How to Use a RAM Drive to Troubleshoot Memory

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Microsoft RAMDrive is a memory-resident program that lets you use part of your computer's RAM as if it were a disk drive. By creating a RAM drive that uses most of your computer's physical RAM, you may be able to isolate the memory problem to a particular memory chip. To create a RAM drive using Windows 95, perform the following steps:

1. Restart your computer. When you see the "Starting Windows 95" message, press the F8 key, and then choose Command Prompt Only from the Startup menu.
2. Use any text editor, such as Edit.com, to add the following line to the Config.sys file

   device=<path>\ramdrive.sys <x> /E

   where <path> specifies the location for Ramdrive.sys and <x> is equal to the total amount of RAM (converted from megabytes to kilobytes) minus 4096 (4 megabytes are required for Windows 95 to start). For example, if you installed Windows 95 on drive C in a folder called Windows and your computer has 16 megabytes (MB) of RAM, add the following line:

   device=c:\windows\ramdrive.sys 12288 /E

   The value 12288 is derived from the following formula using the example above:

   (16 * 1024) - 4096 = 12288 bytes

   NOTE: The Ramdrive.sys line must follow the Himem.sys line, or the RAM drive may not function.
   
   NOTE: Windows 95 is limited to a 16-MB RAM drive. For additional information, please see the following article in the Microsoft Knowledge Base:

   126448 Err Msg: Not Enough Extended Memory Available to Start...

3. Save the Config.sys file and then restart your computer normally.
4. If the problems no longer occur, halve the value for <x> in the Config.sys file and restart your computer. Repeat these steps until the problem returns. Once it returns, the faulty RAM is in the area that you most recently removed from the RAM drive. Contact your hardware manufacturer about replacing this memory.
5. If the problems persist, there may be a problem in the memory above the high memory area (HMA) that Ramdrive.sys is not using. To test the memory above the HMA (starting at 1088K), remove Ramdrive.sys from the Config.sys file and add the following line to the Config.sys file

   device=<path>\himem.sys /int15=<x>

   where <path> specifies the location for Himem.sys and <x> is equal to the total amount of RAM you want to exclude from Windows 95's use. For example, the line "device=c:\windows\himem.sys /int15=4096" prevents Windows 95 from using the section of memory from 1088K to 5184K (or roughly the first 4 MB of RAM above conventional memory + the UMA + the HMA). If the problems no longer occur, this memory needs to be replaced.

If you continue to have problems, one of the following situations may exist:

• The problems may be caused by memory within the 1088K of RAM that the RAMdrive and HIMEM statements cannot reserve for Windows 95. To test this, try new memory modules or switch the order of the RAM modules in your computer. If you are unfamiliar with this process, Microsoft recommends that you contact your hardware manufacturer for assistance.
• The problems may be caused by CPU cache RAM. Many new processors implement a method of optimization that uses motherboard and internal CPU cache RAM to increase performance and optimize data and code execution. This cache is used to offset the number of direct reads that are performed against main memory for frequently used data and code.
  
  To test this, disable the internal and external CPU cache. For information on how to do this, please read your hardware documentation or contact your hardware manufacturer.