KB181862 - Specifying Amount of RAM Available to Windows Using MaxPhysPage

Article ID: 181862

Article Last Modified on 1/22/2007

Microsoft Windows Millennium Edition
Microsoft Windows 95
Microsoft Windows 98 Standard Edition

This article was previously published under Q181862

If this article does not describe your hardware-related issue, please see the following Microsoft Web site to view more articles about hardware:

http://support.microsoft.com/default.aspx/w98?sid=460

SUMMARY

This article contains a table of MaxPhysPage values you can use to limit the amount of random access memory (RAM) available to Windows.

MORE INFORMATION

To use the MaxPhysPage entry to specify the amount of RAM that is available to Windows, add the following line in the [386Enh] section of the System.ini file

   MaxPhysPage=<nnn>

where <nnn> is a hexidecimal number that determines the number of memory pages available to Windows. A page is 4096 bytes of RAM for 486 and Pentium processors.

When the MaxPhysPage entry is used, the following formula is used to determine the amount of RAM available to Windows:

   4096 X MaxPhysPage (decimal) = Amount of RAM available to Windows in bytes

Therefore, to limit Windows to 32 MB of memory, use the following formula to determine the MaxPhysPage entry:

   (32 * 1048576) / 4096 = 8192 (decimal) or 02000 (hexadecimal)

NOTE: One megabyte is 1,048,576 bytes.

The following table list some common RAM amounts and the corresponding MaxPhysPage entry:

   Amount of RAM
   available to Windows (MB)  (Bytes)           MaxPhysPage entry
   --------------------------------------------------------------
   960                        1,006,632,960     MaxPhysPage=3C000
   896                          939,524,096     MaxPhysPage=38000
   832                          872,415,323     MaxPhysPage=34000
   768                          805,306,368     MaxPhysPage=30000
   704                          738,197,504     MaxPhysPage=2C000
   640                          671,088,640     MaxPhysPage=28000
   576                          603,979,776     MaxPhysPage=24000
   512                          536,870,912     MaxPhysPage=20000
   448                          469,762,048     MaxPhysPage=1C000
   384                          402,653,184     MaxPhysPage=18000
   320                          335,544,320     MaxPhysPage=14000
   256                          268,435,456     MaxPhysPage=10000
   224                          234,881,024     MaxPhysPage=0E000
   192                          201,326,592     MaxPhysPage=0C000
   160                          167,772,160     MaxPhysPage=0A000
   128                          134,217,728     MaxPhysPage=08000
    96                          100,663,296     MaxPhysPage=06000
    88                           92,274,688     MaxPhysPage=05800
    80                           83,886,080     MaxPhysPage=05000
    72                           75,497,472     MaxPhysPage=04800
    64                           67,108,864     MaxPhysPage=04000
    56                           58,720,256     MaxPhysPage=03800
    48                           50,331,648     MaxPhysPage=03000
    40                           41,943,040     MaxPhysPage=02800
    32                           33,554,432     MaxPhysPage=02000
    24                           25,165,824     MaxPhysPage=01800
    16                           16,777,216     MaxPhysPage=01000
    12                           12,582,912     MaxPhysPage=00C00
    08                            8,388,608     MaxPhysPage=00800

For additional information about MaxPhysPage, please see the following Articles in the Microsoft Knowledge Base:

Article-ID: 134503
TITLE : Parity Error Messages May Indicate Bad Memory

Article-ID: Q83436 83436
Title : Windows 3.1 Resource Kit SYSTEM.INI [386ENH] Section M-Z

Additional query words: HWMEM how to

Keywords: kbdiskmemory kbenv kbhowto KB181862