[PC] [XT] [AT]
Expects: AH    04H
AL    sector count (see notes)
CH    track (cylinder) number (0-n)    
CL    sector number (1-n)                 (see notes)
DL    drive: 0-3=diskette; 80H-81H=hard disk
DH    head number
                                                                  
Returns: AH    BIOS disk error code if CF is set to CY
                                                                  
Info: This verifies that the CRC  was correct for the specified
sector(s).  It does NOT actually compare disk data to memory.

Notes:   CX is used as a 6-bit and 10-bit field to specify sector and
cylinder.  See INT 13H 02H for details.

  On diskette writes, this function stops a multi-sector
operation at the last sector in a track.

  On hard disks (with XT and AT BIOSes), a multi-sector operation
continues on the next higher head of the same cylinder and if
necessary, advances to the next higher cylinder on the first
head.

  Parameters are the same as for INT 13H 02H (read sectors).

See Also: DOS fn 440dH 62H (IOCTL verify track)
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INT 13H 04H: Verify Sectors