Click above to get retro games delivered to your door ever month!

  In the PC/AT and PS/2 BIOS, service 08H (decimal 8) returns disk-drive
  parameters for the drive whose number you specify in DL. DL reports the
  number of disk drives attached to the disk controller, so diskette and
  fixed-disk drive counts are reported separately. DH reports the maximum
  head number, CH returns the maximum cylinder number, and CL returns the
  highest valid sector number plus the 2 high-order bits of the maximum
  cylinder number.

  For diskette drives, the PC/AT ROM BIOS (after 1/10/84) and the PS/2 ROM
  BIOS also report the drive type in BL: 01H = 360 KB, 5-1/4 inch; 02H = 1.2
  MB, 5-1/4 inch; 03H = 720 KB, 3-1/2 inch; 04H = 1.44 MB, 3-1/2 inch.