C64/128 User Port
Available at Commodore C64 & C128 computer. Can be used as RS232 port with software.
Pinout
24 PIN MALE EDGE (DZM 12 DREH) at the computer.
| Pin | Name | Description |
|---|---|---|
| 1 | GND | Ground |
| 2 | +5V | +5 VDC (100 mA max) |
| 3 | /RESET | Reset, will force a Cold Start. Also a reset output for devices. |
| 4 | CNT1 | Counter 1, from CIA #1 |
| 5 | SP1 | Serial Port 1, from CIA #1 |
| 6 | CNT2 | Counter 2, from CIA #2 |
| 7 | SP2 | Serial Port 2, from CIA #2 |
| 8 | /PC2 | Handshaking line, from CIA #2 |
| 9 | ATN | Serial Attention In |
| 10 | +9V AC | +9 VAC (+ phase) (100 mA max) |
| 11 | +9V AC | +9 VAC (- phase) (100 mA max) |
| 12 | GND | Ground |
| A | GND | Ground |
| B | /FLAG2 | Flag 2 |
| C | PB0 | Data 0 |
| D | PB1 | Data 1 |
| E | PB2 | Data 2 |
| F | PB3 | Data 3 |
| H | PB4 | Data 4 |
| J | PB5 | Data 5 |
| K | PB6 | Data 6 |
| L | PB7 | Data 7 |
| M | PA2 | PA2 |
| N | GND | Ground |
Note: 0.156" (3.96mm) contact spacing.
The Commodore 64 gives you complete control over Port B on VIA chip #1. Eight lines for input or output are available, as well as 2 lines for handshaking with an outside device. The I/O lines for Port B are controlled by two locations. One is the port itself, and is located at 56577 ($DD01 hex). Naturally you PEEK it to read an input, or POKE it to set an output. Each of the eight I/O lines can be set up as either an input or an output by setting the data direction register properly. It is located at 56579 ($DD03 hex).
Contributions
- Joakim Ögren
- Nikolas Engström
- Arwin Vosselman
- Jestin Nesselroad
- Larry Anderson
Sources
- Commodore 64 Programmer's Reference Guide
- NT Rautanen Tietokonesivut: Commodore