Asynchronous Terminals and Printer Processes Programming Manual

PRINTER PROGRAMMING CONSIDERATIONS
Transmit Pause (TPAUSE)
For direct connections (no modems), jumper the DTR line from the
printer (usually pin 20) to the host's secondary received line
signal detector (SCF, pin 12).
For the model 5508, jumper pin 18 (buffer status) to pin 12 of
the host for TPAUSE operation.
For the model 5520, jumper pins 11 and 19 (busy) to pin 12 on the
host to indicate that the 5520 is busy or the buffer is three-
quarters full.
Transmit Pause (TPAUSE)
ATP6100 and SERIALPRINTPROCESS can support EIA printers with
the transmit pause (TPAUSE) feature. With TPAUSE enabled,
the controller monitors the incoming SCSD (pin 12) signal to
determine whether or not the printer is ready. Use the TPAUSE
and DELAYTIME SYSGEN modifiers to select TPAUSE flow control.
The polarity of the incoming TPAUSE signal is defined as follows:
TPAUSE not busy = TPAUSE signal in the = send data
off or logic 0 state
TPAUSE busy = TPAUSE signal in the = do not
on or logic 1 state send data
TPAUSE busy indicates that the printer's buffer has reached
the high-water mark, is out of paper, off line, or otherwise
not ready. The controller should not send any more data.
Conversely, TPAUSE not busy indicates that the buffer has reached
the low-water mark and the controller can once again send data.
Immediately upon detecting TPAUSE busy, the controller halts data
transmission, and the I/O process activates a delay timer. If
the amount of time specified by the DELAYTIME SYSGEN modifier
elapses before TPAUSE becomes not busy, a timeout occurs, and the
I/O operation terminates.
Reverse Channel (RC)
ATP6100 and SERIALPRINTPROCESS can support EIA printers with the
reverse channel (RC) feature. With RC enabled, the I/O process
monitors the incoming SCSD (pin 12) signal to determine whether
or not the printer is ready. The CLIP4 does not support reverse
channel flow control.
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