Summarize this article in one sentence.
DOSBox is a free MS-DOS emulator that can run your old DOS programs in Windows. If you run old DOS programs through the Command Prompt and want to display them full-screen, DOSBox is the easiest way to do that. This is especially useful for old games. Because DOSBox is focused on games, it has limited networking and printing support. In theory, however, it should be able to run any DOS program. You can download the DOSBox installer for free from dosbox.com/wiki/Releases. Run the installer after downloading, and follow the prompts to install DOSBox. During installation, choose a location at the root of your hard drive. For example, if your hard drive is "C:\", install DOSBox at C:\DOSBox. DOSBox will use this folder to act as its own "C:\" drive. Place this folder in the same location that your DOSBox folder is located. Name the folder something easy to access and remember, such as C:\DOSPrograms or C:\oldgames. Each program should be contained within a separate folder in your programs folder. You'll be taken to the DOSBox command line, and will need to configure a few things before you can start using it. Type MOUNT C C:\DOSPrograms and press ↵ Enter. Replace C:\DOSPrograms with the folder you created for your DOS programs. If you're running a program from a CD, type MOUNT D D:\ -t cdrom to mount the CD drive instead. Type cd folderName to open the program's folder. Replace folderName with the name of the folder for the program you want to run. Type dir to see a list of files in the directory. Find the EXE file and type it into the command line. This will start the DOS program. Once you've got the program running, you can switch to full-screen mode by pressing Alt+↵ Enter.
Understand the process. Download and install DOSBox. Create a folder for your programs. Add your old programs to this folder. Launch DOSBox. Mount the programs folder. Open the folder for the program you want to run. Start the program. Switch to full-screen.