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Terminate (TERC)
Out of Service
(OS
C)
Call Attendent
(CAC)
Data Transfer
Initial Conditions
Receive
70/715 Parallel Buffer
•
The TERC command conditions the buffer to terminate a transmit,
receive, or auto-call command.
•
The OSC command conditions the data: set to appear out of service or
busy to an incoming calL Upon receipt of an OSC, the buffer turns OS if
DTR is off and responds to a SEL with END.
The buffer is restored to service by a DISC. The buffer automatically
goes out of service if power fails or upon receipt of the Reset signal from
the CCMo
• A CAC command causes the buffer to signal an attendent to take a call.
DTR must be on in order for the command signal to be interpreted as CAC
rather than OSC.
•
Whenever the buffer receives a SEL from the CeM, it responds with
BOP; regardless of command status or line condition. In the absence of a
command, the buffer remains in the condition in which it was placed upon
termination (END) of the previous command.
It
is conditioned to receive a
new commando
Whenever a signal appears on the Reset lead from the C CM, the buffer is
restored to its quiescent condition and the command which was present, if
any, is dropped and OS is turned on. The buffer responds to a subsequent
SEL with BOP, only; until another command is received.
•
The buffer executes an RC as previously indicated. When DP is on, the
buffer is conditioned to gate a bit-parallel character (AI to A4 and BI to
B4) into a register from the data set. The buffer then responds to a CCM
SEL with RDY. The stored character is transferred to the CCM on the Data
lead, one bit at a timeo The least significant bit is transferred first (see
figure4-1)o RDY is inhibited after the most significant bit has been trans-
ferred to the CCM. Additional input data characters are similarly trans-
ferred to the CCMo After a TERC is received, the buffer terminates as
previously indicated.
I I
Data from
X403A Data
I
Set
I
\
"
......
_-.
DatcacfMrom
~l~=:7====6:_==:5:==:4:===3:===2====:1===~O+
__ . .
~
_
PB Register
.
Data to
CCM
-----,
I
I
I
TC ,
ToVRU
Figure 4-1. Parallel Buffer Data Flow
4-12
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