Formatted Disk Image

FDI is a file image of a disc created with the Disk2FDI PC software. It is often used to read Amiga or C64 discs and other discs formatted in a way that normally can't be read with a PC.

The software uses two methods:

• Connect two floppy disk drives to a PC and fill drive-0 with an ordinary PC formatted floppy disc. Drive-1 receives a foreign format disc. Then the software reads as normal from drive-0, but then selects drive-1 instead. It thus bypasses obstacles that would make the floppy controller otherwise refuse the format of the foreign disk. In particular it gets the PLL to sync.
• Connect one disc drive to the PC via a cable that lets the parallel port interrupt pin "/strobe" trigger on the read signal. The PC only needs to make the drive spin and use correct track and head. The reading is done by software exploiting interrupt timings.

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