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From: corwin@ghoti.lcs.mit.edu (Jonathan L. Coburn)
Newsgroups: sci.electronics
Subject: Re: A/D converter ==> PC parallel port?
Message-ID: <1990Dec29.014058.6072@mintaka.lcs.mit.edu>
Date: 29 Dec 90 01:40:58 GMT
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Although the IBMPC parallel port is not designed to be bidirectional,
it can read what it just wrote back out the port.  The way it does
this is by sampling the output latches on the data lines.  Therefore,
if you first write a 0 to the port and then put your data on the
lines and do a read, you will get the data you want.  You have to
be careful not to pull or push too much current when you do this, but
I have done it and it does work, kludgy though it may be.

corwin