AT&T 3B2/300 Technical Reference Manual page 411

FUNCTIONAL D E S C R I P T I O N - - - - - - - - - - - - - - - - - - - - - - - - - - -
CM519A Backplane Board
The CM519A is a 24-slot backplane board. The system board plugs into the middle of the
backplane board. There are 12 I/0 slots above the system board to hold a maximum of either 6
double-wide or 12 single-width feature cards. There are 12 performance slots underneath the system
board consisting of 4 memory, 4 buffered microbus (for MPE cards), 1 VCACHE, and 3 power only
connectors. Figure 3-50 shows the functional diagram of the CM519A Backplane. Exact signal and
pinout information is provided in Appendix B.
Power and ground (+5 volt, +12 volt, -12 volt, and GRD) for the feature cards are supplied from
the power supply via connectors on the backplane. The floppy disk drive is connected directly to the
backplane via a 34-pin connector. The "Power" and "Diagnostic" LEDs and NVRAM battery are also
connected to the backplane.
3-158 TECHNICAL REFERENCE MANUAL