Mac IIfx Address Space

 

Below is the memory map of the Input/Output of the Macintosh IIfx. Noramally, a 32 bit processor can access up to 4 gigabytes of memory, but the IIfx can only physically hold 128 megs of memory. In reality, since the IIfx the only Macintosh that uses 64 pin SIMMs, the number is far less to maybe around 64 megs.

Macintosh IIfx I/O Space*
Memory Base		Component
0x50040000	0x53FFFFFF	Reserved (Rep. Images)
0x50048000	0x5003FFFF	Reserved
0x50026000	0x50027FFF	Expansion 5
0x50024000	0x50025FFF	Expansion 4
0x50022000	0x50023FFF	Expansion 3
0x50020000	0x50021FFF	Expansion 2
0x5002E000	0x5002EFFF	Expansion 1
0x5001C000	0x5001DFFF	Expansion 0
0x5001A000	0x5001BFFF	OSS Local I/O
0x50018000	0x50019FFF	BIU
0x50016000	0x50017FFF	ADB
0x50014000	0x50015FFF	Reserved
0x50012000	0x50013FFF	IOP (SWIM)
0x50010000	0x50011FFF	Sound
0x5000E000	0x5000FFFF	Alt. SCSI (Hsk)
0x5000C000	0x5000DFFF	Alt. SCSI (DMA)
0x5000A000	0x5000BFFF	Alternate SCSI
0x50008000	0x50009FFF	SCSI DMA
0x50006000	0x50007FFF	Reserved
0x50004000	0x50005FFF	IOP (SCC)
0x50002000	0x50003FFF	Clock
0x50000000	0x50001FFF	VIA

* Information gathered from Guide to Macintosh Family Hardware.

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