Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!ucselx!bionet!raven.alaska.edu!milton!alfalfa
From: alfalfa@milton.u.washington.edu (Corey Lawson)
Newsgroups: comp.sys.cbm
Subject: Re: Joyless Joyport
Message-ID: <1991May10.031448.1943@milton.u.washington.edu>
Date: 10 May 91 03:14:48 GMT
References: <4186@meaddata.meaddata.com> <1984@ahds.UUCP> <1991May7.185459.2433@cse.uta.edu>
Organization: University of Washington, Seattle
Lines: 39

In article <1991May7.185459.2433@cse.uta.edu> desimone@cse.uta.edu (David DeSimone) writes:
>In article <4186@meaddata.meaddata.com>, johnt@meaddata.com (John Townsend) writes:
>> A friend of mine, who is a big C64/128 fan, has a C64 with a sick joyport.
>> The JOY1 port works fine, but when a working joystick is plugged into JOY2,
>> it will go left and fire, but not go up, down, or right.  The contacts with
>> the port appear to be fine.  Do you have any idea what the problem could be?
>
>The most common cause of this is a frotzed 6526 CIA chip.  This is an
>incredibly common occurence, since Commodore placed the joyports right
>next to the power switch, where static on your fingers can literally fry
>the chip directly.  I recommend leaving joysticks plugged into both
>ports at all times, to avoid this problem.  If you're lucky, all you'll
>lose is joystick functionality.  The 6526's control almost every
>function on your computer, so if you zap one completely, your computer
>won't work at all.
>
>Open up your computer, if you want, and find the two chips labelled with
>a "6526" number somewhere on them.  If these two chips are soldered down
>(ie, you can't remove them), then you're sunk - take it to a repair
>shop.  If they are socketed, you can try mail-ordering a chip and
>sticking it in yourself.  If you've done all that, you are a qualified
>Commodore service person.  :)
>
>-- 
>David DeSimone, aka "Fuzzy Fox" on some networks.          /!/!
>INET:    an207@cleveland.freenet.edu                      /  ..
>Q-Link:  Fuzzy Fox                                        /   --*
>Quote:   "Foxes are people too!  And vice versa."         /  ---

Perhaps the connectors for the joyport are fuzzed on the board.  If
the CIA chip (what a name for a chip...) were fuzzed, then things
would seem to be going weird.  But, since the computer still seems to
be working ok, I'd say that the problem is between the CIA and the
joystick port.  Maybe before checking out the CIA you should get a
tester and see if current flows through the pins in question...use a high
impedence probe...

-corey lawson
alfalfa@milton.u.washington.edu