Posted 2022/7/8
Classic Macintosh Mouse Adapter
As I speculated before, the USB adapter I built last year works just fine with the 9-pin DB9 mouse from the original Mac and Mac Plus:
The Arduino source is available here. Here’s how I wired up the Mac mouse:
| Mouse port pin | Arduino pin |
|---|---|
| 1 (GND) | GND |
| 2 (+5V) | Vcc |
| 3 (GND) | GND |
| 4 (X2) | 3 |
| 5 (X1) | 2 |
| 6 (NC) | (not connected) |
| 7 (button) | 9 |
| 8 (Y2) | 1 |
| 9 (Y1) | 0 |
Note that I added pull-up resistors on the mouse pins as I should have done from the start.