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Posted Tue Jul 31, 2012 11:42 AM
Posted Wed Aug 1, 2012 2:50 AM
Posted Wed Aug 1, 2012 7:42 AM
I don't know about MMU type not supporting 2MB of RAM. IMP brand supports not 2.5 MB (will see only 2 then) - that's what I expereienced. I guess that problem is somewhere else.
Ops. You can not expand from 1MB to 2MB just like that. 1MB uses both banks. Only way is to replace whole RAM with 1Mb chips (instead 256Kb ones). It may be done by leaving original chips in board, but deactivationg them by connecting all CAS/RAS/WR lines to high. And adding board with 2MB RAM - but max 16 chips total. I have one.
Considering IDE for 1040/520 ST: http://atari.8bitchip.info/aidesch.htm
Posted Wed Aug 1, 2012 9:28 AM
Posted Thu Aug 2, 2012 6:39 AM
Old MMUs work fine with 2 or 4MB. I had couple 520 STs, and all worked with 2MB RAM well.
Check again all your connections, solderings. And possible too that some chip is faulty.
Or you soldered bad some adress line.
Of course, it is easier to replace MMU chip - but I bet that error is somewhere else. And you need to buy that chip.
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