WDC1772 FDC Emulator: Drive Selection

04 Janurary 2005

Now it is possible to have drives supported but “turned off” for emulation.

The host emulator is no longer required to pass a valid drive selection to the FDC emulator. If the drive selection is invalid, like if the drive is turned off or disconnected - the drive signals are automatically disabled by the FDC emulator.

For example: A host Atari ST emulator can have two drives attached. Previously both were always turned on, but now it is possible to turn one off, and emulate a one-drive-only system without the host emulator worrying about conditions and I/O signals that it cannot properly control anyway.

The host emulator simply sets the maximum number of supported drives and the number of connected drives and selects the active drive from its own perspective - the rest is taken care of by the FDC emulator.