Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual page 26

INTERFACES
Three interfaces are bidirectional: - serial channel, PLATO
communication, and parallel channel. The terminal can be
configured into several systems or communication networks.
SERIAL CHANNEL INTERFACE
The serial channel interface provides the terminal proces-
sor with an asynchronous, full duplex, bit-serial/
word-serial interface that meets the RS-232-C standard.
The transmitter voltage levels are:
-12.0 V
S
+3.0 V <
Mark or OFF <
-3.0 V
Space or ON
S
+12.0 V
Slew rate is 30 V per microsecond or less.
The receiver voltage levels are:
-22.0
V
< Mark or OFF <
+0.8
V
+0.8
V
~
Undefined
S
+2.0
V
+2.0
V
<
Space or ON S +22.0
V
Open input gives a mark or OFF state (fail-safe condition) •
The send-data and receive-data serial information is asyn-
chronous having the format shown in figure 1-2.
o
I STAR. BIT (SPACE OR HIGH)
®
5,6,7, OR 8 DATA BITS
(1=
MARK OR LOW, 0
=
SPACE OR HIG H)
®
lOR NO PARITY BIT (EVEN OR ODD)
®
1,1.5, OR 2 STOP BITS (MARK OR LOW)
Figure 1-2. Serial Word Format
03342
1-6 82100083 C