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MS-DOS Device Driver Names Cannot be Used as File Names

This article was previously published under Q74496
Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.
SUMMARY
Microsoft MS-DOS reserves certain names for system device drivers. Ifyou try to name a file using one of these names, you will receive thefollowing error message:
Write Fault Error Writing Device <FILENAME.EXT>
Abort, Retry, Ignore, Fail?
The solution is to change the file name.
MORE INFORMATION
Below is a list of default device driver names.
   Name    Function   ----    --------   CON     Keyboard and display   PRN     System list device, usually a parallel port   AUX     Auxiliary device, usually a serial port   CLOCK$  System real-time clock   NUL     Bit-bucket device   A:-Z:   Drive letters   COM1    First serial communications port   LPT1    First parallel printer port   LPT2    Second parallel printer port   LPT3    Third parallel printer port   COM2    Second serial communications port   COM3    Third serial communications port   COM4    Fourth serial communications port				
To identify system device driver names, use one of the following twocommands:

  • mem /d | more
  • debug d 0070:0000
6.22 2.x 3.x 4.x 5.00 5.00a 6.00 6.20
Properties

Article ID: 74496 - Last Review: 05/12/2003 20:59:36 - Revision: 2.0

  • Microsoft MS-DOS 2.11 Standard Edition
  • 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
  • Microsoft MS-DOS 5.0a
  • Microsoft MS-DOS 6.0 Standard Edition
  • Microsoft MS-DOS 6.2 Standard Edition
  • Microsoft MS-DOS 6.21 Standard Edition
  • Microsoft MS-DOS 6.22 Standard Edition
  • KB74496
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