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From: news@cit-vax.Caltech.Edu (Usenet netnews)
Newsgroups: comp.sys.ibm.pc
Subject: Re: LPT3 support
Message-ID: <1348@cit-vax.Caltech.Edu>
Date: Tue, 16-Dec-86 01:48:47 EST
Article-I.D.: cit-vax.1348
Posted: Tue Dec 16 01:48:47 1986
Date-Received: Wed, 17-Dec-86 04:23:38 EST
References: <133@parcvax.Xerox.COM> <295@ima.UUCP>
Reply-To: tim@tomcat.caltech.edu (Tim Kay)
Distribution: na
Organization: California Institute of Technology
Lines: 19
Summary: Why does the printer interface lose interrupts?

Organization : California Institute of Technology
Keywords: printer interface, interrupts
From: tim@tomcat.Caltech.Edu (Tim Kay)
Path: tomcat!tim

In article <295@ima.UUCP> johnl@ima.UUCP (John R. Levine) writes:
>Due to the poor design of the IBM printer interface, you can't run the printer
>with interrupts -- there's no way to keep from losing the interrupts.  Programs

Could you elaborate on this?  I wrote a printer device driver that had
some buffering.  This can speed up output to the Epson by a factor of
two by overlapping the computation of the next line with the printing
of the current one.  The driver relied on printer interrupts.  It worked
reliably for most applications.  However, occasionally, an interrupt
was lost.  It was rather annoying.
Timothy L. Kay				tim@csvax.caltech.edu
Department of Computer Science
Caltech, 256-80
Pasadena, CA  91125