John Floren

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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
2 (+5V) Vcc
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.