IBM 1 Series - Teletypewriter Adapter Design Considerations; Teletypewriter Device Information; Cable Connection to the Teletypewriter Adapter

Teletypewriter Adapter Design Considerations
Teletypewriter Device Information
The teletypewriter should be configured for full-duplex operation and a
20-mA current loop prior to installation. Teletype* Models ASR 33, ASR
35, or KSR 33 are normally shipped from the factory wired for
half-duplex, 60 mA, and even parity.
Either the isolated contact sense input or the nonisolated contact sense
input, with input selection code equal to all 0’s, must be used for
connection of the ASR 33/35.
Either the current driver (current=mark output) or the solid-state switch
(closed=data mark output) must be used for the ASR 33/35.
If the system is powered down, the output driver goes to a data space
condition, causing the device to “‘chatter’’ if it is in “line mode.”’
Consequently, the ASR 33/35 should be turned off or put in “‘local mode’”’
if the system is powered down. However, no damage to the device results
if it is left in line mode, just unnecessary wear.
Also, if the cable is disconnected while the ASR 33/35 is in line mode, the
device can chatter.
During an IPL operation, the ASR 33/35 should be placed in line mode
prior to pressing the Load key on the processor console.
Cable Connection to the Teletypewriter Adapter
EIA
4-30
GA34-0033
The tables in the following sections indicate how pins on the top-card
connector should be connected to pins on the attached device.
The communications power supply feature furnishes +12 volts. This
feature is a prerequisite for any card file (except the 4953-A processor) in
which the teletypewriter (TTY) adapter is installed if the adapter sends
EIA output levels to the device. However, the 12-volt supply is not
required to only receive EIA levels. The connections for EIA are as
follows:
Series/1 TTY card connector Device connector
A4 EIA received data in EIA transmitted data
A6 Data terminal ready Received line signal
detector
BS Signal ground Signal ground
B6 EIA transmitted data EIA received data—connect
request-to-send to
clear-to-send;
connect data terminal
ready to data set ready
Note that two different wrap connectors may be required at the customer
device cable connector: (1) request-to-send to clear-to-send, and (2) ‘data
terminal ready’ to ‘data set ready.’ Connector pin A6 is ‘EIA data terminal
ready,’ and is a logical 1 when power is on in the teletypewriter adapter.
This interface requires a shielded 3-conductor cable; 4-conductor cable if
the ‘EIA data terminal ready’ signal is used.
* Trademark of the Teletype Corporation