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Multiplexer
:--ION-
SWITCHED
LINE
r
erminal
i
I
i
i
I
I
I
I
©
T
It..
o
o
R
E
S
S
S
P
It..
C
E
• If bid latch is set by bid key. Otherwise, a
®
response is given
tl")
indicate that terminal daes nat desire access to computer.
r-
Text
@*
©
EOT
Key
Fibrure
:~j.
Station Control. :\Iultiplexer Polling (without Checking Special Feature)
It..
o
A
D
Multiplexer
o
S
R P
E
It..
S
c
©
S E
or
L
R
@)
Text
®c
©,
,
D S
R P
E A
S C
©
S E ,.
--'
NON-
SWITCHED
LINE
Terminal
Text
Text
®
®L
®L
EOB R
R
Key C
C
or
@
. I
)
,
,
{
J J
,
*
If bid latch is set by bid key. Otherwise, a
®
response is given to indicate
that the terminal does not desire access to the computer.
Figllre
:W.
Station Control, l\lultiplexer Polling (with Checking Special Feature)
answerback mode and a
<&
is sent to the multiplexer
indicating that the terminal does not wish to
transmit~
The terminal
IS
then returned to control receive
mode.
After the message. the operator presses theEOT
key to transmit a
©
and to return the terminal to
control recei\'e mode. The terminal is again ready
to be polled or addressed.
IB1\1 2741 Lll\'E CONTROL
Line control becomes effective on the 2741 when the
terminal power switch is turned on and the terminal
mode switch is set to. communicate. The terminal
isthen inatransmit state and a
@
cod~
is sent to
the computer (Figv.res 37 and 38). The operator may
transmit by keying as on a typewriter.
• 30
Terminal transmission ends
whell
the terminal
transmits a
©.
The
©
is transmitted when the
attention key or the carrier return key is pressed.
However, when the carrier
rt:tul~n
key is pressed. a
carrier return code precedes the
©
code. Trans-
mission of the ©code places the terminal in the re-
ceive control mode and the k('yboard is locked waiting
for a
@
code"fromthe computer.
The computer, after receiying the
©
code. trans-
mit~ a
@
code placing the terminal inthe receive
mode. Any valid chara.cter code then received from
the computer causes printing. At the end of trans-
mission, the 'computer senets a
©
code to the termi-
n~.
•
.
The terminal, after receiving the
©
code,
SWitches to transmit mode. The keyboard is unlocked
and the
ter~inal
automatically transmits a
@
code.
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