Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual page 107

COMMUNICATION INTERFACE/INTERNAL MODEM
This expansion module interface connects the terminal pro-
cessor to a communication adapter module (modem). The
interface connector is a PC-mounted, 20-pin flat ribbon
cable, CDC t51847500~ the mating connector is CDC #65853405.
Table 4-9 describes the pin assignments of the internal
interface. Figure 4-22 shows the actual wiring of the
PLATO interface signals and expansion module signals. The
signal descriptions are as follows:
• Power and Ground - Power available for the optional
adapter board is:
+5
V -
250 rnA (1.25
W)
+12
V -
100 rnA (1.2W)
-5
V -
150 rnA (0.75 W)
-12
V -
100 rnA (1.2 W)
• DATA/TALK Switch - This switch is on the front panel
of the terminal. Set to TALK, the contacts are
open, and set to DATA, the contacts are closed.
This switch simulates the exclusion key of some
telephone sets.
82100083
B
4-45
I