INT 13h,  17h (23)       Set DASD Type for Format                        many

    This service sets the type of diskette for a particular type of drive
    in order that the disk is properly formatted. This service can be
    performed on diskettes only.

       On entry:      AH         17h
                      AL         Diskette/drive combination (see below)
                      DL         Drive number (bit 7 must be clear)

       Returns:       CF         Set if error, else cleared
                      AH         Status of operation (see Service 01h)

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                    Diskette/Drive Combination
                      AL         Meaning
                      01h        Diskette 320/360K in 360K drive
                      02h        Diskette 360K in 1.2M drive
                      03h        Diskette 1.2M in 1.2M drive
                      04h        Diskette 720K in 720K drive
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       Notes:         This service is not available for PCs, PCjrs, and
                      XTs dated before 1/10/86.

                      A diskette/drive combination value of 04h is not
                      valid for ATs before 6/10/85.

                      For the AT, XT-286, and PC Convertible, the BIOS
                      executes INT 15h, Service 90h (Device Busy), for the
                      diskette (Type = 01h) prior to waiting for the
                      interrupt. INT 15h, Service 91h (Interrupt
                      Complete), is executed upon completion. 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.