DOS is limited to 640kb low memory, as more device drivers are loaded that space is used up leaving less available memory for applications. This setting loads the DOS command processor into high memory, freeing some low memory for other applications.

Open the CONFIG.SYS file found in the root directory of your C: drive using Notepad or another text editor (not Microsoft Word or any word processor).

Add a new line with the text "DOS=HIGH,UMB", or modify the exiting line beginning with "DOS=" and change it to "DOS=HIGH,UMB" to load the DOS processor into high memory.

Make sure the following lines also exist at the top of the file, without them DOS can not be loaded into upper memory.

DEVICE=C:\WINDOWS\HIMEM.SYS
DEVICE=C:\WINDOWS\EMM386.EXE NOEMS

These changes will take place on the next reboot.

Disclaimer: Modifying the registry can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from modifications to the registry can be solved. Use the information provided at your own risk.