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View topic - SMS Test Suite - work in progress homebrew

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  • Joined: 05 Nov 2014
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  • Location: Auckland - NZ
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Post Posted: Wed Jan 05, 2022 12:28 am
Just a thought.. the new issue around 26 cycles for vpd writes as being discussed in the phantsay star thread could actually be a good way to test between a 2 asic and a 1 asic game gear assuming that it applys to all 2 asic models. If i get some time i might dig out some 2 asic units and see if they all show that same issue.
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  • Joined: 05 Sep 2013
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  • Location: Stockholm, Sweden
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Post Posted: Wed Jan 05, 2022 10:18 am
unfortunately this seems very inconsistent so far, with 2 ASIC GGs that can both work 100% fine or not depending on the cartridge of choice (and maybe even something else, who knows!)

but sure we can keep on investigating and maybe we'll come to some better conclusion and hopefully develop a deterministic test for that.
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  • Joined: 22 Apr 2018
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Post Posted: Thu Jan 06, 2022 6:35 pm
I wonder if the CPU loop can be phase-locked to the VDP clock using vblank interrupt and then deterministically phase-shifted using careful choice of preceding instructions by their number of T-states? If so, perhaps we will discover it is reliably broken at some phasing and fixed at others? Also a tight loop reading VDP register changes might be able to determine VDP cycle phase and then sync CPU by choosing following CPU instruction accordingly, in case interrupt handling is too jittery
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Post Posted: Fri Jan 07, 2022 3:03 pm
my understanding is that the VDP is clocked 3 time faster than the CPU so no matter how you count the clocks on the CPU side, you'll end up always at the same phase offset with the VDP. Also the VRAM access 'slots' are not evenly distributed so it's kind of impossible to sync with those, and it's not even the point - what I'm looking for is the lowest always safe cycle count between two successive writes after all, so I'm not really interested in finding that, say, 25 cycles is safe in *some* cases.
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  • Joined: 05 Sep 2013
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Post Posted: Thu Jul 14, 2022 7:43 am
If someone can provide linearity test images like these ones for 256×224 pixels and 256×240 pixels video mode I could add them on the linearity test when using an SMS II ...
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Post Posted: Sat Jul 16, 2022 9:36 pm
sverx wrote
If someone can provide linearity test images like these ones for 256×224 pixels and 256×240 pixels video mode I could add them on the linearity test when using an SMS II ...


I believe that for both of those modes you can literally just take a screenshot from an SNES emulator running in pixel-perfect (1:1 PAR) mode showing the NTSC and PAL linearity test images for 256x224 and 256x239 resolutions, and add one black line to the 239-row one

edit: or the Genesis/Mega Drive version, of course :)
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  • Joined: 22 Dec 2004
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  • Location: UK
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Post Posted: Mon Mar 20, 2023 4:02 pm
@sverx

Has there been any progress on bringing Maxim and Vingazole's work together with your own for testing the Light Phaser in your 240p test suite?
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Post Posted: Tue Mar 21, 2023 8:17 am
Ahem... really, no, sorry. :(

I might try to do that when I've got some free time but it's not that easy, and I also need to make up some space in the current ROM because I'm already at around full 32 KiB, which I'd like to keep as an upper limit so that it can be 'burned' into a no-mapper cartridge.
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  • Joined: 22 Dec 2004
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Post Posted: Tue Mar 21, 2023 9:47 am
sverx wrote
Ahem... really, no, sorry. :(

I might try to do that when I've got some free time but it's not that easy, and I also need to make up some space in the current ROM because I'm already at around full 32 KiB, which I'd like to keep as an upper limit so that it can be 'burned' into a no-mapper cartridge.


No worries. :)

I just thought I'd ask as the latest version of the 240p Test Suite has a Light Gun test now; obviously this is not the same thing but inspired by.

I was thinking maybe a more complete test that could give you the screen numerical coordinate readout in real-time and maybe some clever way of reading the photo-sensitivity of the diode in the gun with it outputting a metric too.

That would help with distance or brightness setting of the display, or possibly help diagnose the quality/age of the Light Phaser. Also some kind of target practice screen. :)

If you are struggling for space then just having a separate rom would probably be a better idea. One could potentially create a more fun test rom; using sprites from other SMS games in a Gallery Shooter type arrangement.
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  • Joined: 22 Dec 2004
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Post Posted: Thu Mar 23, 2023 8:21 am
It seems Ben Ryves has also made a piece of software for the Light Phaser, stumbled upon it on Youtube
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