INT 13 - DISK - WRITE DISK SECTOR(S)
        AH = 03h
        AL = number of sectors to write (must be nonzero)
        CH = low eight bits of cylinder number
        CL = sector number (bits 0-5)
             high two bits of cylinder (bits 6-7, hard disk only)
        DH = head number
        DL = drive number (bit 7 set for hard disk)
        ES:BX -> data buffer
Return: CF set on error
        CF clear if successful
        AH = status (see AH=01h)
        AL = number of sectors transferred
Notes:  errors on a floppy may be due to the motor failing to spin up quickly
          enough; the write should be retried at least three times, resetting
          the disk with AH=00h between attempts
        AWARD AT BIOS extended to handle more than 1024 cylinders by placing
          bits 10 and 11 of the cylinder number into bits 6 and 7 of DH
SeeAlso: AH=0Bh