Input thru printer port

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Article #4732

#4732

From: Edgar Schwietzke
Date: Wed, 11 Oct 1989 07:10

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Several hardware expansions for the 1040 ST are designed to be accessed thru
the printer (parallel) port configured to act as an input port.
For example, the sound sampler which I purchased recently, directly feeds its
(TTL compatible, non-open-collector) outputs to the printer port.

Since the printer port is switched to OUTPUT mode during system initialization,
there is a good chance that the port lines are driven by two opposite voltage
levels, isn't it?
I'm not familiar with the electrical details, but isn't there the risk of
damaging the soundchip?

I've been using the sampler without any problems so far. Nevertheless,
I would like to know what's going on ...

I'd appreciate any comments and further information on this subject.

Edgar Schwietzke
Research Institute of Discrete Mathematics
University of Bonn
West Germany

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From: SCHWIETZ@DBNUOR1.BITNET (Edgar Schwietzke)
Newsgroups: comp.sys.atari.st
Subject: Input thru printer port
Message-ID: <8910110710.AA27097@ucbvax.Berkeley.EDU>
Date: 11 Oct 89 07:10:47 GMT
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X-Unparsable-Date: Tue, 10 Oct 1989 13:12:15 MEZ