Hi everyone.
My RAM Keeper has arrived. I tested it on a ROM 01 machine and there don’t seem to be any major issues, except that I wasn’t able to get the RAM2GSII GW4201D from Garrett Workshop to work, while the official Apple 1MB expansion card worked fine.
My main goal, however, is to get it working on a ROM 03 system. For that purpose, I performed the modification on the 74F27N NOR gate as required.
Now I have a problem. If I leave the original 2764 with firmware 1.4 installed, when I power on the IIgs I get a “nice” (so to speak…) Invalid RK Configuration 0102 error.
I programmed a NEC D27128D with firmware 1.7: Name: RamKeeper_ROM_1.7.bin Size: 16384 bytes : 16 KiB SHA256: 9e932ad068e2e824002e7fb3bcb1b91624548de614306f7c88fcd7cbc01e85b0
However, with that EPROM the IIgs behaves at startup as if the RAM Keeper wasn’t installed at all. Do you have any advice regarding a specific model of 27128 EPROM that is known to work reliably, and possibly any tips on how to program it correctly using a GQ‑4X4 programmer?
Thanks in advance to anyone who can help.