AT&T 3B2/300 Technical Reference Manual page 152

EQUIPMENT D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - -
CM523B 2-Megabyte RAM Card
The CM523B 2-Megabyte RAM Card uses surface mount technology. The card is a multilayer
board containing 88 surface mounted 256K by 1-bit DRAM chips (which includes 24 chips for storing
ECC information) and 5 surface mount memory drivers. Forty-two bypass capacitors are mounted near
the DRAM and memory drivers. The CM523B Card can be used in all models of Version 3
3B2 computers. Connection to the system board is via a 120-pin connector on the backplane. Card
pinout information is provided in Appendix B. The card is 6.5 inches wide by 7.4 inches deep.
Figure 2-35 shows the component layout of the CM523A Card.
7.~"
y
y
0.75"
I\
2
§
120
DDgDoooooo
DEID
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
DDDDDDDD
0 DDDDDDDD
0
Conventional Component Side
l o
c:::J
c:::J
ol
Figure 2-35: CM523B 2-Megabyte, Surface Mounted, RAM Card Layout
2-128 TECHNICAL REFERENCE MANUAL