Oct 3, 2026, 9:55 AMApparently my hobby is reverse engineering Apple “custom” ICs from the 80s.
Here’s another one that I’ve finally gotten around to testing - the 6805 microcontroller in the Apple ii mouse card can be replaced with a 68705P3!
- Oct 3, 2026, 9:55 AM
Replies
- Oct 3, 2026, 9:59 AM
It’s still relatively funny to me that I boot my Apple IIe from a SCSI CD drive. It’s like sure it works but it’s the most round about way of doing it.
Anyway here is the proof! The chip with the “mouse” label is the one I replaced
- Oct 3, 2026, 10:01 AM
I must admit I didn’t exactly do anything ground breaking. The firmware had been dumped here:
https://github.com/freitz85/AppleIIMouse
The file is “6805.bin”, and using an appropriate programmer (in my case an LV48), a replacement 68705 was programmed. I didn’t even need to change any of the firmware- it just worked!
- Oct 3, 2026, 10:03 AM
It’s also worth noting that the Pico boards for the Apple ii can also emulate a mouse card.
However, there’s something nice about building a 1:1 replica of a card - which I’ve already designed.
The github repository also has the PAL equations and the firmware - I just need to build my own card!
- Oct 3, 2026, 10:10 AM
Aha, I do have a photo of the mouse card replica!
