PET / CBM
All-in-one with IEEE-488.
Open the PET / CBM in Retro Bench- Also
- 2001, 3000, 4000, 8000
- Year
- 1977
- CPU
- 6502 @ 1 MHz
- RAM
- 4-32 KB
- ROM
- BASIC, EDITOR, KERNAL, char (24-pin mask ROMs)
- Video
- Discrete / 6545 CRTC
- Sound
- One beep (VIA CB2)
- OS
- BASIC 1.0-4.0
Chips
| Chip | Where | Role |
|---|---|---|
| 6502 / 65C02 CPU | CPU | |
| 6545 CRTC | Video timing and screen addressing (later PET boards) | |
| 6520 PIA | Keyboard, cassette 1, IEEE-488 data (PET) | |
| 6522 VIA | Two 8-bit ports, timers, serial and user port | |
| 2114 SRAM 1K x 4 | Static RAM (ZX80 and ZX81 1K) | |
| 2364 Mask ROM 8K×8 | BASIC and KERNAL ROMs (C64); BASIC and KERNAL (VIC-20, PET); character ROM (C128) | |
| 2332 Mask ROM 4K×8 | Character ROM (C64, VIC-20, PET) |
Ports and connectors
- IEEE-488 bus (J1), 24-contact card edge (2 × 12, Commodore)
- User port (J2), 24-contact card edge (2 × 12)
- Cassette 1 (J3), 12-contact card edge (2 × 6)
- Cassette 2 (J6), 12-contact card edge (2 × 6)
- Video to the built-in monitor (J7), 7-pin header
- Memory expansion (J4, J9), Board connectors UNVERIFIED
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | +5 V | 6502 pin 8; VR3 and VR4 (LM340-5) outputs |
| +12 V | +12 V | VR5 (7812) output; TP6 |
| -5 V | -5 V | VR6 (7905) output; TP10 |
| +9 V unregulated | About +9 V DC | J8 pin 2; J11 pins 1, 4, 6 (raw power header) |
Symptoms
- Black screen, no startup chirp: check 6502, 2364
- Garbage screen: check 2114
- No display (later boards): check CRTC
- Dead keyboard: check PIA
- No disk or IEEE-488: check PIA, VIA
- No beep: check VIA