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Address Multiplexing

Signals A[0] - A[12] and BA[0] - BA[1] on each RAM SO-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 iBook by size, configuration, and sizes of row, column, and bank addresses.

IMPORTANT

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

Table 4-2  Types of DRAM devices

Device
size

Device
configuration

Row
address
bits

Column
address
bits

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

The use of 8x4 device configurations leads to excessive loading and so is not recommended; see RAM SO-DIMM Electrical Limits.


© 2000 Apple Computer, Inc. – (Last Updated 07 Sep 00)