It will be interesting to see what happens once you disconnect the motherboard RAM! Is removing VCC enough? Sometimes chips can still get phantom power over the other wires -- I've seen it on smaller chips, no idea about how RAM chips behave in that case. Maybe you could disconnect the output enable lines and/or chip select lines instead? Just a thought.

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Dunno, all my resting has been very hurried during lunches or tonight, in between work and running over to the grlf's place. Maybe I'll get a chance to play with the MoBo during the next few days. Any suggestions from anyone as to what lines to desolder to make the IIsi's Bank A appear effectively empty are more than welcome!

Why did the stock IIfx ROM work when the modified one didn't? Theoretically they should behave exactly the same if you have burned a standard IIfx ROM image on the modified SIMM (I'm assuming you're talking about the socketed SIMM you bought from me). Does the socketed SIMM still work in the IIfx?

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Yep, it has a standard IIfx ROM Dump burn and boots the IIfx nicely, as does the standard IIfx ROM SIMM, of course. It's strange that the Unmodified IIfx ROM SIMM is working in the IIsi whereas the modified IIci ROM SIMM with the IIfx ROM Image burn doesn't . . .

. . . curious, but unimportant! :b&w:

What's important is to get the IIsi RAM config to look similar enough to a kosher IIfx RAM config to get the IIsi to pass the bootup routines on the IIfx ROM, if the IIsi boots successfully with the IIci ROM Image burn, or the IIfx ROM image burn, I expect to lose the Microphone input support until a ROM tweak becomes available, but that's no biggie!

That's why I tested the IIfx with RAM installed in only Bank B! :approve:

Back to hackin' hardware! Installing an overfull Bank A (and Bank B for that matter) on the SuperIIsi™ is one of the major thrusts of this hack's aims. So long as no Monitor sense lines (?) are detected or color depth info is present in the PRAM, the buffering of the first MB of Bank A appears to be a non-issue!

RAM it to the MAX!!!! :lol:

p.s. thanks for the "MoBo ROM/ROM SIMM jumper tip-off!" ISTR reading about such things, but the only Mac I've ever had around to play ROM SIMM ganes with was my pet IIfx. The IIsi project is very recent, it's code name is "Thumper" . . .

. . . as in thumping every SE/30 variation extant! }