[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. -tony