15 Dec
2015
15 Dec
'15
11:12 a.m.
[Printer's Ready signal]
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.
-tony
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.