Pages

Mac Plus memory map



high memory
address
contents
$EFFFFF
end of VIA space
$E80000
beginning of VIA space
$DFFFFF
end of IWM space
$D00000
beginning of IWM space
$BFFFFF
end of SCC write
$B00000
beginning of SCC write
$9FFFFF
end of SCC read
$900000
beginning of SCC read
$5FFFFF
end of SCSI
$580000
beginning of SCSI
$41FFFF
end of ROM
$400000
beginning of ROM
$3FFFFF
end of RAM for 4MB Mac Plus
$27FFFF
end of RAM for 2.5MB Mac Plus
$1FFFFF
end of RAM for 2MB Mac Plus
$0FFFFF
end of RAM for 1MB Mac Plus
varies
sound buffer
varies
System Error Handler area
varies
main screen (ScrnBase)
varies
MacsBugs (optional)
varies
RAM cache (optional)
varies
Jump Table (A5 relative)
varies
application and QuickDraw globals (A5 relative)
varies
stack (A7)
varies
Application Heap (ApplZone)
$001600
beginning of System Heap (SysZone)
$000E00
beginning of Toolbox A-trap table
$000800
additional low-memory global area
$000400
beginning of OS A-trap table
$000100
beginning of low-memory global area
$000000
beginning of RAM
Motorola 680x0 vectors
low memory