HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                            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

Esc or Alt-X to exit media descriptor byte Home/PgUp/PgDn/End ←↑↓→
Converted to HTML in 2006 by Timo Bingmann