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Transmit (Normal)
Transmit
(Optional)
Reports
Malfunction (MR)
Line Dis connect
Report (LDR)
Ring (RR)
70/715 Parallel Buffer
• The buffer executes a TC and responds to a CCM SEL with RDY. A bit
is received from the CCM on the Datalead and shifted into a registero The
least significant bit is shifted first (see figure 1). When a complete charac-
ter (eight bits) is accumulated, RDY is inhibitedo At PT the character is
shifted, via the Address (A) lead, to the VRU. The shifting is under control
of the VRU, which supplies the necessary shift pulses. The least significant
bit is shifted first. When WT goes off, the register is reset and RDY is
enabled. Thereafter, a character is sent to the VRU every Word Time (WT).
After receiving TERC and the last bit, the buffer inhibits RDY and termi-
nates as previously indicated.
Note:
This section applies to operation with a Video Response Unit (VRU)o
• The buffer executes a TC and responds to a CCM SEL with RDY. A bit is
received from the CCM on the Data lead and shifted into the first state
(position 7 in figure 1) of the register, RDY is then inhibited for 10ms. A
1 bit in this position of the register causes Answer Back Control A to be
turned on. It remains on as long as
l'
s are being shifted to the buffer. After
receiving TERC and the last bit, the buffer inhibits RDY and terminates as
previously indicated.
Note:
This section applies when a Voice Response Unit (VRU) is not employed.
• The Report signals to the CCM are encoded by the buffer to show the
following conditions:
Malfunction (MR)
Error (ER)
End and Error (EER)
Ring (RR)
END
Line Disconnect Report (LDR)
• When a Transmit Command (TC) is present andprior to END, the buffer
indicates a VRU failure (DOP) to the CCM via a Malfunction Report (MR)D
After an MR, the buffer drops the command which was present as it does
for a Termination (TERC) as previously indicated and is conditioned to
accept a new command.
• When a TC or an RC is present, and prior to END, the buffer indicates a
disconnect condition to the CCM via an LDRo An LDR is caused by loss of
DSR during RC or absence or loss during TC
o
If disconnect and malfunction conditions occur simultaneously only the
MR is indicated to the CCM.
• The buffer is conditioned to detect and RI signal from the data set after a
DISC. While in the quiescent state, the buffer reports Ring once per RI
signal from the data set.
4-13
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