IBM Series 1 User Manual page 143

output Circuits General Description
Please refer to Figure 4-6. There are four basic types of
outputs available: current driver for data, solid state
swi tch,ITTL for da ta
~
solid sta"te swi tch/TTL for control, and
EIA RS232-C Level. The outputs are selected by utilizing
the appropriate top-card connector pins. All outputs are
driven in parallel so jumperinq
on
the card is not necessary
for selecting an output.
Solid state switches are provided with a resistor and
diode in series tied to +5 volts so that they may be used as
solid state switches or as
TTL
outputs. Any user voltage
greater than 5 volts that is applied to the switch output
isolates the +5 volts from the switch by reverse biasing the
series diode.
Cable Length
A 6.1m (20 ft) cable is provided
by
IBM to connect the
teletypewriter adapter to a teletypewriter device
or a
functionally equivalent I/O device. Por I/O devices
attached to the teletypewriter adapter by either the TTL
interface or the EIA signal level interface, 6.1m (20 ft) is
the maximum permissible cable length. For devices attached
to the teletypewriter adapter
by
the current loop interface,
distances significantly greater than 6.1m (20 tt) can be
achieved but the maximum distance achievable depends upon
cable type, electrical environment, and device data rate.
4-20 GA34-0033
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