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Address multiplexing, Ram so-dimm electrical limits, Table 4-2 – Apple iMac User Manual

Page 52

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C H A P T E R 4

RAM Expansion

52

Main RAM Expansion

Address Multiplexing

4

Signals A[0] – A[13] on each RAM SO-DIMM make up a 14-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 computer by size,
configuration, and sizes of row and column addresses.

IMPORTANT

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

RAM SO-DIMM Electrical Limits

4

Each RAM SO-DIMM must not exceed the following maximum current limits
on the +3 V supply:

Table 4-2

Types of DRAM devices

Device size

Device
configuration

Size of
row
address

Size of
column
address

16 Mbits

2M x 4 x 2

11

10

16 Mbits

1M x 8 x 2

11

9

16 Mbits

512K x 16 x 2

11

8

64 Mbits

8M x 4 x 2

13

10

64 Mbits

4M x 4 x 4

12

10

64 Mbits

4M x 8 x 2

13

9

64 Mbits

2M x 8 x 4

12

9

64 Mbits

2M x 16 x 2

13

8

64 Mbits

1M x 16 x 4

12

8

64 Mbits

1M x 32 x 2

13

7

64 Mbits

512K x 32 x 4

12

7