IBM Series 1 User Manual page 127

The communications power feature ('2010) furnishes ±12 volts
and is a prerequisite for the teletypewriter adapte~ feature
it.
the attached device is connected to either the
non-isolated current loop inte~face or the EIA voltage level
interface. An exception to this is when the teletypewriter
adapter is plugged into a 4953-A Processor, where ±12 volts
is standard on the backpanel.
The communications powe~ feature is
.!!Q!:
a prerequisite
for the teletypewriter adapter
if
the attached device is
connected to either the isolated current loop interface or
the TTL voltage level interface. When the attached device
is connected to the isolated current loop interface, the
user must supply power to drive the transmit and receive
loops. When the attached device is connected to the TTL
interface, normal logic levels presented on the
teletypewriter adapter card are used to drive the transmit
and receive loops.
The teletypewriter adapter card can be plugged into any
I/O position that has +5 volts available at the card slot on
the 4955 or 4953 card files or the I/O expansion card file.
Refer to the prerequisite publications listed in the
"Preface" of this manual.
The teletypewriter adapter is a device adapter designed to
attach OEM devices that operate
as start-stop devices in
full duplex mode over a 4-vire interface (one pair of wires
to transmit data, one pair of wires to receive data). Data
can be transferred in current loop mode, or as either EIA or
TTL signal levels.
The following is a list of different types of devices
commercially available that can be attached to this
interface.
Printer-keyboards
Keyboard-display
Keyboard-display-printer
Printers
Tape cassettes
Tape
Card readers
Badge reade.rs
Plotters
4-4 GA34-0033
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