Color Computer 2
Same chipset as the CoCo 1, with 4164 DRAM and a bigger ROM.
Open the Color Computer 2 in Retro Bench- Also
- CoCo 2
- Year
- 1983
- CPU
- 6809E @ 0.89 MHz
- RAM
- 16 to 64 KB (4164 DRAM)
- ROM
- Color BASIC mask ROM, 16 KB total on the sheet
- Video
- MC6847 VDG: 32 × 16 text, PMODE hi-res, 9 colors
- Sound
- 6-bit DAC (U3) and single-bit sound via the $FF20 PIA (U2)
- OS
- Color BASIC (E and D layers add Extended and Disk)
Chips
| Chip | Where | Role |
|---|---|---|
| MC6809E microprocessor | Main CPU, 8-bit with 16-bit registers. Same CPU in every CoCo and in the Dragon 32 and 64. | |
| MC6847 video display generator | Text, semigraphics and color video from screen RAM. Used in the CoCo 1 and 2, the MC-10 and the Dragon 32 and 64. | |
| MC6883 synchronous address multiplexer | Makes all clocks from the 14.31818 MHz crystal, the DRAM strobes and address multiplex, and the device selects. Used in the CoCo 1 and 2 and the Dragon 32 and 64. | |
| MC6821 peripheral interface adapter | U7 ($FF00, keyboard) / U2 ($FF20, sound, cassette, RS-232) | Two 8-bit parallel ports with handshake lines. |
| 4164 DRAM 64K×1 | Main RAM (8 chips = 64 KB) | |
| Color BASIC mask ROM | Color BASIC ROM, 8 KB on the CoCo 1, 16 KB total on the CoCo 2 per the sheet. |
Ports and connectors
- Cartridge slot (J6), 40-pin card-edge socket UNVERIFIED
- Joystick ports (J1, J2), DIN socket, 5 pins used (6-pin shell)
- Cassette (J4), 5-pin DIN socket (180°)
- Serial I/O (J3), 4-pin DIN socket
- RF out, Phono (RCA) jack UNVERIFIED
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | 4.75–5.25 V | 6809E pin 7; SAM pin 40; R2 (U1 end) |
| Raw negative | Negative DC | SALT pin 15 |
Symptoms
- No boot: check 6809E, SAM, Color BASIC ROM
- No or bad video: check VDG, SAM
- Dead keys: check 6821 PIA
- No sound or tape: check 6821 PIA
- RAM errors or wrong memory size: check 4164