Wednesday, April 25, 2012

How to install MS-DOS 6.22 under VMWare ESX part 2

Once you have gone through the first post which explained how to install MS-DOS in a virtual machine, you should immediately see the processor of the VM spike up and stay at 100% usage all the time. At this moment the ESX also is suffering from MS-DOS being unable to idle its CPU activity.

Processor activity for a MS-DOS virtual machine just after installation

ESX processor being overloaded by the MS-DOS virtual machine

The solution to this evident incompatibility resides in a small file named dosidle.exe. This file can be easily found on the Internet. Once you have it, use WinImage to make a flp disk image and inject this file in it. The others file are unnecessary so don't copy them. Mount the flp image and copy the executable to the C: drive with the following command (it's case insensitive, as it always was in Microsoft world):


Then edit the autoexec.bat and add this line at the end of it:


Dosidle.exe configuration and initialization
Reboot the VM or just run C:\DOSIDLE.EXE. You will see the CPU usage dramatically dropping.

No further action is required to solve this issue.

I hope this post helped. Stay tuned for more about running MS-DOS and Windows 3.1 in a virtual machine.


  1. Thank YOU very much! IMG files are the same as FLP, just rename them and You don't need to have troubles with "converting" them ;)

  2. Thanks for sharing this information!


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