Apple Desktop Bus (ADB) is a daisy-chainable serial bus used by Apple computers from 1986 to 1999 for keyboards, mice, trackballs, and graphics tablets using a 4-pin Mini-DIN connector.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | ADB | Data signal bidirectional | BUS |
| 2 | PSW | Power switch | I/O |
| 3 | +5V | 5V power from Mac | PWR |
| 4 | GND | Ground | GND |