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

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