Broadcast Operation - IBM 2740-1 System Reference Manual

Communication terminal

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Table Of Contents

Table of Contents

• P ress the Bid key. This transmits a (§) signal

to the other terminal on the line (Figures 5

6).

and

Upon receipt of the

ceiving terminal automatically switches to r e

ceive status provided the terminal was originally

in standby status. This change to receive status

causes the keyboard to remain locked and the ter

minal motor to be turned on. If this terminal is

operating in local mode or is not in standby status

when the (B) signal is received, an audible alarm

is automatically sounded at the terminal.

Once the initiating terminal acquires the line

through use of the Bid key, it automatically

switches to transm it status. In conjunction with

this, the Transmit light is turned on, the key

board is unlocked to permit the transmission of

text, and the terminal motor is turned on. This

terminal can now transmit a message (or mes

sages) of any length and retain control of the line

until it signals an End-of-Transm ission (EOT).

• P ress the EOT key.

This transmits an EOT (5)

signal to the receiving terminal. Both terminals

(the transmitting, as well as receiving) switch

to a standby status.

The Standby light at both

terminals is turned on, the keyboards are locked

(except for the Bid key and EOT key), and both

terminal motors are turned off.

Receive

The initial requirement for this terminal is that it

be in standby status. In order to have Status, the

terminal and data set must have power supplied, and

the terminal must be in communicate mode with

paper present in the typewriter.

Terminal

NON-.SWITCHED

LINE

Terminal

or Multiplexor

Figure 5.

Point-to-Point Operation (No Special Features)

1 2

(B)

signal, the re

Bid Key

EOT Key

Text

Bid Key

from

Multiplexor Multiplexor

(B)

• Receipt of the

signal switches this terminal

to receive status (Receive light on, keyboard

locked, and motor turned on). The terminal r e

mains in this status until an EOT signal is r e

ceived (see Figures 5 and 6). However, if this

terminal runs out of paper while receiving, or

drops status for any other reason, it switches to

a no status condition (all status lights off, key

board locked, and still in communicate mode).

Until this condition is corrected (by inserting

paper or deactivating the paper presence contact)

and the line connection is re-established, the

terminal is unable to receive any further trans

missions.

Thus, a procedural requirement pro

viding for message retransm ission when this

occurs should be established for each system.

• Receipt of the EOT signal switches this terminal

to standby status (Standby light on, keyboard

remains locked except for the Bid and EOT keys,

and the terminal motor is turned off).

• If this terminal is in the local mode or is in

communicate mode but out of paper when the

signal is received, an alarm sounds at this ter

minal.

The operator should now switch to the

communicate mode (by positioning the

Communicate/Local key to Com), or insert paper

(or deactivate the paper-presence contact).

Message reception is not possible until this is

accomplished.