Point-To-Point Operation-Multiplexer And Terminal - IBM 2740-1 System Reference Manual

mains locked), the Restart light is turned on, and
the audible alarm sounds at the transmitting term i­
nal. The Transmit light will remain on.
The Bid and EOT keys are used the same in this
operation as previously described.
EOB key now permits the transmitting terminal
operator to designate blocks of data by pressing this
key when desired. When the EOB key is pressed,
an LRC comparison occurs automatically following
this action. The transmitting terminal is notified
of the check results by receipt of either a positive
answer, Yes © , or a negative answer, No (
The transmitting terminal is then either available
for further transmissions (Transmit light on), or the
keyboard is locked (with the R estart light and the
Transmit light on). In the second instance, further
transmissions cannot occur until the Restart key is
pressed, turning out the associated light and un­
locking the keyboard.
The line connection is dropped by operating the
Dial Disconnect key at one of the terminals (or if
either terminal runs out of paper). Operating this
key has no effect when the terminal is in transmit
status.
Point-to-Point Operation—Multiplexer and Terminal
When operating point-to-point with a multiplexer,
the 2740 Model 1 terminal operates basically the
same as when operating point-to-point with another
2740 Model 1 terminal. See " Point-to-Point Opera­
tion (Term inal-to-Term inal)" in this section of the
manual.
Terminal A
NON-SW ITCHED
Terminal B
LINE
Terminal C
Figure 7. Broadcast Operation (No Special Features)
14
Transmit
P ress the Bid key. This transmits a
the multiplexer (Figures 5 and 6).
causes the multiplexer to automatically switch to a
However, the
receive status. Once the terminal acquires the line
through use of the Bid key, it automatically switches
to a transmit status. In conjunction with this, the
transmit light is turned on, the keyboard is unlocked
to permit the transmission of text, and the terminal
motor is turned on. The terminal can now transmit
a message (or messages) of any length and retain
) .
n
control of the line until it transmits an EOT © _
signal.
signal to the multiplexer and places the terminal in
a standby status.
is turned on, the keyboard is locked (except for the
Bid key and EOT key), and the motor is turned off.
Receive
The multiplexer initiates a transmission by placing
a
the terminal to switch from a standby status to a
receive status (Figures 5 and 6).
light turns off, the Receive light turns on, the key­
board is locked, and the terminal motor is turned on.
The terminal remains in this status until a (c ) signal
is received from the multiplexer, or until terminal
Bid Key EOT Key
® Text O
P ress the EOT key.
The Standby light at the terminal
(5)
signal on the communication line, which causes
NOTE: One Idle character must follow the 0
terminal motor to attain full speed.
® ©
Bid Key EOT Key
(3) to
signal
This signal
This transmits a ©
The Standby
to enable the
© Text ©
Bi^Key EOT Key