Specifying Amount of RAM Available to Windows Using MaxPhysPage
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The information in this article applies to:
Microsoft Windows Millennium Edition
Microsoft Windows 95
Microsoft Windows 98
------------------------------------------------------------
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....s/hardware/hwddresctr.asp
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
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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: Q134503
TITLE : Parity Error Messages May Indicate Bad Memory
===========================================================
Here's another:
"Out of Memory" Error Messages with Large Amounts of RAM Installed
------------------------------------------------------------
The information in this article applies to:
Microsoft Windows Millennium Edition
Microsoft Windows 98 Second Edition
Microsoft Windows 98
Microsoft Windows 95
------------------------------------------------------------
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....s/hardware/hwddresctr.asp
SYMPTOMS
If a computer that is running any of the versions of Windows that are listed
above contains more than 512 megabytes (for example, 768 megabytes) of
physical memory (RAM), you may experience one or more of the following
symptoms:
You may be unable to open an MS-DOS session (or command prompt) while
Windows is running. Attempts to do so may generate the following error
message:
There is not enough memory available to run this program.
Quit one or more programs, and then try again.
The computer may stop responding (hang) while Windows is starting, or halt
and display the following error message:
Insufficient memory to initialize windows. Quit one or more memory-resident
programs or remove unnecessary utilities from your Config.sys and
Autoexec.bat files, and restart your computer.
CAUSE
The Windows 32-bit protected-mode cache driver (Vcache) determines the
maximum cache size based on the amount of RAM that is present when Windows
starts. Vcache then reserves enough memory addresses to permit it to access
a cache of the maximum size so that it can increase the cache to that size
if needed. These addresses are allocated in a range of virtual addresses
from 0xC0000000 through 0xFFFFFFFF (3 to 4 gigabytes) known as the system
arena.
On computers with large amounts of RAM, the maximum cache size can be large
enough that Vcache consumes all of the addresses in the system arena,
leaving no virtual memory addresses available for other functions such as
opening an MS-DOS prompt (creating a new virtual machine).
WORKAROUND
To work around this problem, use one of the following methods:
Use the MaxFileCache setting in the System.ini file to reduce the maximum
amount of memory that Vcache uses to 512 megabytes (524,288 KB) or less.
For additional information about how to use the MaxFileCache setting, click
the article number below to view the article in the Microsoft Knowledge
Base:
Q108079 32-Bit File Access Maximum Cache Size
Use the System Configuration utility to limit the amount of memory that
Windows uses to 512 megabytes (MB) or less.
For additional information about how to use the System Configuration
utility, click the article number below to view the article in the Microsoft
Knowledge Base:
Q181966 System Configuration Utility Advanced Troubleshooting Settings
Reduce the amount of memory that is installed in your computer to 512 MB or
less.
STATUS
Microsoft has confirmed this to be a problem in the Microsoft products that
are listed at the beginning of this article.
MORE INFORMATION
Vcache is limited internally to a maximum cache size of 800 MB.
This problem may occur more readily with Advanced Graphics Port (AGP) video
adapters because the AGP aperture is also mapped to addresses in the system
arena. For example, if Vcache is using a maximum cache size of 800 MB and an
AGP video adapter has a 128-MB aperture mapped, there is very little address
space remaining for the other system code and data that must occupy this
range of virtual addresses.
