IBM 1 Series - Chapter 4. Teletypewriter Adapter Feature; Introduction

Introduction
The teletypewriter adapter feature (Figure 4-1) is designed primarily to
attach teletypewriter I/O devices to the processor I/O channel. The
adapter may also be used to attach other devices that satisfy the
requirements of the interface. The feature offers signal and bit-rate
Chapter 4. Teletypewriter Adapter Feature
selectability by using the appropriate pins of a 16-pin top-card connector
and by jumpering the pins on the feature card.
The teletypewriter adapter feature has a four-wire interface for data
exchange—two for receive and two for transmit. Operation is full-duplex;
that is, data may be transmitted and received concurrently.
The input options offered are:
Isolated contact sense
— Open circuit=mark (logical 1);
— closed circuit=mark
Nonisolated contact sense
— Open circuit=mark;
— closed circuit=mark
TTL
— Plus level=mark;
— minus level=mark
EIA received data
— Minus level=mark (standard convention) or
— plus level=mark
The output options are:
Solid state switch/TTL
— Closed/minus=mark or
— open/plus=mark
EIA transmitted data
— Minus=mark (standard convention)
Current driver output
— Current=mark;
— no current=mark
Other output lines available are:
EIA data terminal ready (on when +12 volts installed)
Solid-state switch/TTL write control
Solid-state switch/TTL read control
Teletypewriter Adapter Feature
4-1