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dirty contacts in the keyboard?
dirty contacts in the keyboard?
Nope. This is consistent for me.
If I type:
... I am unable to type "?" with the Left Shift key. However if I type:
...The Left Shift key works fine.
Would you help me confirm this?
... I wonder if its an obscure problem with one of my chips.
QuoteNope. This is consistent for me.
what makes you so sure? if you hit ? a few times, do some of them appear?
QuoteI wonder if its an obscure problem with one of my chips.
that would be very odd, if there is a problem with the CIA ports, usually an entire row (or column) of key would be affected.
however, you can test it easily - just swap the two CIAs (6526) against each other. CIA1 is for the keyboard, if it really is the problem, they keyboard should work after the swap, but now you have problems with loading from disk 
Please also see if the shift-lock key works as expected. It is hard-wired to the left shift key.
Please also see if the shift-lock key works as expected. It is hard-wired to the left shift key.
I confirmed that the Shift Lock key has the same behavior I described.
what makes you so sure? if you hit ? a few times, do some of them appear?
I am certain because 100% of the time "?" does not appear under the conditions I described. Again, once I type other characters, then type "?", 100% of the time it appears.
and no other keys are affected? is it only the questionmark that behaves odd with shift? i'd expect any other key showing the same problem (and i still think its a contact problem)
Did you swap the CIAs against each other to check if the problem persists?
and no other keys are affected? is it only the questionmark that behaves odd with shift? i'd expect any other key showing the same problem (and i still think its a contact problem)
Did you swap the CIAs against each other to check if the problem persists?
I have noticed the Cursor Keys and both affected this way as well. I have yet to try the CIA swap yet. I will update when I do.
Have you/someone on your team tested my issue on their own C64R MKII ?
i have used my MK2 quite a bit and i can assure you there is no general problem with the shift keys
i have used my MK2 quite a bit and i can assure you there is no general problem with the shift keys
Haha, I meant no offense!
OK, so swapping the CIA chips fixed the problem! I would love to know WHY though. But for now, I just want to say THANK YOU! This issue was quite annoying.
I wonder what odd behavior I can expect next from the semi-faulty CIA I have...
OK - so the one that was CIA1 before (and is CIA2 now) is the faulty one, you should replace it (and expect other problems if you dont do it)
as to the WHY - the CIAs are the C64s I/O chips, they are connected to various peripherials, for the most part the keyboard, the joysticks and the IEC bus (drives). you can look up the details here: CIA1 Port A CIA1 Port B CIA2 Port A CIA1 Port B.
now, to find out what kind of odd side effects you might expect, look at the keyboard matrix. the left shift key is in the 7th row (bit1 of port a) and the first column (bit 7 of port b). first of all you want to find out which of these is actually defective - for that try all keys of the respective row or column - all of them should show the odd behaviour you have observed with shift. (if that is not the case, try the row/column that has the ? key in it). once you found that out you can look up what these bits are connected to by looking at the tables above - maybe you are lucky and its one of the lines that goes to the userport (rs232), then you could keep using the broken CIA as CIA2 (if you are not using the userport that is). in all other cases you will see misbehaviour, either problems with the IEC bus, or graphics corruption in some programs.
OK - so the one that was CIA1 before (and is CIA2 now) is the faulty one, you should replace it (and expect other problems if you dont do it)
as to the WHY - the CIAs are the C64s I/O chips, they are connected to various peripherials, for the most part the keyboard, the joysticks and the IEC bus (drives). you can look up the details here: CIA1 Port A CIA1 Port B CIA2 Port A CIA1 Port B.
now, to find out what kind of odd side effects you might expect, look at the keyboard matrix. the left shift key is in the 7th row (bit1 of port a) and the first column (bit 7 of port b). first of all you want to find out which of these is actually defective - for that try all keys of the respective row or column - all of them should show the odd behaviour you have observed with shift. (if that is not the case, try the row/column that has the ? key in it). once you found that out you can look up what these bits are connected to by looking at the tables above - maybe you are lucky and its one of the lines that goes to the userport (rs232), then you could keep using the broken CIA as CIA2 (if you are not using the userport that is). in all other cases you will see misbehaviour, either problems with the IEC bus, or graphics corruption in some programs.
Thank you! I think it would probably best to just use different CIA. I have one spare of the 6XXX CIA. Can I drop that one in with my 8XXX CIA?
yes, you can use 6526 or 8521
The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.
