Backward compatibility for ROM cleanliness on the SE/30 is one thing.
However, forward compatibility for increased utility of the IIsi is an entirely different animal!
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I'm waiting to hear which line needs to be cut on the dougg3's IIci ROM SIMM to make it work in the IIsi.
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I'm betting that Apple didn't want either the IIfx or the IIci ROM SIMMs to be compatible with the IIsi!
IMHO, the IIsi was intentionally hobbled as a Low End or, at best, a Mid Market Mac:
__Its RAM config was limited to an odd number by soldering 1MB as Bank A directly onto the Mobo.
____The 4 SIMM Slots available for Bank A on the High End Macs IIci and IIfx being excised from the IIsi to "protect" High End $ale$$$$$$!
__Its expansion was limited to an either/or PDS/NuBus choice physically and probably electronically by, ever so slight, changes to the SE/30's PDS.
____This was probably aided by barring implementation of the NuBus signal on PDS Cards for the IIsi, that pin's signal being different on the SE/30.
__Its ROM/Memory Mapping was limited to only FOUR NuBus Slot/Pseudo Slot Addresses. :disapprove:
Thus, the intentional borking of the IIsi's ROM SIMM pinout!
These changes effectively barred its MoBo from being used for an eminently expandable Hackintosh.
However, forward compatibility for increased utility of the IIsi is an entirely different animal!
_______________________________________________________________________________________
I'm waiting to hear which line needs to be cut on the dougg3's IIci ROM SIMM to make it work in the IIsi.
_______________________________________________________________________________________
I'm betting that Apple didn't want either the IIfx or the IIci ROM SIMMs to be compatible with the IIsi!
IMHO, the IIsi was intentionally hobbled as a Low End or, at best, a Mid Market Mac:
__Its RAM config was limited to an odd number by soldering 1MB as Bank A directly onto the Mobo.
____The 4 SIMM Slots available for Bank A on the High End Macs IIci and IIfx being excised from the IIsi to "protect" High End $ale$$$$$$!
__Its expansion was limited to an either/or PDS/NuBus choice physically and probably electronically by, ever so slight, changes to the SE/30's PDS.
____This was probably aided by barring implementation of the NuBus signal on PDS Cards for the IIsi, that pin's signal being different on the SE/30.
__Its ROM/Memory Mapping was limited to only FOUR NuBus Slot/Pseudo Slot Addresses. :disapprove:
Thus, the intentional borking of the IIsi's ROM SIMM pinout!
These changes effectively barred its MoBo from being used for an eminently expandable Hackintosh.