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  • Joined: 05 Sep 2013
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SMS memtest
Post Posted: Thu Aug 13, 2020 2:36 pm
Last edited by sverx on Fri Aug 14, 2020 1:14 pm; edited 1 time in total
So I just started working on this, which might then later get merged into the SMS Test Suite (not sure it can be easily done, we'll see...).

Ideally, after the RAM tests, there will be similar VRAM tests and, after that, there might even be CRAM tests, even if they'll likely be 'visual' tests as there's no way to read back from CRAM to see if the written values were written/retained correctly.

So this is just a small preview now, with just few simple tests. For each test, the whole 8 KB system RAM is written, and a little delay applied before reading back the values again so that if a memory chip isn't retaining the written values properly, tests should appear as failed. Note that pressing the console's PAUSE button will trigger the NMI, which will write the current value of the program counter register onto the stack, which is in RAM, so the test that is running at that moment will report a failure. This is expected and it doesn't mean RAM is faulty (so, in short, PAUSE should *not* be pressed when tests are running).

Please give feedback and suggest more memory tests, if they can be useful. I will set up a GitHub repository later.

EDIT: version 0.01 removed. See below for newer versions.
SMSmemtest1.png (11.42 KB)
SMS memtest all tests OK!
SMSmemtest1.png
SMSmemtest2.png (11.46 KB)
SMS memtest one test FAILED
SMSmemtest2.png

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  • Joined: 05 Nov 2014
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Post Posted: Fri Aug 14, 2020 3:20 am
This looks neat! I guess if you had the 3d glasses adapter plugged in youd see each eye swap when it goes from all 0 to all 1.

Actually.. that in itself could be a handy test to add to the sms test suite.. 3d glasses functionality test. Left eye open, right closed. Then click a button and they swap.
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Post Posted: Fri Aug 14, 2020 9:10 am
wasup wrote
I guess if you had the 3d glasses adapter plugged in youd see each eye swap when it goes from all 0 to all 1.


I'm writing to $C000-$DFFF only, not to the mirrored addresses, so I'm not writing to $FFF8 and the 3D glasses shouldn't care.

I agree it could be interesting to add a 3D glasses test to the SMS Test Suite. I'll work on this later.
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Post Posted: Fri Aug 14, 2020 1:11 pm
new version - this one run same series of tests on VRAM too, after the RAM tests are completed

VRAM tests are run with screen off - program will stop if a test fails, displaying which one did, or will run to the end of the tests confirming everything is working fine
SMSmemtest1.png (12.49 KB)
SMS memtest all RAM tests OK, press a button for VRAM tests
SMSmemtest1.png
SMSmemtest2.png (10.23 KB)
SMS memtest all VIDEO RAM tests OK!
SMSmemtest2.png
SMSmemtest3.png (9.91 KB)
SMS memtest VIDEO RAM test failure
SMSmemtest3.png
SMSmemtest_v0.20.zip (3.85 KB)
SMS memtest ROM version 0.20

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Post Posted: Fri Aug 14, 2020 1:50 pm
Note that the SF-7000 does some similar tests but it uses beeps to signal failure, because if RAM or VRAM are failing, there’s a decent chance your attempt to draw to the screen will fail.
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Post Posted: Fri Aug 14, 2020 3:57 pm
mmm... is an SMS with completely broken/missing RAM able to boot and get to the point where execution is handed to the cart ROM? I think it needs to execute some code from RAM so probably there's no way to write any software that tests for that condition...

Also, if VRAM is totally broken/missing you're likely getting a solid color on screen. Not sure if it's worth to perform some quick VRAM test and give some beep code if that fails...
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Post Posted: Sun Aug 16, 2020 3:52 am
I realize they aren't exactly"SMS" but I believe both the Mark III and no-BIOS Game Gear models should be able to boot the ROM cartridge in a no-RAM, no-VRAM scenario
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Post Posted: Sun Aug 16, 2020 5:54 am
Ive just run this on a game gear in sms mode and it runs fine, which is expected.

One small change you could possibly do is have it wait for a button press before starting the tests, like it does for the vram tests.
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