Today I've been messing up with my C65 stuff, as a result of a break from
work. I would like to share with you some details and questions that have
arised during the process...
Commodore 65 computers, from revision 3 on, use revision 5 of the CPU, the
4510, which is pin-incompatible with previous revisions. Any attempt to swap
this chip with a lower revision will result in a C65 that simply doesn't
boot. 4510R3 and 4510R4 are, instead, interchangeable ( I have both
revisions and tested both succesfully ). The new pin configuration,
unfortunately, while mentioned, is not documented in the manuals.
The manual says that also the VIC-III with revision 7, 4567R7, has a pin
configuration. On a spare Rev 5 board I had a VIC-III chip, which identifies
itself as 390489-03, 4567P. 4567P doesn't sound exactly as 4567R7. I wanted
to understand wether this chip had a R5 layout or an R7 one.
I tested this chip on a working Rev 5 computer and worked perfectly, then on
an incomplete Rev 2A motherboard, with a 4510R4 : the computer booted but
the video output is screwed in 80 coloumns, with four of five coloumns of
flashing garbage showing on the left side of the video output (RGBI ).
I ran some VIC-III tests with the burn-in cartridge, which succeeded on the
Rev 5 motherboard but failed on the Rev 2A once the 80 coloumns were
required. The fact is this Rev 2A motherboard I have was not supposed to
work, and Rev 2A I saw working have some hand made patches which my board is
Unfortunately, I have been unable to test this chip on the Rev 2B computer
that was there, ehm...I was afraid to break the VIC-III removing it from a
working computer, it was so strongly fitted inside the socket and didn't
come out... I pulled a little but the board start to sound as if it was
cracking and, well...I gave up.
The fact is...If the VIC-III with part number 390489-03, aka 4567P, has the
new R7 pinout, the C65 shouldn't boot at all, let alone run and pass
succesfully all the tests in 40 coloumn mode.
I can't do anything but ask around to figure it out wether this 4567P chip
is compatible or not with a Rev 2B. Since I can't test it myself, the
question goes to all those who own a Commodore 65 Revision 2B.
Which is the revision number written on your C65's VIC-III ? Has anybody got
a C65 Rev 2B with a VIC-III w/ p/n 390489-03 ( aka 4567P )installed on it ?