Firmware version 1.7 for the Altair FDC+ adds a new drive type which adds 8” SSSD soft-sector support to the Altair FDC+. The drive type added is the iCOM/Pertec/Altair FD3712 drive cabinet. This drive cabinet/controller and its S-100 interface board implement the 8in SSSD IBM-3740 soft-sector format that was very common in the 1970's. The FD3712 did this with discrete TTL logic back in the days before LSI floppy controller ICs like the WD1771 were available.
A video about the FD3712 drive cabinet can be seen here: https://youtu.be/Md1oEWf171o
Version 1.7 firmware for the FDC+ and the latest manual can be found here: https://deramp.com/downloads/altair/hardware/fdc+/
CP/M 2.2 for the Altair and FD3712 on the FDC+ can be found here: https://deramp.com/downloads/altair/sof ... /FDC+3712/
Mike