C64 Assembly 250425

• Released in 1984.
• 8-pin board (Reduced Oscillator Circuit).
• Version: B.
• Schematic Number 251469.

• CPU : 6510 @ 1.0227277143 MHz (NTSC) / 0.9852484444 MHz (PAL)
• RAM : 64kB DRAM
• ROM : 20kB ROM Total - 8K BASIC, 8K Kernal, 4K Character
• Graphics : VIC-II
• Sound : SID
• Interfaces : 2 Control Ports (CIA U1), A/V, Datasette Port (CIA U1), Expansion Port, Serial IEC (CIA U2), TV RF, User Port (CIA U2)
• Keyboard : 66 Keys (CIA U1)
• Power Supply : External Transformer (9V AC + 5V DC)

Fig. 1: C64 250425 Mainboard Fig. 2: C64 250425 Layout

The first few production runs of the C64 came with 50v caps (more than likely due to parts availability). Later runs (and their schematics) use 25v caps. Our kits ship with 25v caps.

Cap   -  Value   - Rating - Type
C13   -  10uf    -  25v   - Radial
C19   -  2200uF  -  16v   - Axial
C24   -  22uf    -  25v   - Radial
C88   -  1000uF  -  25v   - Axial
C90   -  470uF   -  25v   - Axial
C91   -  100uF   -  16v   - Radial

C38   -  4.7nf   -   *    - Ceramic

* Replace the 51pf cap with a 4.7nf cap to restore soft-touch RESTORE key function. This is included in our kit.