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.
This step-by-step article describes how to install Virtual PC DOS Additions for additional functionalities such as Shared Folders in a DOS-based guest PC operating system.
The Virtual PC DOS Additions (Dos Additions.vfd) are included with Virtual PC and are located in the following folder on the Virtual PC CD-ROM:
CD-ROM Drive Letter:\Additions\Dos Additions
To install DOS Additions to a DOS-based guest PC operating system, follow these steps:
Start the DOS-based guest PC operating system, and permit it to finish starting.
In the host operating system, open the Additions\Dos Additions folder.
Drag the Dos Additions.vfd file from the Additions\Dos Additions folder to the floppy disk icon in the lower left corner of the DOS-Virtual PC window.
In the DOS-Virtual PC window, type the following command, and then press ENTER: a:dosadd.bat
After the Dosadd.bat file has completed, you receive the following message:
You have successfully installed the Virtual PC DOS Additions. Please eject the DOS additions floppy image and restart the virtual machine.
The required files are copied, and the required lines are added to your Config.sys and your Autoexec.bat files.
Verify that the Config.sys file contains the following line:
If this line does not appear, edit the Config.sys file to add the line. This adds the Shared Folder functionality to the DOS-based guest PC operating system.
Note For CD-ROM access in a DOS environment, the Mscdex.exe file is also required. For additional information about how to access CD-ROM drive from MS-DOS, click the following article number to view the article in the Microsoft Knowledge Base:
135174 Cannot Access CD-ROM Drive from MS-DOS Mode or Command Prompt
Virtual PC DOS Additions can be installed on any DOS-based guest PC. DOS Additions contains the following files:
Fshare.exe - You can use this utility to enable Shared Folders on your DOS-based guest PC and on the host PC.
Cdrom.sys - A new CD-ROM driver that is designed to work with the emulated CD-ROM drive in Virtual PC.
Idle.com - Virtual PC uses this file to detect when a DOS guest PC is idle (not active). It automatically cycles down CPU usage on the host PC.
Note This functionality is only used on Virtual PC for Windows.
These three files are installed in the Cntx folder on drive C of the guest PC. The Autoexec.bat and the Config.sys files are modified to use these new files.