C64 Assembly 250425

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

Specs

  • 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)

Schematics

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

Capacitor List

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   -  10uf    -  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.

IC List

PCB ID Chip ID Notes
U1 6526 CIA 1
U2 6526 CIA 2
U3 2364 ROM - Basic
U4 2364 ROM - Kernal
U5 2332 ROM - Char
U6 2114L-30 SRAM
U7 6510 Processor
U8 7406/7416 Logic NOT
PCB ID Chip ID Notes
U9 4164 DRAM
U10 4164 DRAM
U11 4164 DRAM
U12 4164 DRAM
U13 74LS257 Multiplexor
U14 74LS258 Multiplexor
U15 74LS139 Demultiplexor
U16 4066 Quad Bi-Switch
PCB ID Chip ID Notes
U17 82S100 PLA
U18 6581 SID
U19 6567/6569 VIC-II
U20 LM556 Dual Timer
U21 4164 DRAM
U22 4164 DRAM
U23 4164 DRAM
U24 4164 DRAM
PCB ID Chip ID Notes
U25 74LS257 Multiplexor
U26 74LS373 8 Bit 3-State Latch
U27 74LS08 Logic AND
U28 4066 Quad Bi-Switch
U31 7701/8701 Oscillator

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