Mail Archives: djgpp/1998/01/09/05:01:48
From: | Leon Heller <leon AT lfheller DOT demon DOT co DOT uk>
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Newsgroups: | comp.os.msdos.djgpp
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Subject: | Re: Help: read/write from printer port
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Date: | Fri, 9 Jan 1998 09:43:58 +0000
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Organization: | at home
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Distribution: | world
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Message-ID: | <WKLBkDAeFft0EwSB@lfheller.demon.co.uk>
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References: | <01bd1cc1$d4914d00$ab51e0ce AT rhasty>
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NNTP-Posting-Host: | lfheller.demon.co.uk
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MIME-Version: | 1.0
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Lines: | 49
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To: | djgpp AT delorie DOT com
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DJ-Gateway: | from newsgroup comp.os.msdos.djgpp
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In article <01bd1cc1$d4914d00$ab51e0ce AT rhasty>, Richard Hasty
<rhasty AT io DOT com> writes
>
>I'm brand new to DJGPP and I'm trying to write stuff to the printer port.
>I'm running Win95 if that has anything to do with it. I was thinking I'd
>be able to just use "open" and pretend I was writing to a file called LPT1
>or PRN. It does not work as I would have expected though. The code (only a
>few lines) is at the end of the message. It bombs on the write operation.
>
>Is there a better way of doing it? I was thinking of trying to just write
>to the correct memory address.
>I have an old copy of Turbo C v 1.01 and I tried
>poke(0x000,0x0378,1);
>but that didn't work either. If I tried that under plain old dos would it
>work? Do I even have the right address for the parallel port?
>Can I do something equivalent using DJGPP?
>
>I would love to stop asking these questions. Are there any documents,
>books or any other resources for learning about how to do this kind of
>thing? Also, any reccomendations for the beginner in assembly and writing
>TSR programs and using interrupts?
The printer port registers are I/O-mapped, not memory-mapped. The
easiest way to access them is to use the outportb(port, value) and
inportb(port) functions.
Here's a very simple test program which pulses the port O/P lines.
You'll need to link in the pc library with -lpc, when compiling.
#include <stdio.h>
#include <PC.H>
main()
{
for(;;)
{
outportb(0x378,0x00);
outportb(0x378,0xFF);
}
}
Leon
--
Leon Heller: leon AT lfheller DOT demon DOT co DOT uk http://www.lfheller.demon.co.uk
Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424
See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850
DDS system - schematic and software.
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