LPT1 problems

[Fred Cady]

At 02:00 AM 10/26/95 +0000, you wrote:
>I think it is safe to say that LPT1 has been broken since 9.23 or 9.24 at
least.
>Let's put that rumor to rest.  I checked the LPT port pins 1, 17 and 18 and
>there is NO switching on LPT1 at all in 9.26.  LPT2 is fine on 9.26.  I 
>confirmed this with two completely different computers.

LPT1 works for me.  Tested cw keying and band data on LPT1 with version
9.26.  I'll bet the problem/confusion has to do with enhanced
(bidirectional) versus "standard" unidirectional LPT ports.  The original
IBM design, while it had a bidirectional buffer, was only an output port to
the printer because the direction control on the buffer was hardwired to
ground.  I havn't seen any documentation on bidirectional ports (can anybody
give me a reference) but normal practice with bidirectional ports is that
they come up in input mode on reset.  That's the safe way to do it.  In the
enhanced mode there must be a way to control the direction pin on the buffer
and a short little program that goes out and sets that bit before loading CT
would proabably fix the problems.  Anybody got any ideas?

Fred KE7X
Fred Cady (ieefc@msu.oscs.montana.edu)


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