Mysteries of the Griffin iMate

3 days ago

The author restores a vintage Apple Extended Keyboard II from 1990, cleaning it and trying to connect it via USB.
Instead of building a custom adapter, they buy a Griffin iMate ADB-to-USB converter, but it fails due to a USB reset loop.
Research reveals the iMate has a hidden CR1225 battery for powering on old Macs via the keyboard's power button.
Replacing the flat battery fixes the issue, but the author investigates further to understand the circuit.
Analysis shows noise on the PSW signal causes USB errors when the battery is dead, solved by adding a decoupling capacitor.
The author speculates on design choices, like why a battery was needed and why Griffin never mentioned it.
Despite fixing the iMate, the author considers other adapters for better key mapping support.

Hasty Briefsbeta