I installed a retrofit floppy emulator in my FX-20 after some of the disks started flaking out. I don't have a support contract so I figured that I was going to have a lot of trouble sourcing replacements if the disks became unreadable. Seemed like good preventative maintenance.
I fitted an
HxC SDcard based floppy emulator. My machine loads everything from the emulated floppies: system software, language pack, parameters, E-packs, and G-code.
I did have a lot of trouble figuring out how to dump images of the original disks and what format they were in. The major confounding factor is that all of the disks spin at 360 RPM instead of the standard 300 RPM for IBM PC compatible floppies. I ended up buying a Kryoflux floppy controller to read the images -- the few PCs I could find with floppy controllers left in them couldn't make heads nor tails of the Mits floppies. The Kryoflux will work with any standard PC floppy drive and can handle reading and writing 360 RPM disks even if the drive is spinning them at 300 RPM.
The control in the FX series machine uses two different formats of disks interchangeably, "CP/M" and "DOS".
All of the system software, the language pack, and the alarm disk are in "DOS" format, which is MFM, double-sided/double-density, 1024 byte sectors, 8 sectors/track, and uses 77 tracks for a raw image size of 1310720 bytes. I think this is the same layout as the Japanese 1.2 MB standard, so if you could get your hands on a "3Mode" floppy drive and controller you might be able to dump these without a Kryoflux.
The E-packs and my pitch error disk are in "CP/M" format, which is MFM, double-sided/double-density, 256 byte sectors, 26 sectors/track, and uses 77 tracks for a raw image size of 1064960 bytes. There is no single CP/M filesystem standard, but I was able to figure out a set of parameters for the open-source "cpmtools" package to access the filesystem that the FX series control creates:
Code:
diskdef meldas
seclen 256
tracks 154
sectrk 26
blocksize 4096
maxdir 128
skew 0
boottrk 4
os 3
end
You probably won't need to touch the filesystem. I had to because my E-pack disks had intermittent read errors and I wanted to make sure that the data I pulled off of them was good.
If you have a Kryoflux you can dump your disks using its command-line `dtc` tool:
Code:
# creating an image (stream + decoded) of a DOS format disk (system disk, language disk, alarm disk):
dtc -fsystemdisk1 -i0a -n8 -z3 -s0 -e76 -v360 -tc4 -dd1 -fsystemdisk1_decoded -i4
# creating an image (stream + decoded) of a CP/M format disk (E-pack disk, pitch error/parameter disk, data disk):
dtc -fpitch-error -i0a -z1 -s0 -e76 -v360 -tc4 -dd1 -fpitch-error_decoded -i4
Decoded images can be loaded into the HxC software for conversion to their format by asking it to load a RAW image and using the previously mentioned format parameters for track/sector count and sector size.
It took me a long time to scrape all of this information together, so I figure I'll just dump it all here now. Even if it doesn't help you, Google will index it and maybe it'll save someone else some time.