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From: neff@hpvcfs1.HP.COM (Dave Neff)
Newsgroups: comp.sys.atari.st
Subject: DeskJets and Atari Parallel Port
Message-ID: <2150012@hpvcfs1.HP.COM>
Date: 26 Jul 89 18:25:28 GMT
Organization: Hewlett Packard, Vancouver, WA
Lines: 34

I have been conspicuously silent with respect to the Atari ST parallel port
current sink limit and DeskJet/DeskJet+ pullup resistors. 
You see, here's my dilema:  The Atari ST is not officially
supported for use with the DeskJet printers.  This means we have not
tested the printer and our support people will be next to useless in
resolving problems.  They won't tell you to "take a hike, its not supported",
rather our support people simply lack Atari expertise to help with any
significant technical problems.

Furthermore, I am unable to test and verify any of the proposed solutions
to the current limit problem.  Using the 7407 buffer on the data and strobe
lines should work fine, but as an HP representative I cannot say this is the
"HP recommended" solution.  You also could use the serial port at 19.2 K
baud (in most cases this will not hurt performance) but I have been told
by Atari users there are various gotchas when trying to print out the
serial port.  I still fail to understand how the DeskJet+ could damage
an Atari, even though there is one case of anecdotal evidence to the
contrary.  The current limit could result in marginal logic levels
on data and especially strobe, but if the Atari can only sink 1.6ma
thats fine, and if the printer tries to draw more the Atari simply cannot
supply it -- how can this damage the Atari?  If I had an Atari I would
definately buffer the parallel port with the 7407 for logic level
reliability if nothing else.

If you have sent me mail about this problem and I haven't answered
I'm sorry and I hope this posting explains the situation somewhat.
I hope this posting is at least slightly better than nothing.

I have encouraged our support people to make a specific statement on
Atari support especially relating to the current limit on the parallel
port but so far they have not come up with an official position.

Dave Neff
neff@hpvcfs1.HP.COM