[comp.sys.ibm.pc] Silly question about parallel port reading

goldstein@arecibo.aero.org (02/21/90)

-Message-Text-Follows-

Hi. I'm sure the answer to this is obvious, but I haven't been able to find 
good documentation on it. Please email me directly to prevent irritating 
other users of this group. Thanks!

The problem: transfering data from an obsolete compatible-to-nothing 
computer to my PC compatible. The only ports they have in common is a 
parallel port. Should be easy, then, to read in with my PC from the output 
of the other. Well, it's not. The other machine (UnComp) has d0-d7 hooked up 
directly to the parallel port, and only identifies transmission by pulling 
strobe-bar low when it's sent a byte. It does also observe busy-bar.

My PC compatible should be reading the parallel port by setting bit 5 of the 
parallel control register (at 37A hex) high, and reading the values from 378 
hex. (At least, I think it should.... am I right?)

The problem seems to be that the old UnComp is flipping d0-d7 around 
continuously, and, of course, when it's putting out a high bit on any of 
those when my PC is keeping the line low, I get trouble.

I know that the PC is capable of reading through the parallel port, since I 
tested it with LapLink and it worked beautifully.

How stupid am I being? What am I missing? Any advice?
___Samuel___
_________I_claim_and_accept_sole_responsibility_for_the_above._SjG.____________
<goldstein@aerospace.aero.org> | "I should have been a pair of ragged claws,
<goldstein@arecibo.aero.org>   |  Scuttling across the floors of silent seas."
(213) 336-3592 (9-5, M-F)      |     --   J. Alfred Prufrock (T. S. Eliot)
Thank you!