Commodore VIC-20 User I/O
24 pin male edge (DZM 12 DREH) at the computer.
Note: pin 2 is +5VDC, pins 10 and 11 are +9VAC
| Upper side | ||
| 1 | GND | Ground |
| 2 | +5VDC | 100mA max |
| 3 | /RESET | By grounding this pin, the VIC will do a cold start, resetting completely and erasing any program in memory. |
| 4 | JOY0 | This pin is connected to joystick switch 0 (See game port). |
| 5 | JOY1 | (See game port.) |
| 6 | JOY2 | (See game port.) |
| 7 | LIGHT PEN |
This pin also acts ad the input for the joystick fire button (See game port). |
| 8 | CASSETTE SWITCH |
This pin is connected to the sense cassette switch line. |
| 9 | SERIAL ATN IN |
This pin is connected to the ATN IN line of the serial bus. |
| 10 | 9VAC | (+ phase) Connected directly to the VIC transformer. |
| 11 | 9VAC | (- phase) Connected directly to the VIC transformer. |
| 12 | GND | Ground |
| Bottom side | ||
| A | GND | Ground |
| B | CB1 | The VIC 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 37136 ($9110 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 37138 ($9112 hex). |
| C | PB0 | |
| D | PB1 | |
| E | PB2 | |
| F | PB3 | |
| H | PB4 | |
| J | PB5 | |
| K | PB6 | |
| L | PB7 | |
| M | CB2 | |
| N | GND | Ground |
Source: VIC-20 User Manual, VIC-20 Programmer's Reference Guide
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