6 PIN MINI-DIN FEMALE (PS/2 STYLE) (A4000/CD32/CDTV) at the computer
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | /DATA | IN/OUT | Data |
| 2 | n/c | - | Not connected |
| 3 | GND | - | Ground |
| 4 | +5V | OUT | +5 Volts DC (100 mA max) |
| 5 | CLOCK | IN | Clock |
| 6 | n/c | - | Not connected |
The Amiga A4000 and CDTV connect an external keyboard through a 6-pin mini-DIN female socket at the computer, sharing the same physical shell as the PS/2 keyboard connector. The interface carries the synchronous serial keyboard protocol defined in the Amiga Hardware Reference Manual: two open-collector signal lines, KDAT and KCLK, with pull-up resistors present in both the keyboard unit and the host computer. Pins 2 and 6 are unconnected on the A4000/CDTV variant, distinguishing it from the Amiga CD32, which repurposes those positions for a combined serial port. The pin table above applies to the A4000 and CDTV only.
Notes
- Direction is computer relative to keyboard.
- Both KDAT (/DATA, pin 1) and KCLK (CLOCK, pin 5) are open-collector lines; pull-up resistors are fitted in both the keyboard microprocessor and the host computer.
- Signal levels are active-low: +5 V on the line corresponds to logic 0, and 0 V to logic 1.
- KCLK is unidirectional (driven by the keyboard); KDAT is bidirectional (driven by both keyboard and computer). The computer acknowledges each received byte by pulling KDAT low for at least 85 microseconds.
- Data is transmitted at approximately 17 kbits/sec (60 µs per bit) in 8-bit serial words with a rotated bit order (transmitted sequence: bits 6-5-4-3-2-1-0-7).
- Key-down and key-up events are both signalled; the upstroke key code equals the downstroke code plus 0x80.
- Inside the A4000, KDAT connects to the SP pin of the 8520 CIA-A, and KCLK connects to the CIA-A CNT pin.
- The Amiga CD32 uses a physically identical 6-pin mini-DIN socket but assigns pin 2 to serial transmit and pin 6 to serial receive; the CD32 pinout is documented on a separate page.
Signals
- /DATA — Bidirectional keyboard serial data line (active-low open-collector); connects to CIA-A SP pin inside the computer.
- n/c (pin 2) — Not connected on A4000/CDTV.
- GND — Signal and power ground.
- +5V — Power supply to the keyboard unit.
- CLOCK — Unidirectional keyboard clock output (active-low open-collector); connects to CIA-A CNT pin inside the computer.
- n/c (pin 6) — Not connected on A4000/CDTV.