DOCUMENT:Q74496  17-DEC-2000  [msdos]
TITLE   :MS-DOS Device Driver Names Cannot be Used as File Names
PRODUCT :Microsoft Disk Operating System
PROD/VER:MS-DOS:2.x,3.x,4.x,5.x,6.0,6.2,6.21,6.22
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft MS-DOS operating system versions 2.11, 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 5.0a, 6.0, 6.2, 6.21, 6.22 
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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

Additional query words: 6.22 2.x 3.x 4.x 5.00 5.00a 6.00 6.20

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Keywords          :  
Technology        : kbMSDOSSearch kbMSDOS321 kbMSDOS400 kbMSDOS320 kbMSDOS330a kbMSDOS621 kbMSDOS622 kbMSDOS620 kbMSDOS600 kbMSDOS310 kbMSDOS500 kbMSDOS330 kbMSDOS401 kbMSDOS500a kbMSDOS211
Version           : MS-DOS:2.x,3.x,4.x,5.x,6.0,6.2,6.21,6.22

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