Commodore Plus/4
The C16's big brother: 64 KB, user port, RS-232 and built-in office suite.
Open the Commodore Plus/4 in Retro Bench- Also
- 264 series
- Year
- 1984
- CPU
- 7501/8501 @ 0.89/1.79 MHz (NTSC)
- RAM
- 64 KB (60 KB free)
- ROM
- BASIC 3.5 + KERNAL + 3-Plus-1
- Video
- TED 7360
- Sound
- TED, 2 voices
- OS
- Commodore BASIC 3.5
Chips
| Chip | Where | Role |
|---|---|---|
| 7360 / 8360 TED | U1 | Video, sound, DRAM controller, MMU, keyboard scan |
| 7501 / 8501 CPU | U2 | CPU |
| PLA 82S100 | U19 | Address decode + bank switching |
| 6529 Single Port Interface | U5, U27 (keyboard latch and user-port/cassette-sense port) | Keyboard column latch / user port |
| 6551 ACIA | U3 | RS-232 serial (Plus/4 only) |
| 4164 DRAM 64K×1 | U11-U18 | Main RAM (8 chips = 64 KB) |
| 23128 Mask ROM 16K×8 | U23 (BASIC), U24 (KERNAL), U25, U26 (3-plus-1) | BASIC and KERNAL ROMs (C16, Plus/4, C64C short board, C128) |
Ports and connectors
- Power in (+5 V DC, 9 V AC), Square 4-pin power socket UNVERIFIED
- User port (RS-232 / parallel), 24-contact card edge (2 × 12)
- Joystick 1 / 2, Mini-DIN 8 (264 series)
- Cassette (1531 Datasette), Mini-DIN 7
- Serial (IEC) disk / printer, DIN-6
- Video / audio, DIN-8 (262°)
- Memory expansion port, 50-contact card edge (2 × 25)
Power rails
| Rail | Expect | Measure at |
|---|---|---|
| +5 V | +5 V (the PSU drawing sets 5.2 V) | plus4-power pin 1 (power socket); TED pin 4; 7501 pin 5; 4164 pin 8 |
| 9 V AC | About 9 V AC between the two 9 V AC pins | plus4-power pins 3, 4 (power socket); plus4-user pins 10, 11 (user port) |