I've found numerous articles discussing how to emulate a floppy disk
DRIVE, here and elsewehere and there even seem to exist commerial
Yesterday I revived an old SB180FX (HD64180 CPU with a CP/M compatible
OS) and had been contemplating beforehand what to do if the floppy
drives or the disks failed. I was wondering if it were possible to
replace the floppy controller (FDC9266) by a microcontroller that
emulated the FDC (register read/write, DMA) and stored the data blocks
on an SD card or such (anyone know if SD cards with 1.44MB capacity
exist? ;-) ).
I would read/write the raw data on my PC, so the controller would just
map the floppy's blocks 1:1 to the SD card or even map all four drives
to separate sections on the SD card.
The bus speed to the processor (running a ~12MHz) would need some
attention, maybe adding hardware support in the form of a flipflop which
generates WAIT cycles (within reasonable limits) by being set
automatically by any access and which is then reset by the
microcontroller. This only affects the reading/writing of commands and
status, after that the microcontroller would work internally
transferring data via (emulated) DMA.
I'd prefer an ATmega of sorts.
Question: has anyone done this before?