Media Descriptor Byte

	Media Descriptor Byte Layout:

	│7│6│5│4│3│2│1│0│ IBM Media Descriptor Byte
	 │ │ │ │ │ │ │ └─── 1 = 2 sided, 0 = not 2 sided
	 │ │ │ │ │ │ └──── 1 = 8 sector, 0 = not 8 sector
	 │ │ │ │ │ └───── 1 = removable, 0 = not removable
	 └─┴─┴─┴─┴────── must be set to 1

	F8	Hard disk
		Double sided  18 sector diskette  PS/2 1.44 Mb. DSQD

	F9	5¼  Double sided, High Density diskette (15 sector)
		3½  Double Sided, Double High Density diskette (9 sector)

	FA	Ram disk (not all Ramdisks use this)

	FC	5¼ Single Sided, Double Density diskette (9 sector)
		8  inch Double Sided, Single Density diskette

	FD	5¼ Double Sided, Double Density (9 sector)
		8  inch Double Sided Single Density (26 sector) (IBM 3740
		   format) 128 bytes per sector, soft sector, 4 sectors
		   cluster, 4 reserved sectors, 2 FATs, 68 directory entries,
		   77*26*2 sectors.

	FE	5¼ Single Sided, Double Density diskette (8 sector)
		8  inch Single Sided, Single Density diskette (26 sector)
		   (IBM 3740 format) 128 bytes per sector, soft sector,
		   4 sectors per cluster, 1 reserved sector, 2 FATs. 68
		   directory entries, 77*26 sectors.
		8  inch Double Sided, Double Density (8 sector), 1024 bytes
		   per sector, soft sector, 1 sector per cluster, 1 reserved
		   sector, 2 FATs, 192 directory entries, 77*8*2 sectors. To
		   distinguish from 8 inch SS/SD attempt read of side 2.

	FF	5¼ Double Sided, Double Density diskette (8 sector)

	- see also   INT 21,1B  INT 21,1C  FAT