Diskcopy

Index

DISKCOPY is used to duplicate floppy disks. Any data on the destination disk is overwritten.

Syntax:

DISKCOPY drive1: [drive2:] [/1] [/V] [/M]

drive1Drive containing disk to be copied from (and to, if the computer has only one floppy drive) .
drive2Drive containing disk to be copied to (if different from drive1.
/1Copies only the first side of the disk.
/VVerifies that the information is copied correctly.
/MForce multi-pass copy using memory only.

Notes:

  1. DISKCOPY is designed to duplicate standard floppy disks by making a byte-by-byte copy of the source disk to the destination disk.
    It follows that:
    • It will not work with hard drives, CDs, network drives, or Zip, Jazz, etc. type drives;
    • Source and destination disks must be of the same type, size, and capacity. If they are not, an error message is displayed:

      
      C:\WINDOWS>diskcopy a: a:
      Insert SOURCE diskette in drive A:
      Press any key to continue . . .
      
      Copying 80 tracks, 18 sectors per track, 2 side(s)
      Reading from source diskette . . .
      
      Insert TARGET diskette in drive A:
      Press any key to continue . . .
      Writing to target diskette . . .
      
      Drive types or diskette types not compatible
      Copy process ended
      Copy another diskette (Y/N)?
      
      

      (BUT see "Tricks" below...)

    • If the source disk is a system disk (i.e. bootable), the destination disk will be too. Conversely, if the source is not a system disk, the destination disk won't be either. This is so however the destination disk was originally formatted.

  2. Once the DISKCOPY command has been entered, prompts to insert source and destination disks are displayed as the process requires. When a single drive is used for both the source and destination disks, an image of the source disk is stored in the directory specified by the TEMP environmental variable. How much disk swapping is required depends on the capacity of the disks and the free space in TEMP.

  3. If the destination disk is not formatted, it is automatically formatted appropriately before the copying process begins.

Exit Codes:

0The copy operation was successful
1A non-fatal read/write error occurred
2Copying was terminated by Ctrl-C before it was complete.
3A critical error occurred.
4An initialization error occurred. Most often caused by the two floppy disks being of different types (1.44M and 720K perhaps?)

Tricks

As mentioned in "Note #1" above, DISKCOPY is designed to make identical copies of floppies and it is generally understood that it cannot be used to copy the contents of a 1.2Mb 5.25" floppy onto a 1.4Mb 3.5" floppy (or even a 720Kb 3.5" floppy to a 1.4Mb floppy). In most cases the simple workaround is to use COPY or XCOPY to copy the files from the one disk to the other. However, there are occasions when the "simple" workaround is not appropriate for one reason or another and alternative measures are called for.

In a newsgroup discussion (Ref.1) Kevin G. Rhoads described a way to make DISKCOPY work between disks of different formats by modifying the boot sector of the destination disk to match that of the source.

Yes, you CAN diskcopy a 1.2M onto a 1.44M floppy -- BUT you need to be tricky.

The easiest way to do it, is to use DEBUG or a disk editor and copy the boot sector of the 1.2M onto the boot sector of the 1.44M.

Then remove the 1.44M and access the 3.5" drive, abort at the error message. This forces DOS to recognize the floppy ain't there no more. When you re-insert the 1.44M with the 1.2M boot sector, DOS will read the boot sector and "recognize" the disk as a 1.2M formatted disk. NOW you can diskcopy from the 1.2M 5.25" floppy onto the "1.2M" 3.5" floppy.

This trick is useful when migrating old software's install disks to a machine with only a 3.5" drive. I have used it with several versions of DOS on several machines -- I only saw it fail once, on a machine with a strange BIOS that had lots of other compatibility problems.

The "hybrid" disk will still be formatted to 18 sectors/track, but DOS will recognize the existence of only the first 15 sectors on each track. Similar tricks can be used to place a 720k disk image on a 1.2M disk; or a 360k disk image on any of the other standard disk types.

The hybrid disk will work with DOS 3.2 and later, Win95 (original), probably with Win95 OSR2 and Win98, and probably NOT with NT.

The "trick" to all these sub-formatted hybrid disks, is to recognize that DOS loads the info. on the disk layout from the boot sector when it first recognizes there is a new disk in the drive. To change what DOS thinks the disk layout is, you change what is in the boot sector THEN force DOS to re-register the disk.

Several things can get DOS to re-register the disk, but the only way that works reliably under all DOS versions in all cases seems to be taking the disk out of the drive and trying to access it, then aborting the access. Then when the disk is re-inserted, DOS will treat it as a new floppy and register the disk parameters from the boot sector.

Kevin G. Rhoads, Ph.D. (The Cheshire Cat for official Internet mascot.)

File Details

File NameDefault LocationDos Ver.Win Ver.SizeDateSource
Diskcopy.comc:\windows\command 7.0Win95 21 95911/07/95win95_08.cab
7.1Win95 (OSR2.x) 21 975124/08/96win95_13.cab
Win98 21 975111/05/98win98_28.cab
Win98 SE 21 975123/04/99win98_25.cab

Superscripts denote which same size files, if any, are identical (using FC).

References

Ref.#FromTitleNewsgroupDate
1Kevin G. RhoadsRe: diskcopycomp.os.msdos.misc08 Jan 2000

If you should have any comments or suggestions,
please contact: Bob Watson
.
This page last revised:
August 27, 2000.