I don't know if it is any help, but Outbound (the Macintosh Laptop clone company from the 80s/90s, managed to implement the SWIM functionality using a WD37C65, a WD92C32, a 28C64 EEPROM, and a Xicor 9103 digital potentiometer. I think there were a couple of discrete logic chips, like 244s and maybe a few transistors on there too. One of these days, I must trace out a schematic.
Anyway, all that stuff interfaced with a standard old Citizen brand 1.44MB floppy drive (such as a W1D) and provided a Macintosh compatible drive which could read and write 400K and 800K disks as well as the easier 1.44K disks.
The laptop that used this controller board had Plus ROMs inside.
Gah! I almost forgot. There's a GAL on the board. Little 20 pin 16V8 jobber. I would have cloned the floppy controller by now, except I don't know what's in that GAL.
Anyway, all that stuff interfaced with a standard old Citizen brand 1.44MB floppy drive (such as a W1D) and provided a Macintosh compatible drive which could read and write 400K and 800K disks as well as the easier 1.44K disks.
The laptop that used this controller board had Plus ROMs inside.
Gah! I almost forgot. There's a GAL on the board. Little 20 pin 16V8 jobber. I would have cloned the floppy controller by now, except I don't know what's in that GAL.