Developer Documentation
   

RAM Addressing

Signals A[0] - A[12] and BA[0] - BA[1] on each RAM DIMM make up a 15-bit multiplexed address bus that can support several different types of SDRAM devices. Table 4-2 lists the types of devices that can be used in the iMac by size, configuration, and sizes of row and column addresses.

IMPORTANT

The iMac supports only the types of SDRAM devices listed in Table 4-2 . Other types of DRAM devices should not be used with this computer.

 

Table 4-2   Address multiplexing modes for SDRAM devices  

Device size

Device
configuration

Size of row
address

Size of column
address

64 Mbits 4 M x 8 x 2 13 9
64 Mbits 2 M x 8 x 4 12 9
64 Mbits 2 M x 16 x 2 13 8
64 Mbits 2 M x 16 x 2 11 10
64 Mbits 1 M x 16 x 4 12 8
64 Mbits 1 M x 32 x 2 11 9
64 Mbits 512 K x 32 x 4 11 8
128 Mbits 8 M x 8 x 2 13 10
128 Mbits 4 M x 8 x 4 12 10
128 Mbits 4 M x 16 x 2 13 9
128 Mbits 2 M x 16 x 4 12 9
128 Mbits 2 M x 32 x 2 13 8
128 Mbits 1 M x 32 x 4 12 8
256 Mbits 8 M x 8 x 4 13 10
256 Mbits 4 M x 16 x 4 13 9
256 Mbits 2 M x 32 x 4 13 8


© 2000 Apple Computer, Inc. – (Last Updated 01 Aug 00)