The CPC doesn't support floppy DMA transfers, and the FDC's Interrupt signal isn't used in the CPC.
In The FDC controller in the CPC, or [[Amstrad External Disk Drive|Amstrad DDI-1]] expansion doesn't have the US1 pin of the FDC is not connected, making . This means it impossible to can only select floppy drives 0 and 1, and not drives 2 and 3. The However, the FDC in the Vortex interface does have the US1 pin connected, so it can manage up to 4 floppy drives 0 and 1 are selected instead.
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