Commodore.ca: The PET, VIC, 128, 64 & More Forum

I recently dusted of my late husband's C64c to see if it still worked, as I figured I might sell it. All the components do the self test, and the power up message shows up in the correct format.When I try to type anything the letters scroll vertically up the screen, in the manner shown below


t
h

e

b
and disappear at the top of the screen. Is this a serious problem,and should I just take it to be recycled, or is there some stupidly simple fix? When he bought it he got a lot of bells and whistle,ie, joy sticks, modem, fast download cartridge,printer, and a couple of other pieces that I have no idea about. It has always been kept in a dry place, so moisture shouldn't be the problem

Hi,

The problem may be related to the 1st CIA (Complex Interface Adapter) chip, which is responsible for
the processing of the keyboard matrix and the joystick signals.
Is the cursor stays in place during typing?
...or could you share a video with us about the phenomenon?

LoneWolf33 wrote:The problem may be related to the 1st CIA (Complex Interface Adapter) chip, which is responsible for
the processing of the keyboard matrix and the joystick signals.

I agree. For example, when there is a not-so-nicely-working joystick attached to the computer, it could affect keypresses.

Writing from the Portland, Oregon area,

the joy sticks aren't connected and the cursor moves from left to right as you type. It would be almost impossible to video the action, as I'm the only one here and although I can walk and chew gum at the same time, I can't type and film at the same time. I am computer savy about newer computers but have no idea what a CIA chip is and where I might find it, or what to do if I did find it. I know they a pron to static electricity problems, so I unplugged every thing and let it sit for 2 days, to no avail. Any other suggestions please.

taxilady wrote:...but have no idea what a CIA chip is and where I might find it, or what to do if I did find it.

The two CIA chips in the C64 are marked on the top of the chip with the number, 6526. If you are lucky, they are socketed, and then with a screwdriver or chip puller, you can pull them out and replace them with working 6526 chips. If they are not socketed (i.e., if they are soldered to the board), then you will have a harder time to replace them (which entails cutting off the legs of the old chips, desoldering out all the through holes on the board for the chips, soldering in sockets, and then plugging in the chips (or if you don't want sockets, then just solder the legs of the 6526 chips into the through holes on the board.))

Writing from the Portland, Oregon area right now,

I don't know what I did but I've stopped the letters from scrolling up the page, but now the cursor just runs across the screen, getting lower and lower as it goes, till it just runs across the bottom. I can make it back up and climb the screen with the cursor keys, but then it just goes back to running across the screen. The letters in words I type have extra spaces in them, because the cursor is going so fast. I think I should just junk it. It seems a shame, since I just found out the computer shop in town has them for sale now. I just don't know if it is worth having them look at it.

taxilady wrote:I don't know what I did but I've stopped the letters from scrolling up the page, but now the cursor just runs across the screen...

Oh, it sounds as if you have a space bar that is stuck (making contact) all the time. Try lifting the space bar up to make it stop.

I think I should just junk it. It seems a shame, since I just found out the computer shop in town has them for sale now. I just don't know if it is worth having them look at it.

Don't junk it. It can be repaired... but does that computer shop know anything about Commodores? If you cannot repair it, it may be worth your while to have it fixed by a Commodore technician, like Ray Carlsen.

Writing from Portland, Oregon right now,

I went to see if the space bar was stuck, and when I turned it on, it was working properly. I put a game disc in and it loaded the game, so it seems as if it is working properly now, though I have no idea why. I guess I shouldn't look a gift horse in the mouth. Now I can advertise it for sale, and hope it keeps working. Thanx for all of your suggestions.
Pat Wells 100 Hundred House, BC