Microsoft KB Archive/57431

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Knowledge Base

DISKCOPY May Require Multiple Disk Swaps

Article ID: 57431

Article Last Modified on 11/16/2006


  • Microsoft MS-DOS 3.1
  • Microsoft MS-DOS 3.2 Standard Edition
  • Microsoft MS-DOS 3.21 Standard Edition
  • Microsoft MS-DOS 3.3 Standard Edition
  • Microsoft MS-DOS 3.3a
  • Microsoft MS-DOS 4.0 Standard Edition
  • Microsoft MS-DOS 4.01 Standard Edition
  • Microsoft MS-DOS 5.0 Standard Edition

This article was previously published under Q57431


The behavior of the DISKCOPY command varies depending on whether you are using a single floppy disk or copying between two disks. When you use DISKCOPY on a single floppy disk drive, it does not ask you whether you want to copy another disk; instead, it asks for the next source disk. When you use DISKCOPY between two floppy disk drives, the copy occurs without any request.


This is expected behavior. For larger disks, DISKCOPY can only read a portion of the disk into memory at one time; therefore, you must switch between the source and destination during the copy.

The DISKCOPY utility provided with Microsoft MS-DOS Packaged Product makes an exact copy of one floppy disk onto another floppy disk. To do this, DISKCOPY loads the contents of the disk into memory sector by sector and then writes these sectors back out to the destination disk.

Because many different types of floppy disk media have a capacity larger than that of the computer's available memory, DISKCOPY must make the copy in several steps. For 1.44 MB floppy disks, it takes a minimum of three steps. The copying process is broken into even more steps if available memory is reduced.

This memory reduction is most noticeable if you are using a single disk drive for the copy. Each time memory is filled from the source disk, DISKCOPY must request that the destination disk be inserted so that the current contents of memory can be written. After the memory has been written to, DISKCOPY then requests the source disk again to read the next section of the disk into memory.

Additional query words: 3.20 3.21 3.30 3.30a 4.00 4.01 5.00 noupd

Keywords: KB57431