A Moogle  🏳️‍🌈 💻 🎮 🎶 🇸🇪

It's a special brand of whacked out, yet it makes a perverse kind of sense. From the software's POV there's no difference between a hard disk and a floppy disk, except the floppy disk has only two heads and fewer cylinders.

Ultimately it uses an 8" double-sided double-density drive with 78 tracks, and it treats a given track on both side 1 and side 2 as a continuous double-length track. MFM. No sectoring to my knowledge, a track just leads off with 300 microseconds of zeroes after the index pulse.

Oooh, that is weird. Didn't they use a Transputer to run the floppy drive?

Maybe in the later machines, but this is the OG model from 1981. The controller, to the extent that there is one, is a 6803 with 2k of PROM, a FDC9216B PLL to do clock/data separation, and a bucket of discrete logic to make it masquerade as an SMD hard disk.

I didn't do anything with the floppy, but I did design the backwards compatibility disk controller for the V series, my only HW project, to handle CDC 80 Mb cartridges. So I might be able to give a little help.

Are those CDC cartridges what I knew as 'RSDs' at the BBC. (Ironically I went from having a Henry and a D1 next to me at Pear Tree Lane to a Classic Paintbox, Slidefile and Aston Caption at BBC East in Norwich 18 months later).