How to Increase Conventional Memory for MS-DOS-Based Programs

This article was previously published under Q134399
This article has been archived. It is offered "as is" and will no longer be updated.
This article describes how to increase the amount of conventional memoryavailable for MS-DOS-based programs in Windows. The following topicsare discussed:
  • Determining current memory conditions.
  • Making more conventional memory available.
MS-DOS-based programs require a certain amount of conventional memory torun, even when you run them in Windows. If you attempt to run anMS-DOS-based program that requires more conventional memory than iscurrently available on your computer, the program may not run correctlyor at all, and an error message indicating that there is insufficientmemory to run the program may be displayed. When this occurs, you mustreconfigure your computer so that more conventional memory is available.

Determining Current Memory Conditions

To determine how much conventional memory is currently available forMS-DOS-based programs, type the following command at a command prompt,press ENTER, and then view the value on the Largest Executable ProgramSize line:
mem /c
If the value on the Largest Executable Program Size line is smaller thanthe amount of conventional memory required by the MS-DOS-based program youare trying to run, the program may not run correctly or at all until youreconfigure your computer. To determine how much conventional memory aparticular MS-DOS-based program requires, consult the documentationincluded with the program, or contact the program's manufacturer.

Making More Conventional Memory Available

Device drivers and memory-resident programs that load from the Config.sysand Autoexec.bat files can reduce the amount of conventional memoryavailable for MS-DOS-based programs. Increasing the amount of conventionalmemory that is available for MS-DOS-based programs typically involvesremoving unnecessary drivers and programs from the Config.sys orAutoexec.bat files, replacing real-mode drivers in the Config.sys filewith protected-mode versions, or loading drivers and programs into uppermemory instead of conventional memory.

Removing Unnecessary Drivers and Programs:

To determine if a particular driver or memory-resident program in theConfig.sys or Autoexec.bat file is required for your computer to functionproperly, consult the documentation included with the program or devicethat installed the driver or memory-resident program, or contact theprogram or device's manufacturer.

If you are not sure which program or device installed a particular driveror memory-resident program, you can attempt to determine if the driver orprogram is necessary by temporarily disabling the corresponding line inthe Config.sys or Autoexec.bat file. If your computer, the devicesinstalled on your computer, and the programs you run on your computerall seem to function properly after you disable a line, the driver ormemory-resident program may not be necessary.

NOTE: Before you modify the Config.sys or Autoexec.bat files, you should make backup copies of the files. Do not remove any hard disk drivers, disk partitioning drivers, or disk compression drivers while you are attempting to determine if the drivers and programs in your Config.sys or Autoexec.bat files are necessary. For information about specific driversthat should not be removed, please see chapter 35 of the Microsoft Windows95 Resource Kit.

Replacing Real-Mode Drivers with Protected-Mode Versions:

Windows includes protected-mode drivers for many devices. In addition,many hardware manufacturers provide protected-mode drivers for theirdevices. To attempt to install a Windows protected-mode driver for adevice installed on your computer, follow these steps:
  1. In Control Panel, double-click Add New Hardware.
  2. Click Next, verify that Yes (Recommended) is selected, click Next, and then click Next again.
If the Add New Hardware Wizard does not detect the device and install aprotected-mode driver for it, you can attempt to install a Windowsprotected-mode driver for the device manually. To do so, follow thesesteps:
  1. In Control Panel, double-click Add New Hardware.
  2. Click Next, click No, and then click Next.
  3. Click the type of device for which you are attempting to install a protected-mode driver in the Hardware Types box, and then click Next.
  4. Click the manufacturer of the device in the Manufacturers box. If the specific device appears in the Models box, click the device, and then click OK to install the protected-mode driver. If the manufacturer of the device does not appear in the Manufacturers box, or the specific device does not appear in the Models box, Windows does not include a protected-mode driver for the device.
To determine if the hardware's manufacturer provides a protected-modedriver for the device, contact the device's manufacturer.

Loading Drivers and Programs into Upper Memory:

To attempt to load one or more drivers or memory resident programs fromthe Config.sys or Autoexec.bat files into upper memory, make sure that theConfig.sys file contains lines similar to the following lines (in thefollowing order):
   device=c:\windows\himem.sys   device=c:\windows\emm386.exe noems   dos=high,umb   devicehigh=c:\windows\command\drvspace.sys /move				

Then, try loading device drivers in the Config.sys file using theDEVICEHIGH command instead of the DEVICE command. In addition, tryloading memory-resident programs in the Autoexec.bat file using theLOADHIGH command.

NOTE: If your computer is configured so that expanded memory is availableand you are loading the Mscdex.exe file from the Autoexec.bat file, youcan attempt to load part of the Mscdex.exe file into expanded memory usingthe /E switch on the Mscdex.exe command line.
For additional information about increasing the amount of conventionalmemory that is available for MS-DOS-based programs in Windows, pleasesee the following articles in the Microsoft Knowledge Base:
TITLE : A General Tutorial on the Various Forms of Memory

TITLE : Optimizing Your Use of Upper Memory Blocks

TITLE : Command-Line Switches for MSCDEX.EXE

Article ID: 134399 - Last Review: 12/04/2015 11:46:36 - Revision: 2.2

Microsoft Windows 95, Microsoft Windows 95, Microsoft Windows 95, Microsoft Windows 98 Standard Edition, Microsoft Windows 98 Second Edition

  • kbnosurvey kbarchive kbhowto kbenv kbfaq KB134399