MS DOS Command: DISKCOMP.COM

Reference from Microsoft MS-DOS cmd help

Description

Compares the contents of two floppy disks.

This command performs a track-by-track comparison. DISKCOMP determines the number of sides and sectors per track to compare based on the format of the first disk you specify.

Syntax

DISKCOMP [drive1: [drive2:]] [/1] [/8]

Parameters

drive1:	Specifies the drive containing one of the floppy disks.
drive2:	Specifies the drive containing the other floppy disk.

Switches

/1	Compares only the first sides of the disks, even if the disks are double-sided and the drives can read double-sided disks.
/8	Compares only the first 8 sectors per track, even if the disks contain 9 or 15 sectors per track.

Related Command

For information about comparing two files, see the FC command.

Remarks

Invalid drive for DISKCOMP

The DISKCOMP command works only with floppy disks. You cannot use DISKCOMP with a hard disk. If you specify a hard disk drive for drive1 or drive2, DISKCOMP displays the following error message:

Invalid drive specification

Specified drive does not exist

or is non-removable

DISKCOMP messages

If all tracks on the two disks being compared are the same, DISKCOMP displays the following message:

Compare OK

If the tracks are not the same, DISKCOMP displays a message similar to the following:

Compare error on

side 1, track 2

When DISKCOMP completes the comparison, it displays the following message:

Compare another diskette (Y/N)?

If you press Y, DISKCOMP prompts you to insert disks for the next comparison. If you press N, DISKCOMP stops the comparison.

DISKCOMP ignores a disk's volume number when it makes the comparison.

Omitting drive parameters

If you omit the drive2 parameter, DISKCOMP uses the current drive for drive2. If you omit both drive parameters, DISKCOMP uses the current drive for both. If the current drive is the same as drive1, DISKCOMP prompts you to swap disks as necessary.

Using one drive for the comparison

If you specify the same floppy disk drive for drive1 and drive2, DISKCOMP does a comparison by using one drive and prompts you to insert the disks as necessary. You might have to swap the disks more than once, depending on the capacity of the disks and the amount of available memory.

Comparing different types of disks

DISKCOMP cannot compare a single-sided disk with a double-sided disk or a high-density disk with a double-density disk. If the disk in drive1 is not of the same type as the disk in drive2, DISKCOMP displays the following message:

Drive types or diskette types not compatible

Using DISKCOMP with networks and redirected drives

DISKCOMP does not work on a network drive or on a drive created or affected by a SUBST command. If you attempt to use DISKCOMP with a network drive or a drive created by the SUBST command, DISKCOMP displays an error message.

Comparing an original disk with a copy

When you use DISKCOMP with a disk that you made with the COPY command, DISKCOMP may display a message similar to the following:

Compare error on

side 0, track 0

This type of error can occur even if the files on the disks are identical. Although the COPY command duplicates information, it doesn't necessarily place it in the same location on the destination disk. For more information about comparing individual files on two disks, see the FC command.

DISKCOMP exit codes

The following list shows each exit code and gives a brief description of its meaning:

0	The disks are the same.
1	Differences were found.
2	The user pressed CTRL+C to stop the process.
3	A critical error occurred.
4	An initialization error occurred.

You can use the ERRORLEVEL parameter on the IF command line in a batch program to process exit codes returned by DISKCOMP. For an example of a batch program that processes exit codes, see the CHOICE command.