INT 13h,  15h (21)       Read DASD Type                                  many

Returns the type of interface associated with a drive and also the
number of sectors the drive contains. Can be used to determine if a
diskette drive supports the sensing of a diskette change.

On entry:      AH         15h
DL         Drive number

Returns:       CF         Set if error, else cleared
AH         Disk type (see below)
Status of operation if error (see Service 01)
CX:DX      If no error and AH <> 0, then 4-byte integer
with number of sectors.


Notes:         This service is not available for PCs, PCjrs, and
XTs dated before 1/10/86.

This service allows you to determine whether a drive
supports the Change Line Status service (Service
16h). The Change Line Status informs the system
whether or not a diskette has changed since the last
access to it.

Use Service 17h (Set DASD Type) to set the type.

Disk Type
AH        Meaning
00h       Drive not present
01h       Diskette, no change line available
02h       Diskette, change line available
03h       Fixed Disk

For the AT, XT-286, and PC Convertible, the BIOS
executes INT 15h, Service 90h (Device Busy), for the
diskette (Type = 01h) and the fixed disk (Type =
00h) prior to waiting for the interrupt. INT 15h,
Service 91h (Interrupt Complete), is executed upon
completion. Also diskette operations that require
the diskette motor to be on will call INT 15h,
Service 90 (Device Busy), with the type equal to
"Diskette Drive Motor Start" (Type = FDh). This
allows the system to perform another task while the
drive motor is waiting to get up to speed.

See also: INT 13h, 01h
See also: INT 13h, 16h
See also: INT 13h, 17h

INT 13h, 15h (21) Read DASD Type many