VIC and CPU substitutions in the C64C board (250469)
                       latest updates or corrections  11-12-2021

     Somehow I ended up with a dozen or more 8564 VIC chips for the "flat" C128.
I decided to see if one could be adapted to work in a C64C motherboard which
normally uses a hard-to-find 8562 IC. It works but of course requires an adapter 
to cross-connect some pins. The 8562 is a 40 pin IC and the 8564 has 48 so some
of its pins are not used and were left open. Note that the 8564 C128 VIC IC does 
not work in earlier C64 boards and I don't know why.
     Another experiment was tried to see if a C128 8502 MPU IC would substitute
for the 8500 in the C64C and it also worked. The photo "CPU & VIC subs.jpg" shows
how they are wired up. Note the added clock pulse delay circuit using a TTL IC. 

     Note: these are just experiments to see if those chips can be substituted. 
I don't know how well they will work in all applications. 

CAUTION: Never try to install an 8562 VIC IC from the 250469 short board into an
earlier C64 board that uses a 6567 VIC. The +12V on pin 13 that is only +5VDC in
the 25469 board will destroy the 8562!!! The install of a 6567 in a C64C short 
board will produce an opening screen but it looks very bad as the two chips are 
not compatible. 

Ray