Apricot mice are rare, I don't own one
A few months back, I was able to reverse engineer the protocol used by the Apricot wireless IR mouse and was able to make a USB mouse to Apricot IR adaptor which I used with my Apricot F1 and Portable
https://woof.tech/@crashtestdev/115715072242669893
So I thought I'd have a crack at the wired mouse, visually, the wired and IR mouse are identical, so it stands to reason they used the same OEM
Referring to the technical manual, I learned that the keyboard and mouse sent data over RS-232 serial 8n1 @ 7800 baud (on page 218), and then on page 223, we learn that the mouse shared the bus with the keyboard, same as the wireless, but since it is wired, the mouse also asserts a REQ line to the keyboard controller (a whole damn 6301
) and awaits an ACK to be asserted before sending any data, scrolling further down to page 226, hex codes 0x70-0x7f are the mouse codes, meaning that it sends 4 bits per byte which is ALSO the same as the wireless mouse, and 0xEF is the mouse packet header, which the mouse also has
It stands logically to reason then that the wires mouse protocol is going to be similar to the wireless one
Wanting to verify further, I took a look at the QDAE emulator source, and BAM! Right there, bin/xi_keyboard.cxx on line 87, 6 byte packet, begins with 0xEF, first data byte is the button statuses, followed by y and x coordinates, in big endian format