Color Computer 3
The GIME TCC1014 custom chip replaces the VDG and SAM.
Open the Color Computer 3 in Retro Bench- Also
- CoCo 3
- Year
- 1986
- CPU
- 6809E @ 0.89 or 1.79 MHz
- RAM
- 128 or 512 KB (41256 / 4464 DRAM)
- ROM
- 32 KB Super Extended Color BASIC
- Video
- GIME: 16-color hi-res (HSCREEN), 40 and 80 column text
- Sound
- 6-bit DAC (IC7) and single-bit sound via the $FF20 PIA (IC4)
- OS
- Super Extended Color BASIC [3]
Chips
| Chip | Where | Role |
|---|---|---|
| MC6809E microprocessor | IC1 | Main CPU, 8-bit with 16-bit registers. Same CPU in every CoCo and in the Dragon 32 and 64. |
| GIME TCC1014 (Advanced Color Video Chip) | IC6 | CoCo 3 video, 512 K MMU, DRAM control, clocks and interrupts. Replaces the VDG and SAM. |
| MC6821 peripheral interface adapter | IC5 ($FF00, keyboard) / IC4 ($FF20, sound, cassette, RS-232) | Two 8-bit parallel ports with handshake lines. |
Ports and connectors
- Cartridge slot (CN1), 40-pin card-edge socket UNVERIFIED
- Joystick ports (JK2 right, JK1 left), 6-pin DIN socket
- RGB monitor (CN3), 10-pin header on the bottom of the board
- Composite video out (JK5), RCA phono jack
- Audio out, RCA phono jack
- Cassette (JK4), 5-pin DIN socket (180°)
- Serial I/O (JK3), 4-pin DIN socket
- RF out, RCA jack
- Transformer to main board (CN7), 3-pin connector from the transformer secondary
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | 4.75–5.25 V, ripple under 400 mV | TP1; GIME pin 35; 6809E pin 7 |
| +8 V | 7.6–8.4 V | IC36 (78L08) output |
| Raw negative | At least -10 V DC | SALT pin 15 |
Symptoms
- Dead machine or no video: check GIME, 6809E
- Bad hi-res only: check GIME
- Dead keys: check 6821 PIA
- No sound or tape: check 6821 PIA
- Bad RAM banks