Specifications

CHAPTER 4
Expansion Features
42 RAM DIMMs
This chapter describes the expansion features of the Macintosh Performa 6400 computer:
the RAM expansion slot, the L2 cache expansion slot, the PCI expansion slot, the DAV
connector on the video input module, the communications slot, and the expansion bay
for SCSI devices.
Note
Apple does not support development of third-party cards for the video
input slot, nor does Apple support development of third-party second
level (L2) cache cards, because the L2 cache controller is integrated into
the design of the cache card. ◆
RAM DIMMs 4
The Macintosh Performa 6400 computer has two RAM expansion slots. The RAM
expansion slots accept the 8-byte DIMM (dual inline memory module). As its name
implies, the 8-byte DIMM has a 64-bit-wide data bus.
The mechanical design of the 8-byte DIMM is defined by the MO-161 specification
published by the JEDEC JC-11 committee; its electrical characteristics are defined by the
JEDEC Standard No. 21-C. The 8-byte DIMM connector used in the Macintosh Performa
6400 computer is Burndy Corporation’s part number ELF168E5GC-3Z50 or equivalent.
The minimum bank size supported by the PSX IC is 4 MB and the largest is 32 MB; the
largest DIMM supported is a two-bank DIMM holding 64 MB. Table 4-1 shows the
single-bank DIMM configurations and sizes for a range of DRAM device sizes that are
supported on the Macintosh Performa 6400 computer.
Note
It is possible to use 5 volt EDO (extended data out) memory devices in
the Macintosh Performa 6400, however any added performance
available with EDO devices will not be realized. 3.3 volt EDO DIMM
cards are not supported and should not mechanically fit into the DIMM
connectors on the Macintosh Performa 6400 main logic board. ◆
Table 4-1 Memory sizes and configurations
Device size DIMM configuration DIMM size
Maximum memory with
2 DIMMs installed
4 Mbit 512K by 64 4 MB 16 MB
4 Mbit 1 Mbit by 64 8 MB 24 MB
16 Mbit 1 Mbit by 64 8 MB 24 MB
16 Mbit 2 Mbits by 64 16 MB 40 MB
16 Mbit 4 Mbits by 64 32 MB 72 MB