Hi Andrew,

> As far as I can tell, PCI parallel port cards do not work under FreeDOS.

Who said that?

> Is that true? Does anyone have any guidance on getting PCI parallel
> ports to work under FreeDOS?

PCI cards are highly configurable, but they can also provide
ordinary and very much ISA compatible resources. Yet most on-
board printer ports are in the ISA subsystem. Which still
exists, as a part of some chip there, even without ISA slots.

You can expect problems if you try to do ISA style DMA to or
from the printer port, but if you use BIOS functions, things
should be okay. DMA is more or less the only compatibility
problem between PCI and ISA. You can also have problems if
arbitrary IRQ numbers are assigned to your "should use known
IRQ number X" ISA device by a PnP BIOS or OS which can be
in the mood to do that, too. Sometimes IRQ 5 or 7 (printer
port ones) are not even on the PnP PCI IRQ choice list. Then your
programs will have to use whichever other IRQ number you get,
if they use IRQ at all for the printer port. Or you will have
to write a wrapper which calls the expected IRQ 5/7 handler
whenever the actual PCI IRQ of your card is triggered. That
would be a really small piece of software :-).


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