Archive for June 3rd, 2013

Floppy Drive Support in System Rescue CD

For obscure reasons, I’m kibitzing on a project to rehabilitate an ancient Brother industrial sewing machine. It has a floppy disk drive that stored various custom stitch patterns, but it now crashes / jams / stalls after loading any of the patterns.

I booted an old PC that had a floppy drive using System Rescue CD, only to discover that /dev/fd0 didn’t exist. A bit of search-fu revealed that the floppy kernel module isn’t automagically loaded: a simple modprobe floppy did the trick, after which mount -o ro /mnt/floppy worked fine (it’s in fstab, even if the kernel module isn’t loaded).

The floppy was in IBM PC-DOS format, as you might expect in a system with ICs date-coded in the early 90s and an 8085 CPU (not an 8088 or 8086). Applying dd bs=512 if=/dev/fd0 of=/tmp/floppy.bin produced a measly 12 kB file containing the boot sector, many binary zeos, a line or two of pinball panic, and more binary zeros up to the 0x3000 file size, where it ended due to a hard read error.

So now we know there’s no point in trying to run from the floppy, because there’s nothing to run. According to the instructions, the sewing machine can write to the floppy, so we can examine some of those results to see what the data structures should be.

A new-to-me off-lease Dell Optiplex 760 that I just picked up (for the M2’s LinuxCNC controller) has a floppy drive, so I can let that old hulk go to the recycler. I don’t see a big duty cycle for the floppy, but ya gotta have stuff…