How to Increase the DOS Conventional Memory in a Virtual Machine (825463)

SUMMARY

This article describes how to increase the MS-DOS conventional memory in a virtual machine.

MS-DOS-based programs use some conventional memory to run, even when you run them in Windows. The conventional memory area is the 0K-640K section of memory. MS-DOS and typical program software use this area of memory.

If you try to run an MS-DOS-based program that uses more conventional memory than your computer currently has available, the program may not run correctly or at all. You may also receive an error message that says that there is not sufficient memory to run the program. When this behavior occurs, you must reconfigure your computer so that more conventional memory is available. To do so, edit the Config.sys file.

Note Back up the Config.sys file before you make any changes.

To edit the Config.sys file, use any of the following methods:

• Use a text editor such as Notepad to edit the Config.sys file.
• In Microsoft Windows 98 or Microsoft Windows Millennium Edition, use the sysedit command. To do so, click Start, click Run, type sysedit in the Open box, click OK, and then click C:\Config.sys on the Windows menu.
• In a DOS window, type:

  edit C:\CONFIG.SYS

To edit the Config.sys file to make more conventional memory available, use any of the following methods:

• Add the following lines at the beginning of the text in the CONFIG.SYS file:

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

  Note The RAM switch at the end of the second line permits Expanded Memory Specification (EMS) memory.
• You can set the area of random access memory (RAM) that you want EMS to use. If you do this, you must use an area that nothing else uses. For example, to use a memory address that is reserved for monochrome displays (that are no longer used), use the following lines instead:

  DEVICE=C:\WINDOWS\HIMEM.SYS
  DEVICE=C:\WINDOWS\EMM386.EXE RAM I-B000-B7FF

• If your program requires a particular amount of memory, you can set the EMS size to a fixed amount. If you do not set the EMS size, the program may use more than you want it to use. Typically, it is best practice not to set a fixed size. For example, if a program must use 4 MB of EMS, use the following lines instead:

  DEVICE=C:\WINDOWS\HIMEM.SYS
  DEVICE=C:\WINDOWS\EMM386.EXE 4096

After you make the changes, save the file, and then restart the virtual machine.