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Macintosh II Ram Config ...

Posted by: franklyn on 2026-09-20 11:07:10 I have a Macintosh II with a 030 CPU and the SE30 ROM that is running perfectly with four 1MB SIMM modules installed in Bank A and four 256KB SIMM modules in Bank B. I have a lot of additional 1MB SIMM modules that all work without issues in a PC. However, if I populate Bank B with four 1MB modules as well, I always get the "chimes of death." What is causing this, and exactly which memory modules do I need to reach 8MB? And what I need for install 8 modules a 4MB for a total of 32MB?

Posted by: Bolle on 2026-09-25 00:13:15 Do the non-working 1MB modules have 2 or 8 RAM chips on them? Two-chip SIMMs can be problematic in the Mac II (and IIx for that matter) for the same reason that 4MB and 16MB SIMMs fail. Newer high density DRAM chips have a test mode that gets triggered by way the Mac II and IIx are sequencing the RAM read/write signal. If you want to use 4MB or 16MB SIMMs in a Mac II or Mac IIx you will need "PAL SIMMs". Those have logic on them to work around the write signal sequence issue that sends high density DRAM chips into test mode. You could go and built your own SIMMs: https://github.com/kr239/Macintosh-IIx-RAM-SIMM

Posted by: franklyn on 2026-09-27 06:52:46 This is easy to build, I will try 8 SIMM to build by use old two 16MB P/S2 SIMM with 17400 Chips ... RAMSIMM-30/GW4194-4MB-CBRFIX-SOJ-DP at release · garrettsworkshop/RAMSIMM-30 4 MB and 16 MB 30-pin DRAM SIMMs. Contribute to garrettsworkshop/RAMSIMM-30 development by creating an account on GitHub. github.com

Posted by: franklyn on 2026-10-04 12:23:01 A10 was missing at the Bank B ...

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