From: robert.desonia@hal9k.ann-arbor.mi.us (Robert Desonia) 
Subject: Re: PC Parallel I/O
Distribution: world
Organization: HAL 9000 BBS, W-NET HQ, Ann Arbor, Michigan, USA
Reply-To: robert.desonia@hal9k.ann-arbor.mi.us (Robert Desonia) 
Lines: 24


R >>>JD> ALL PC parallel ports that are compatable with the IBM standard,
R >>>JD> including the original IBM adaptor, are bi-directional.

NOT ALL PARALLEL PORTS ARE BI-DIRECTIONAL WITHOUT MODIFICATION.

My experience with the standard old zenith parallel port in their 
original 286s proves that.  They had the input direction disactiviated by 
tieing them R/W select line of the circuit to Vcc.  To make it bi ( which 
I did ) I had to modify it by scraping off the trace and solder a jump to 
the proper location.  I thought that this was just lazy on the part of 
Zenith ( they were not Zenith-Bull Group at that time).

-rdd

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