moving printer IRQ

[Bill Campbell]

In <1991May29.150702.1691 at icc.com> wdm at icc.com (Bill Mulert) writes:

>On a stock SCO Xenix 2.3.2 system, the line printer driver is
>configured to use IRQ5. In order to free up IRQ5 for additional
>hardware, I need to move the printer driver to IRQ7. When I
>edit the master file, and change the pa entries for vec1 and
>vec2, I get a kernel that fails to boot. I have tried setting
>vec1 to 7 and vec2 to 0, and vec to 0 and vec2 to 7. No deal.

/dev/lp0 and /dev/lp1 are generally configured to IRQ7 and
/dev/lp2 to IRQ5 (at least on every system I've seen).

>Can anyone advise me on how to free up IRQ5 but still have an
>operational printer driver?

The best solution I've come up with is to scrap the parallel
printer ports and hang the printers off a smart multi-port board
using serial->parallel buffers (I use Intellicom 16K buffers).
I've seen (and am currently trying to find a fix for) slow
printing problems under Xenix (2.3.3UFM) with certain printer
port boards.  I've also had problems using the parallel printer
port when printing fax graphics files (slow system and screws up
the VGA board).

Considering the limited intelligence of many DOS targeted
products (mice that must use IRQ2-5...) it makes sense to me to
disable the parallel ports, COM1, and COM2 releasing IRQ3,4,5,7
for other devices.  Hang everything off a smart-port (I use
Specialix).  I have a fax modem, Trailblazer, T1600 modem,
2 printers, and several terminals on one here taking a single
slot in the system and NO IRQs.  The printers are all being
driven at 38,400.

Bill
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