INT 21 - Brian Antoine Seagate ST-01 SCSI.SYS - IOCTL - EXECUTE COMMANDS
        AX = 4405h
        BX = drive number (00h = default, 01h = A:, etc)
        CX = number of bytes to write
        DS:DX -> SCSIDISK control block (see AX=4403h"ST-01")
Return: CF clear if successful
            AX = number of bytes actually written
        CF set on error
            AX = error code (01h,05h,06h,0Dh) (see AH=59h)