Mystery IC: Allen Bradley 314B102
ard at p850ug1.demon.co.uk
Tue Dec 15 13:12:16 CST 2015
[Printer's Ready signal]
> > Why not? It's all the host really needs to know -- can I send
> > another character or not.
> Well...it can be very nice for the host to report "out of paper"
> differently from "paper jam" differently from "motor or position
> encoder failure" differently from "failed selftest" etc.
True it's nice, but back then such things were often handled by indicators
on the printer itself (possibly even by a flashing combination of indicators,
so that something like On-line, paper-out and 12cpi all flashing together
means 'RAM failed')
OK, the Centronics interface does have a paper-out line that most
printers implemented, but AFAIK if a printer asserted paper-out
then it also asserted busy (or would do when the buffer was full)
so that the host really only _had_ to check for busy.
It is certainly possible to make a parallel printer interface with
7 or 8 data lines, a strobe and a ready line. Only.
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