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Test case for the MSX2 driver #87966
05/02/13 12:49 PM
05/02/13 12:49 PM
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Dr.Venom Offline OP
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Dr.Venom  Offline OP
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Hi,

I've encountered a nice MSX2 picture demo that possibly provides a good (challenging?) test case for the MESS driver. The Demo is called 512colors and uses some VDP tricks to show 512 color pictures interlaced in screen 7. (Normally a 256 color fixed palette.) This is achieved by changing the palette on a scanline basis. The demo can be downloaded here.

Currently it does not work correctly in MESS. Below are comparison screenshots with MESS on the left and how they should appear on the right:







Interestingly there's also a whole forum thread dedicated to the making of that demo, explaining and discussing the logic behind it in more detail. See here:

Idea for math experts...

In that thread are also links to the ASM sources, but I also noticed they are included on the demo disk:



Given that background information I thought it might provide a useful test case for possibly improving the MESS emulation.

P.S. Now I guess we only need a certain someone breaking himself free from that BBC and Atari stuff smile

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87978
05/02/13 05:59 PM
05/02/13 05:59 PM
Joined: Apr 2004
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judge Offline
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My kids want some attention too :P

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87979
05/02/13 06:15 PM
05/02/13 06:15 PM
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R. Belmont Online content
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And fixing "extreme" effects like this rarely translates to actual compatibilty, unfortunately.

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87980
05/02/13 06:33 PM
05/02/13 06:33 PM
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Haze Offline
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but would still be useful to have documented in the software list (with any other relevant information as notes there, for people who might want to look at it)

extreme tests cases ARE good to have around, although I'm not sure changing the palette per-line is extreme, although maybe the MSX doesn't have counter / timer hardware to make it easy (I don't know, such cases are used on the spectrum and really are extreme because they come down entirely to cpu timing, and yes, some games use them there)

(and before anybody screams 'modern homebrew!!!' the goal is to have the best emulation right, therefore it makes sense to have the best test cases documented and close at hand)



Re: Test case for the MSX2 driver [Re: Haze] #87981
05/02/13 06:42 PM
05/02/13 06:42 PM
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Posts: 4,625
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Anna Wu Offline
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First we need an maintainer for the MSX driver.

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87982
05/02/13 07:15 PM
05/02/13 07:15 PM
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R. Belmont Online content
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Since when has "modern homebrew" *ever* been a reason to avoid accuracy in MESS? Or even MAME, for that matter? The dkong driver was rewritten from scratch to the D2K author's specifications, we've used a bunch of byuu test programs on the SNES driver, and I have my working Apple IIgs right next to my PC running MESS for experiments.

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87983
05/02/13 07:47 PM
05/02/13 07:47 PM
Joined: Apr 2004
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judge Offline
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On the msx2 with the 9938 you of course have line irqs, from there on you can do nice cycle counting to trigger effects on special locations. Of course this would require you to swap out the bios irq routines in favor of your own routines, but it's certainly possible.

Re: Test case for the MSX2 driver [Re: R. Belmont] #87984
05/02/13 08:32 PM
05/02/13 08:32 PM
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Posts: 3,687
Trondheim, Norway
etabeta78 Offline
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Originally Posted By R. Belmont
Since when has "modern homebrew" *ever* been a reason to avoid accuracy in MESS?


because Haze refuses to load anything from fullpath, so if it's not in the softlist he cannot test

Re: Test case for the MSX2 driver [Re: etabeta78] #87985
05/02/13 08:37 PM
05/02/13 08:37 PM
Joined: Jul 2007
Posts: 4,625
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Anna Wu Offline
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Anna Wu  Offline
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Originally Posted By etabeta78
Originally Posted By R. Belmont
Since when has "modern homebrew" *ever* been a reason to avoid accuracy in MESS?


because Haze refuses to load anything from fullpath, so if it's not in the softlist he cannot test


grin

Re: Test case for the MSX2 driver [Re: Dr.Venom] #87987
05/02/13 08:54 PM
05/02/13 08:54 PM
Joined: May 2004
Posts: 1,555
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Haze Offline
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I just find it hilarious that some people don't think we should document the very things that help improve the actual emulation in the projects, as eta's post kinda proves.

there's nothing quite like a test case that screams 'your emulation sucks' at you if you make bad changes than one specifically designed to tell you so, therefore documenting such cases using the mechanism we have for documenting things makes one hell of a lot of sense.

unless I'm misreading RB's post, he also agrees.

I'd really like to see some devs create extensive test software to run on real hardware, and in MAME, and document said software in MAME to show exact sprite limits and the like for arcade hardware, you get a known reference point, actual values, and software that people can easily try on different revisions of arcade hardware too. That makes the emulator better.


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