performance of both is roughly the same as the dosbox dynarec.