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First post, by SquallStrife

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So I'm one of the lucky ones that got his Raspberry Pi embedded Linux system last week. 😀

Of course the first thing I tried was DOSBox. First I tried 0.74, then CVS, both compiled from tarballs.

The problem is the performance. It's sporting a 700MHz ARMv6, which I thought would be enough to run Commander Keen 4 at full speed. And it seems to be...

...until the screen starts panning, then the framerate stutters. If Keen is moving around, firing off his raygun, everything is sweet. But if you try to start running through the stage, the framerate takes a dive, and CPU usage hits 100%. I also tried ScummVM, and experience the same issue, your character can move just fine, but if the view pans, things get sad.

I mention this, because both packages use SDL., and at the moment the RasPi only supports SDL via software-rendered directfb.

Do you reckon that performance will improve, if SDL could be made to output using some GPU accelerated method, perhaps thru OpenGL ES?

Second question, does DOSBox use much floating-point arithmetic? There are two Linux builds for the RasPi, one that's complete but only has software floating-point support, and one that's incomplete but has hardware floating-point support.

I couldn't see any difference between the two in terms of DOSBox performance, however, this could be due to the SDL/directfb issue.

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Reply 2 of 6, by Freddo

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SquallStrife wrote:

Second question, does DOSBox use much floating-point arithmetic? There are two Linux builds for the RasPi, one that's complete but only has software floating-point support, and one that's incomplete but has hardware floating-point support.

That depends if the game you try to run use it or not (Commander Keen 4 do not).

bloodbat wrote:

Looking at the specs...I don't think the hardware's powerful enough...

Indeed, my phone have a 600MHz ARMv6, and it's too slow to run anything I tried on it decently. Another 100MHz won't really change that.

Reply 3 of 6, by Zup

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Some time ago, I posted about the performance of DOSBOX on Wii. I'm insterested about the performance on the Raspberry (I've purchased one of those). Could you set cycles=max, run Navràtil and post the results?

Thanks.

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Sometimes going all the way is just a start...

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Reply 4 of 6, by grazzt

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This is way late I guess, but with the included dosbox from the raspian repos, Im getting about 3100 dhrystones in the nav cpu benchmark. nssi detects it as a 2 mhz cpu. 😀

Scores lower than a 286.

And sounds about right, dosbox is slowwww on the pi.

I would try other benchmarks, but it just takes waaayyy too long to even load them.

Now perhaps the binary is compiled wrong or something, but I doubt it, so I guess dosbox is just not feasible on the pi. 🙁

edit: with cycles left at 3000 (and not max like what was above), nav is giving me ~6800 dhrystones, and scoring about a 386-sx25. so I guess max cycles is not the best. More testing will be done...

edit: its actually about the speed of a low end 386, xcom works (barely playable if you have patience). master of magic also works (again would require patience).

so actually not bad for a 700mhz arm. 😀

Reply 5 of 6, by Kerr Avon

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It's the same with the XBox (the original XBox, not the XBox 360) - the XBox has a P3-733 Mhz CPU, and there are a lot of great emulators ported for it, such as SNES/Megadrive/MAME/Atari ST/ZX Spectrum/C64/NES/etc. They all run fast enough to play their games, unlike DOSBox, which on the XBox runs at the speed of about a fast 386. It's a real pity, as I'd love to be able to play Carmageddon, Blood, System Shock, etc, on the XBox, but the overheads of DOSBox seems to be much too high.

Actually, nowadays I have my PC plugged into my TV, so it's not something I miss now, but five or six years ago I'd have loved to play DOS games on the XBox. Anyway, aside from the speed, I have no complaints about DOSBox - well, snapshot load/saving would be nice, as would the ability to pause DOSBOx then insert/remove CD disc images by a file selector from DOSBox itself, but they are minor things that I can well live without. I just wish DOSBox was faster, but I imagine that it's pretty much as optimised as it can be, or else others would have released faster builds by now. And from what I've read, DOSBox does emulate a lot hardware, so it's (relatively) slow speed is a necessary price for it's accurate emulation. Either way, it's still a great piece of software, and makes it possible for us to play our old favorites on new machines.

Reply 6 of 6, by VileR

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Kerr Avon wrote:

It's the same with the XBox (the original XBox, not the XBox 360) - the XBox has a P3-733 Mhz CPU, and there are a lot of great emulators ported for it, such as SNES/Megadrive/MAME/Atari ST/ZX Spectrum/C64/NES/etc. They all run fast enough to play their games, unlike DOSBox, which on the XBox runs at the speed of about a fast 386.

Those systems are actually nowhere as powerful as a fast 386, so if DOSBox can achieve that performance on an XBox, it's actually doing pretty well next to those other emulators.

It's a real pity, as I'd love to be able to play Carmageddon, Blood, System Shock, etc, on the XBox, but the overheads of DOSBox seems to be much too high.

It's rather your expectations that seem to be much too high... If you want a valid basis for comparison, why not try DOSBox with PC games from the same timeframe as those other systems ('80s through early '90s), as opposed to Carmageddon?

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