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RAM Address Multiplexing

Signals A[0-13] on each SDRAM DIMM make up a 14-bit multiplexed address bus that can support several different sizes of SDRAM devices. Table 4-1 shows the address multiplexing modes used with the devices. The devices are characterized by their bit dimensions: for example, a 1 M by 16-bit device addresses 1 M and stores 16 bits at a time.


Table 4-1 Address multiplexing modes for SDRAM DIMMs  

Device size

Device configuration

Size of row address

Size of column address
16 Mbits 2 M x 4 x 2 11 10
16 Mbits 1 M x 8 x 2 11 9
16 Mbits 512K x 16 x 2 11 8
64 Mbits 8 M x 4 x 2 13 10
64 Mbits 4 M x 4 x 4 12 10
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 1 M x 16 x 4 12 8
64 Mbits 1 M x 32 x 2 13 8
64 Mbits 512K x 32 x 4 12 8
128 Mbits 16 M x 8 x 2 13 10
128 Mbits 16 M x 8 x 4 12 10
128 Mbits 8 M x 16 x 2 13 9
128 Mbits 8 M x 16 x 4 12 9
128 Mbits 4M x 32 x 2 13 8
128 Mbits 4M x 32 x 4 12 8
\xA9 1998 Apple Computer, Inc. — (Last Updated 5 Jan 99)

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