is there a simple adaptor to use a din-4 pin wired Kensington turbo mouse Trackball
with a 2008 IMac usb input?
Love to keep old tech working.
There's a few options. You can choose cheap, or easy, but no option I'm aware of combines both.
The Griffin iMate converted the 4-pin din Apple ADB to USB. But they command a high price on the used market.
Or you can roll your own with an Arduino microcontroller:
Or a Teensy:
* note that the latter two are actually meant for ADB keyboards, so there's still some coding needed to get a mouse/trackball working.