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

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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. 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: 1

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