Texas Instruments 990 Maintenance Manual page 12

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945408-9701
Table 1-1. TTY/EIA Terminal Interface Module Electrical Characteristics
Specification
Peripheral Inputs
Module Outputs
Power (from computer or
expansion chassis)
Transmission Rates Available
Requirement
(EIA Data) -3V to -25V = Logic 1 (Marking)
3V to 25V = Logic 0 (Spacing)
(EIA Control) 3V to 25V = Logic 1 (on)
-3V to -25V = Logic 0 (off)
(TTY) Short Circuit = Logic 1
Open Circuit = Logic 0
(EIA Data) -SV to -11 V =Logic 1
SV to llV =Logic 0
(EIA Control) SV to 11 V = Logic 1
-SV to -11 V = Logic 0
(TTY) 20ma Current Loop = Logic 1
Open Circuit
=
Logic 0
+5Vdc at 0.38A
EIA I
f
I
±12Vdc at 20 mA
nter ace 20 mA
75, 110, 300, 1200, 2400, 4800 and 9600 baud
5 Digital Systems Division