bachus Posted August 25, 2021 Share Posted August 25, 2021 (edited) Hello folks, A quick ask for advise, if I may... I plugged in my 130XE and run a quick Memtest. It started off as normal, but as soon as it hits the 18th location, the text turns into garbage. But all RAM/ROM and all locations are green. I captured this short video on its 3rd test loop already (therefore the text is already garbled) to show what's happening but get the idea... This behavior repeats on every loop, at the same and one location only. Do you think this may be something I need to be worried about? Please let me know and thank you for your time. 130XE_Memtest_3rdloop_082521.mp4 Edited August 25, 2021 by bachus Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted August 25, 2021 Share Posted August 25, 2021 In spite of what the results are showing that does look like either a RAM or ROM issue Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted August 25, 2021 Share Posted August 25, 2021 The POST on the Atari is not a thorough walking bit or other such extensive ram test, please try the main bank /extended bank swap method outlined on the forum. There is a good chance the issue will go away. The next places to look failing that test would be Antic/OS/GTIA. If none are at fault check out the memory support chips/mmu. That's basically quick and to the point run down. Quote Link to comment Share on other sites More sharing options...
Rybags Posted August 25, 2021 Share Posted August 25, 2021 Is the text normal at other stages of the test? Some sort of memory selection problem maybe - CHBASE is $E0 during this test as normal but obviously Ram is being red instead of the character set. Given it's changing then it's probably either low memory or the actual memory being tested at that point (which would assume CHBASE = $48 I think) 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted August 25, 2021 Share Posted August 25, 2021 heh, didn't realize it was a video, does the video change all through the test or on only during the certain blocks, a block isn't correlated to a certain ram chip but rather a series of bits across the chips. Given this information it may well be the latter portion of the quick list I shot your way. Quote Link to comment Share on other sites More sharing options...
Rybags Posted August 25, 2021 Share Posted August 25, 2021 It could be a faulty MMU that's causing certain banking combos to redirect OS Rom accesses elsewhere - though the mystery then becomes why doesn't it just crash? Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted August 25, 2021 Share Posted August 25, 2021 (edited) Antic holds the character set so it may be kaput. the GTIA doesnt know any better, it just displays what its told to. Ive seen ones that fail this way and they seem to function normally-ish except the character set is garbled. Edited August 25, 2021 by xrbrevin 1 Quote Link to comment Share on other sites More sharing options...
bachus Posted August 25, 2021 Author Share Posted August 25, 2021 3 hours ago, TGB1718 said: In spite of what the results are showing that does look like either a RAM or ROM issue 2 hours ago, _The Doctor__ said: The POST on the Atari is not a thorough walking bit or other such extensive ram test, please try the main bank /extended bank swap method outlined on the forum. There is a good chance the issue will go away. The next places to look failing that test would be Antic/OS/GTIA. If none are at fault check out the memory support chips/mmu. That's basically quick and to the point run down. Thank you for the rundown of things to check. I haven't really done troubleshooting like this before, so this is going to be interesting. I will look for the bank swap on the forums and hit up YT for some tutorial videos. Thx. 1 hour ago, Rybags said: Is the text normal at other stages of the test? 1 hour ago, _The Doctor__ said: heh, didn't realize it was a video, does the video change all through the test or on only during the certain blocks, a block isn't correlated to a certain ram chip but rather a series of bits across the chips. Given this information it may well be the latter portion of the quick list I shot your way. So, the test starts just fine, with the text intact. Then on the 1st look, as soon as it hits that 18th square, the text flips through characters in the video, then stops as soon as it moved to 19th square. It then completed the loops, all green. Then starts next loop, all OK until the 18th square, and same happens. And so on... 1 hour ago, Rybags said: It could be a faulty MMU that's causing certain banking combos to redirect OS Rom accesses elsewhere - though the mystery then becomes why doesn't it just crash? I ran the test for about 30 mins, and it never crashed. The machine seems to work fine otherwise. I played some games, ran some demos and no issues I can tell. Never hangs, and this is the only time I've seen the text garbled in any application. Alright, sounds like I have some testing ahead of me. Thank you for the pointers. Quote Link to comment Share on other sites More sharing options...
Krenath Posted August 27, 2021 Share Posted August 27, 2021 Don't know if it's any kind of a clue, but those garbled shapes are the bit patterns for consecutive numbers. Wherever it's getting its character data from right now is just a bunch of 0 1 2 3 4 5 6 7 8 9 A B C D E F...etcetera Quote Link to comment Share on other sites More sharing options...
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