Guest
#4786384
'morning, I've found numerous articles discussing how to emulate a floppy disk DRIVE, here and elsewehere and there even seem to exist commerial solutions. 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? Josef