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HPIIISi TWINAX CARD
Appendix C: Parallel-Port Pinouts
Table C-1 shows the pinouts for the parallel printer connector on the
HPIIISi Twinax Card.
DIRECTION is the direction of signal flow from the interface.
RETURN PIN is the twisted-pair return, to be connected at signal ground
level. For the interface wiring, be sure to use twisted-pair cable for each
signal and to complete the connection on the return side. The cable
should be shielded and connected to the chassis of the host computer and
printer.
All interface conditions are based on TTL levels. Both the rise and the fall
times of each signal must be less than 0.2 µsec.
Data transfer is carried out by observing the ACKNLG or BUSY signals.
Data transfer to the printer occurs only after receipt of the ACKNLG signal
or when the BUSY signal is LOW.
Data must be present a minimum of 0.5 µsec before and after a minimum
of 0.5 µsec STROBE pulse. BUSY goes high before the end of the STROBE
signal and remains high until the end of an ACKNLG pulse of 0.5 µsec.
