Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!mailrus!ames!oliveb!tymix!antares!jms
From: jms@antares.UUCP (joe smith)
Newsgroups: comp.sys.amiga
Subject: Re: amiga parallel lines?
Summary: 4 I/O pins via mouse/joystick ports
Message-ID: <220@antares.UUCP>
Date: 24 Oct 88 07:32:40 GMT
References: <4070@phoenix.Princeton.EDU>
Reply-To: jms@antares.UUCP (joe smith)
Followup-To: comp.sys.amiga.tech
Organization: Tymnet QSATS, San Jose CA
Lines: 21

In article <4070@phoenix.Princeton.EDU> diradin@phoenix.Princeton.EDU (Dean I Radin) writes:
>Question: Does the Amiga provide three other output lines controllable
>    by software? Perhaps some of the game or mouse port pins?

Locate a copy of the Amiga Hardware Reference Manual and check out the chapter
on "Interface Hardware".  Table 8-5 shows the bits used in the POTGO register.
It says: "Instead of using the pot pins as variable-resistive inputs, you can
use these pins as a four-bit input/output port.  This provides you with the
equivalent of two additional pins on each of the two controller ports for
general purpose I/O".

I sent a letter to Steve Ciarcia with this information after he stated
(wrongly) that the pins on that A500 joystick connector could not be used
for output.  Note that getting 2 bits is easy - use the joystick connector.
With a break-out cable, it is possible to get the 3rd bit and still have
use of the two-button mouse.
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