Re: Foolish Me...
> > Here's the beginning, with the
> > first part of the brightness command.
> > IO: 0x0020 (1 bytes) to port 0x37a
> > IO: 0x0075 (1 bytes) to port 0x378
> > IO: read from port 0x378, res = 0x0075
> Note how they're setting the port to input mode, then they're
> outputting a known value to the output port? I'm pretty sure that
> they're doing this to see if the parallel port is bidirectional. I
> suspect that, if you read back something *other* than 0x75, that the
> port is bidirectional. Anybody have a bidirectional parallel port to
> test this theory?
It's correct. My laptop has the bidirectional/spp/ecp/epp stuff in
it that can be set by the bios on boot. I've also got a book that
states that if you can read back what you wrote to the port, then
it's a non-bidirectional port, and if you read back something different
than what you wrote, then it's bi-directional.
Thomas Davis | Internet: Thomas.Davis@mnscorp.com
Systems Consultant | Snail Mail: Suite 528
Midwest Network Solutions Corp. | 1941 South 42nd Street
(402) 346-7687 | Omaha, NE 68105-2939