Greenious wrote:ST/STE don't have a separate ram-refresh. It relies on the constant video access to provide ram refresh for the memory
Greenious wrote:which is why they only use Fast Page mode dram.
exxos wrote:I checked RAS,CAS, and all other lines, they are pretty much ok. Its only the MAD lines which suffer, mostly MAD9,MAD8 possibly.
czietz wrote:Yes, but what's the timing between RAS, CAS and the glitches/noise you see on MADx? As already stated, MADx need only to be stable around falling edges of RAS and CAS. Can you make a scope capture showing RAS and/or CAS together with MAD8 or MAD9?
czietz wrote:At least on the scope traces it looks as if the noise / the spikes on MAD9 do not coincide with falling edges of either RAS or CAS. For example for NEC µPD41256 DRAM the setup time for addresses is 0 ns (i.e. addresses must be stable exactly when the falling edge begins) and the hold times after the falling edge are 10 ns (RAS) and 20 ns (CAS). So the address lines don't need to be at the defined level for a very long time.
However, it'll be probably very hard to capture the precise moment when a RAM error occurs. Maybe in that case some glitch does happen at the same time as a falling edge on RAS/CAS. Hence when your buffer board arrives I'll be interested if it fixes the errors.
dlfrsilver wrote:Chris, can you post a picture of your STE motherboard which has a problem with the RAM ?
czietz wrote:What needs to be custom about the RAM test program? Aren't these errors found by a regular RAM test program? Of course, then you can't say if it is the SIMM or the MMU, but I don't see any way to determine this in software.
That being said I always wanted to port memtest86's test algorithms to the Atari, because they are good at finding subtle faults. Never got around to do it, though.
troed wrote:exxos wrote:I assume screen RAM is high up in the RAM map somewhere
Yes. xF8000 where x is 0,1,2,3 depending on the amount of memory in the machine.
edit: ... and 78000 if you only have 0.5MB ...
exxos wrote:dlfrsilver wrote:Chris, can you post a picture of your STE motherboard which has a problem with the RAM ?
Think these STE boards pretty much look the same dont they ?! This is just a later one with the integrated blitter.. Its the first "type" of board I have tried and just so happens to be the first board I've noticed this ram problem.
Someone else has confirmed the spike problems, but he doesn't have any RAM issues (at least that he knows of). I really need a custom RAM test program that I can pass about to people to see if others actually have this fault or not.
dlfrsilver wrote:Ok, when you get this program, i'll volunteer to test my 520 and 1040 STE (both with 4mb) and return the result here.
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