CDU 0.6.060 - Read Me


Welcome to CDU, the ChAoS Disk Utility. This program is a low-level disk utility aimed at sector-level manipulation of disks. An obvious application for CDU is doing backups on a disk image basis. However, it can be used for a much broader range of tasks. For example, it has been used to save and restore floppy disk images, to search for and recover "lost" photograph image files on a Smart Media card and to locate "bad" sectors on hard disks.

The main benefit of using CDU are that it is a command-line utility and so lends itself to repetitive tasks better than GUI apps. Also, it operates by interpreting a simple script language and so can be made, for example, to do automatic compares after a copy operation.


In order to work, CDU merely requires that you have the MSdos executable file. Although it will run under Windows 95 and so on, when backing up, we would definitely recommend booting off of an MSdos floppy disk.

Note that CDU can, in theory at least, backup any operating system - if the BIOS can access the disk, then you should be able to manipulate it. When accessing a disk at the sector level, CDU knows nothing of partition tables, files systems and so on. This was a deliberate policy so that one could, for example, use an MSdos bootable floppy containing CDU to backup a hard disk that was dedicated entirely to, say, the Linux operating system.

Package Contents

You should have the following:

cdu.exe The CDU executable file.
*.cdu Some example CDU script files.
cduver.htm Change history of the CDU program.
cdutut.htm CDU's Tutorial.
cdu.htm This introduction to CDU.
cdufaq.htm A file of Frequently Asked Questions.
cduref.htm A CDU Reference Manual.

To actually run CDU, only the executable is required. The program can be used interactively. However, it would normally be used by specifying commands on the command-line which, of course, could cause CDU to load and run a script file.

If you are a first-time user of CDU, We suggest that you read the tutorial.


CDU is a public domain program. You are free to re-distribute CDU to third parties if:


"The authors disclaim all warranties as to this software, whether express or implied, including without limitation any implied warranties of merchantability, fitness for a particular purpose, functionality or data integrity or protection."


CDU was written by Mark ("Captain ChAoS") Davis with a small contribution from Mark Edmunds. By virtue of the fact that ChAoS had a hand in writing this program:

This program is a ChAoS Utility

We're not sure that the terms "public domain" and "copyright" aren't mutually exclusive. Even so, this software is:

Copyright © Mark Davis and Mark Edmunds, 1998-2001.

Contacting The Authors

If you have any bug reports or suggestions, you can contact the authors at the CDU email address.

If you like CDU, perhaps you'll like the rest of the ChAoS Utilities - please visit the web site.