CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

2.5. Running MS-DOS–Based Applications

MS-DOS–based applications represent the oldest type of applications you are likely to run on your computer. MS-DOS applications are supported by Windows XP. MS-DOS–based applications have always been designed to run alone on a computer. They expect to be the only application ever running on that PC, and as such expect to see certain things, like no Windows presence. Microsoft uses virtual machines to provide a unique environment for these applications. These virtual machines simulate all the hardware that would normally be found in a computer, including

• Keyboard

• Mouse

• Monitor

• COM ports

• RAM

• Disk drives

With all these components being virtualized, an MS-DOS–based application believes that it is running alone in a computer. The virtual computer's settings can be modified through a program information file (PIF), which I discuss in the next section.

2.5.1. Program information file (PIF) settings

Every MS-DOS–based application that executes on your computer starts by configuring a working environment from settings found in a PIF. This is the case even if you are not aware that a PFI file is being used because a _default.pif file on your hard drive is used if no other PIF exists.

If you want to create a default PIF for a specific application, right-click the application and choose Properties. Even though there is not currently a PIF for the application, you will see all the PIF-related tabs, such as Screen, Memory, Font, and Misc. If you make any changes ...