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PATHHardware Documentation > Original Power Mac G3 Computers Developer Note


Presence Detect EEPROM

The presence detect serial EEPROM specified in the JEDEC standard is required and must be set properly. Details about the required values for each byte on presence detect EEPROM can be found in sections 4.5.4 and 4.1.2.5 of the JEDEC standard 21-C, release 7 specification.

RAM DIMM Connectors

The RAM DIMM connector accommodates 3.3 volt unbuffered 168-pin SDRAM DIMM cards as defined in the JEDEC specification.

RAM Address Multiplexing

Signals A[0-13] on each SDRAM DIMM make up a 14-bit multiplexed address bus that can support several different types of DRAM devices. Table 4-2 shows the address multiplexing modes used with SDRAM types of DRAM devices. The devices are characterized by their bit dimensions: for example, a 1 M by 16-bit device has 1 M addresses and stores 16 bits at a time.

Table 4-2 Address multiplexing modes for SDRAM devices  

Device size

Device configuration

Number
of banks

Size of row
address

Size of column address

16 Mbits 2 M x 4 x 2 2 11 10
16 Mbits 1 M x 8 x 2 2 11 9
16 Mbits 512K x 16 x 2 2 11 8
64 Mbits 8 M x 4 x 2 2 13 10
64 Mbits 4 M x 4 x 4 4 12 10
64 Mbits 4 M x 8 x 2 2 13 9
64 Mbits 2 M x 8 x 4 4 12 9
64 Mbits 2 M x 16 x 2 2 13 8
64 Mbits 1 M x 16 x 4 4 12 8
64 Mbits 1 M x 32 x 2 2 13 7
64 Mbits 512K x 32 x 4 4 12 7

© 1998 Apple Computer, Inc. - Revised 8/13/98