Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsd!sdcsvax!trantor.harris-atd.com!x102c!bbadger
From: bbadger@x102c.harris-atd.com (Badger BA 64810)
Newsgroups: comp.sys.cbm
Subject: Help troubleshooting C64 lockup
Keywords: C64, lockup, troubleshooting
Message-ID: <1661@trantor.harris-atd.com>
Date: 8 Mar 89 22:34:38 GMT
Sender: news@trantor.harris-atd.com
Organization: Harris GISD, Melbourne, FL
Lines: 27

I have a couple of C64's with a similar problem:  when powered up, the display
is blank and the keyboard seems to be locked up.  By flicking the power off 
and on, I can sometimes get ``garbage'' to come up on the screen, so this 
proves that the video is basically sound (i.e., VIC, xtal, etc.).

You can probably get your machine into a similar state by unplugging the 
keyboard from the main board.  The screen remains blank.   I had this sort 
of problem twice before, and replacing the keyboard 6526 (Peripheral 
Interface Chip) did the trick.  The first time this happenend, I remember 
swapping the two 6526's and getting either a keyboard that worked, or a 
disk drive that worked.

Anyway, I bought a new 6526, and that didn't fix it.  I have a total of 5 
chips available and tried all 20 (5*4) combinations in the two spots with 
no luck.  (Of course, the chips themselves are suspect, since 4 of them came
from the two "broken" machines.)

Does anyone familiar with C64 kernel boot-up ROM code know if my suspicions 
about the keyboard interface are reasonable?  That is, if the kbd PIC is bad,
a black screen is displayed because the ROM code will not proceed to the 
point where the VIC is properly enabled.

Don't sweat too long on this one --- I'll probably just buy a new C64 anyway.
Bernard A. Badger Jr.	407/984-6385          |``Use the Source, Luke!''
Secure Computer Products                      |``Get a LIFE!''  -- J.H. Conway
Harris GISD, Melbourne, FL  32902             |Buddy, can you paradigm?
Internet: bbadger%x102c@trantor.harris-atd.com|'s/./&&/' Tom sed expansively.