Help with Copier RAM Test

[8bitwizard]

A real good memory test is the "walking bit" test.

Basically, you write a pattern of 1 0 0 or 0 1 1 repeated through memory, and then verify that it didn't change during writing. Then you try the next two positions. So you end up writing groups of 3 words through memory::

Code: Select all

1 0 0 1  0 0 1 0  0 1 0 0  1 0 0 1 = $9249
0 0 1 0  0 1 0 0  1 0 0 1  0 0 1 0 = $2492
0 1 0 0  1 0 0 1  0 0 1 0  0 1 0 0 = $4924

The first time you write and verify 9249/2492/4924, the second time you write 4924/9249/2942, and the third time you write 2492/2924/9249. Then you do it all over again with the complements of those values.

[MottZilla]

Yes that may well work for testing RAM, but the problem here was the RAM is emulating ROM. Meaning your test program cannot actually write to this memory. So all tests would have to just fix some known data in ROM and perform some sort of checksum or other test or have a serious of such tests to try to figure out if it's working properly.

But as I said, the problem is known to be a hardware issue now. And I have a replacement part on the way which I expect or atleast hope will solve my issues with it. Though I suppose I could still test it by doing what I mentioned and "borrowing" the checksum routine in Gunstar Heroes or another game and expanding the ROM to 32mbits, filling the extra space, and testing on an emulator for the correct checksum result and then put that in for failure/pass and try it on the DPF after.

But I've been assured the new RAM has already been tested so I'm not too worried. I'll probably just try the games I know wouldn't work before and if they work I'll be happy.

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Update: I got a proper RAM Board. Everything seems to work fine now, atleast games that didn't work before work now.

Final Update: To check the new RAM I did was I thought about earlier. I took Gunstar Heroes, expanded it to 32 Megs, dumped the last 24 megs of Ultimate MK3 in the new space, and adjusted the checksum code to include the extra 24 megs in the test. It works and the new RAM passed the test so it should be 100%, atleast I sure hope it is.