AT&T 3B2/300 Technical Reference Manual page 406

- - - - - - - - - - - - - - - - - - - - - - - - - - - FUNCTIONAL DESCRIPTION
BACKPLANES
General
The backplane provides connections for power and bus signals between the system board and other
circuit cards that may be in the computer. The backplane also provides for the proper termination of all
bus signals. Because of bus termination, the backplane and system board must always be connected for
the computer to be operational.
The Version 2 backplanes are restricted to I/0 feature cards. The 3B2/300 and 310 computers
backplane (CM193A/B) provide connections for four feature cards. The 3B2/400 computers backplane
(CM194B) provides connections for 12 feature cards.
The Version 3 backplanes provide a connection for the Version 3 system boards. There are also
connections for I/0 feature cards, performance enhancement cards, and memory cards. The CMS 19
series backplanes also have "power only" slots that supply power but no bus connections. The
following table lists the backplane connections for the Version 3 computers.
3B2/500 3B2/600 3B2/700 3B2/1000
(CM520A) (CM519A) (CM519A)
(CM519B)
I/0 Slots 7 12 12 12
Performance
3
Slots
5 5 6
Memory Slots 2 4 4 4
Power Only
0 3 3 2
Slots
FUNCTIONAL DESCRIPTION 3-153