This is a Version B-3 PCB produced in 1986. This motherboard is the predecessor of the later Version E short boards. The biggest difference from the older long boards is the use of two 32 kByte RAM chips (41464) instead of eight 8 kByte RAM IC’s. The Assy 250466 motherboard came with the highly acclaimed MOS 6569R5 VIC-II chip and the enhanced SID chip (MOS 6581R4AR) with ‘Advanced Resonance’.
All electrolytic capacitors and voltage regulators have been exchanged with new ones as described in the C64 Capacitor Mod (link).
The machine has the highly acclaimed VIC-II chip (MOS 6569R5) with very few artifacts (vertical lines and checkerboard pattern artifacts).
The machine has the SID chip called MOS 6581R4AR for ‘Advanced Resonance’ at U18.
The two RAM chips with 32 kByte RAM eash located at U9 and U10.
All major chips were made in 1986 including the CIA chips (MOS 6526 at U1 & U2) and the PLA chip (MOS 906114-01 at U17)…
Capacitor C38 (51 pF) has been replaced by a 4.7 nF one to make the RESTORE key work like all the other keys as described in the C64 RESTORE Key Mod (link).
The machine came with a metal shield which functions as a heatsink for all the major chips.
The outside of the case:
Notice the label does not say ‘C64C’ eventhough the cases are identical.
The keyboard is, in lack of a better phrase, the ‘Old Style Commodore 64C’ version with prints on the front of the keys like on the breadboxes (but the plastic is white instead of greyish/brownish)
The original cardboard box the machine came in:
The power LED color is red.
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