fdc —
Amiga custom chip floppy disk controller device
fdc0 at mainbus0
fd* at fdc? unit ?
The fdc device driver provides support for the mainboard
  floppy disk controller and floppy disk drives on Amiga systems.
The driver supports the following floppy diskette formats by using
    particular partitions:
  - 880KB 3.5-inch 11 sectors/track (``Amiga'') (a)
-  
- 1.76MB 3.5-inch 22 sectors/track (``Amiga'') (a)
-  
- 880KB 5.25-inch 11 sectors/track (``Amiga'') (a)
-  
- 720KB 3.5-inch 9 sectors/track (``MS-DOS'') (b)
-  
- 1.44MB 3.5-inch 18 sectors/track (``MS-DOS'') (b)
-  
- 720KB 5.25-inch 9 sectors/track (``MS-DOS'') (b)
-  
 
On systems equipped with floppy disk drives capable of using high-density floppy
  diskettes, the driver automatically detects whether the inserted floppy
  diskette is either a double-density or a high-density medium.
  - fdc: unable to allocate DMA buffer
- The driver found the controller, but was unable to allocate the amount of
      chip memory required for its DMA buffers.
In order to detect a floppy disk drive's capability of using high-density media,
  a high-density diskette has to be inserted for the duration of the
  autoconfiguration phase of the drive.The fdc driver supports neither the
    fdformat(1) facility nor
    the <sys/fdio.h>
  interface.