Newsgroups: comp.sys.amiga.programmer
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!batcomputer!cornell!johnhlee
From: johnhlee@CS.Cornell.EDU (John H. Lee)
Subject: Re: accessing 25 pins p. port
Message-ID: <1991May15.000458.4329@cs.cornell.edu>
Sender: news@cs.cornell.edu (USENET news user)
Nntp-Posting-Host: fulla.cs.cornell.edu
Reply-To: johnhlee@cs.cornell.edu (John H. Lee)
Organization: Cornell Univ. CS Dept, Ithaca NY 14853
References: <91135.001746IERBS02@TECHNION.BITNET>
Date: Wed, 15 May 1991 00:04:58 GMT
Lines: 24

In article <91135.001746IERBS02@TECHNION.BITNET> IERBS02@TECHNION.BITNET writes:
>I have a technical question for which nobody has given me the answer
>yet.    How can I access the 25 pins of the parallel port?
>I would like to be able to take control  of the port  and then read the
>state of each pin (1 or 0) and change it.  I use Aztec C 3.6.

You can't.  Only 11 or so signal pins of the parallel port are
programmable through one of the Amiga's CIA's (Complex Interface Adapters.)
The remaining pins are either hardwired to a non-programmable CIA pin,
ground, +5, or not connected.

You can take control of the parallel port by requesting it through the
operating system.  Open the appropriate CIA resource and allocate only those
CIA control bits and registers that control the parallel port (the CIA also
controls other functions such as the serial port handshaking.)  You can
then program the parallel port as you desire.  The CIA resource details are
given in the version 1.3 (blue cover) Amiga ROM Kernal Manual: Libraries
and Devices, and Amiga ROM Kernal Manual: Autodocs.  Details about
programming the CIA's are in the Amiga Hardware Reference Manual.

-------------------------------------------------------------------------------
The DiskDoctor threatens the crew!  Next time on AmigaDos: The Next Generation.
	John Lee		Internet: johnhlee@cs.cornell.edu
The above opinions are those of the user, and not of this machine.