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

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Article ID: 74496 - View products that this article applies to.
This article was previously published under Q74496
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SUMMARY

Microsoft MS-DOS reserves certain names for system device drivers. If you try to name a file using one of these names, you will receive the following 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 two commands:

  • mem /d | more
  • debug d 0070:0000

Properties

Article ID: 74496 - Last Review: May 12, 2003 - Revision: 2.0
APPLIES TO
  • 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
Keywords: 
KB74496
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.

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