dave3@stretch.MUN.EDU (Dave Fifield) (10/16/89)
I have a problem with my C64 and wish to consult with the collective wisdom of the net in case I'm missing anything. When I turn it on, the cursor immediately begins to move down the screen (as if someone was holding down the return key) and continues ad infinitum. This happens with and without the keyboard connected to the mother board, so I don't suspect the keyboard. A year or so ago, I accidentally touched one of the joysitck ports (port #2) while touching the screen with my other hand causing the internal fuse to blow. This leads me to think that my problem involves the 6526 which controls the port (and the keyboard also?). All advice, fault testing methodology, or just wild speculation is welcome. Thanks in advance, dave -- -- Dave Fifield Dept. of Computer Science dave3@garfield.mun.edu Memorial University of Newfoundland. uunet!garfield!dave3 St. John's, NFLD, Canada
phoenix@ms.uky.edu (R'ykandar Korra'ti) (10/17/89)
/Line eater? What line eater?/ In article <438@stretch.MUN.EDU> dave3@stretch.MUN.EDU (Dave Fifield) writes: >When I turn it on, the cursor immediately begins to move down the screen >(as if someone was holding down the return key) and continues ad infinitum. [Useful Stuff Deleted] >This leads me to think that my problem involves the 6526 which controls the >port (and the keyboard also?). All advice, fault testing methodology, or just >wild speculation is welcome. Dave - The C64 has two CIA chips; if yours are socketed (mine were, but many aren't), pull them both and switch them. If the problem changes, then you're clearly right. If it doesn't; hm. I don't know. It definately sounds like locked bits on the CIA to me. (I had a joystick port "lock" that way, and it was the CIA chip; I think a friend of mine had the same problem you have, and it was again the CIA.) Oh, just our of curiosity; can you still type anything else? Also, if you can, hit the quotation mark (Shift-2) and see what happens. (This is just something "fun" to do, and not related to solving the problem.) If you get graphics symbols, it's not getting a RETURN. (Actually, this would let you figure out which pin on the CIA is locked, but since nobody repairs the little buggers, that's useless information...) - R'ykandar. -- | R'ykandar Korra'ti, Editor, LOW ORBIT | phoenix@ms.uky.edu | CIS 72406,370 | | Elfinkind, Unite! | phoenix@ukma.bitnet | PLink: Skywise | QLink: Bearclaw |
mikemo@opus.uucp (Mike Mo) (10/17/89)
In article <438@stretch.MUN.EDU> dave3@stretch.MUN.EDU (Dave Fifield) writes: >When I turn it on, the cursor immediately begins to move down the screen >(as if someone was holding down the return key) and continues ad infinitum. >This happens with and without the keyboard connected to >the mother board, so I don't suspect the keyboard. A year or so ago, I I have fix a 64C (new version) when it has similar problem, it display "Ready" and begin the next row, until all screen filled with those 24 rows of "Ready" The keyboard doesn't need to be connected to produce this symptom either. I found the 6526 and Basic-Kernel ROM (64C combine two ROM into one ROM) were damaged. Replaced both fixed the problem. Good Luck! Mike Mo, McDonnell Douglas, Tymnet San Jose, California