Introduction - Control Data 1700 Maintenance Manual

CHAPTER II
TELETYPEWRITER CONTROLLER
INTRODUCTION
Two models of teletypewriters are available in the 1700 low-speed system. One
model has been modified to provide a total of three options, these are the Key-
board Send Receive (KSR), Automatic Send Receive (ASR) and modified Automatic
Send Receive. The 1711 option provides a KSR teletypewriter and appropriat~
controller logic. The 1712 provides an ASR teletypewriter and appropriate
controller logic. The 1713 provides a modified ASR teletypewriter and appropriate
controller logic.
The 1711 teletypewriter contains a keyboard and page printer. The unit can
send and receive page-printed information via ordinary telegraph lines. It is
connected to another set and both print whatever is typed from either keyboard.
The KSR features an automatic keyboard lock which senses an open-circuit condition
( a NULL-NULL code) and locks the keyboard at the sending unit. This prevents
further transmission and loss of characters. The lock may also be activated
manually by pressing the BREAK button. The keyboard is unlocked by pressing
the BREAK REL (Break Release) button on the keyboard. Another important feature
of the KSR is that even vertical parity is generated for error detection.
The 1712 teletypewriter consists of a send-receive page printer, a paper tape
punch and a paper tape reader. The ASR has all the capabilities of the KSR
with additional capabilities provided by the paper tape units. The teletypewriter
contains a 5-position Mode Switching Control to the left of the keyboard. An
operator can manually select any of the five following modes:
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