I'm pleased to announce some new information on this old scanner.
First, I have tried out portions of the 3200F driver described in this post on
the 4200F. Basic operations that worked on the 3200F, like activating the motor
and moving the scanning head to different positions, also work on the 4200F. So
it seems likely the designs are related.
Secondly, I have been in contact with an expert hardware reverse engineer, and
he volunteered to decap the CPU of the main board and post microscope images of
the die, which you can find here.
It seems clear that the CPU of both the 3200F and 4200F is an Acer Labs, Inc
("ALI") M5623. The best information I can find on it is a 2-page technical
marketing "datasheet" (which is mostly a feature overview, but has some
valuable information).
The M5623 seems to be related to the M5617, which I notice was used in the
Epson Perfection 660, which is supported by SANE (with a firmware blob?). That
may provide some additional clues. Furthermore, ALI seems to have reused the
USB-related portions of the hardware in other chips it made at the same time,
such as the 5621 USB IDE controller, for which I found a decent datasheet.
I hope this information proves useful to others. The website has been updated
accordingly (thanks to Ralph Little for merging my PR). I am in contact with
the author of the 3200F driver, Lauri Pirttiaho, and am also in the process of
reversing the firmware blob to make a memory map of the control registers and
hopefully write my own firmware (even if with limited functionality).
Best,Jeff Trull
