Win32::SystemInfo - Memory and Processor information on Win32 systems


    use Win32::SystemInfo;

# Get Memory Information

    my %mHash;
    if (Win32::SystemInfo::MemoryStatus(%mHash))
     ...process results...

    To get specific values:
    my %mHash = (TotalPhys => 0, AvailPhys => 0);
    if (Win32::SystemInfo::MemoryStatus(%mHash))
     ...mHash contains only TotalPhys and AvailPhys values...

    Change the default return value:

# Get Processor Information

    # This usage is considered deprecated
    my $proc = Win32::SystemInfo::ProcessorInfo();

    my %phash;
    for (my $i = 0; $i < $phash{NumProcessors}; $i++) {
     print "Speed of processor $i: " . $phash{"Processor$i"}{MHZ} . "MHz\n";


With this module you can get total/free memory on Win32 systems, including installed RAM (physical memory) and page file. This module will also let you access processor information, including processor family (386,486,etc), speed, name, vendor, and revision information.




   %mHash                      - The hash that will receive the results.
                                 Certain values can be set prior to the
                                 call to retrieve a subset. (See below)
   $format                     - Optional parameter. Used to set the order
                                 of magnitude of the results. (See below)

   Determines the current memory status of a Win32 machine. Populates
   %mHash with the results. Function returns undef on failure.

   Values returned through the hash:
   MemLoad                     - Windows NT 3.1 to 4.0: The percentage of
                                 approximately the last 1000 pages of physical
                                 memory that is in use.
                               - Windows 2000 and later: The approximate percentage of
                                 total physical memory that is in use.
   TotalPhys                   - Total amount of physical memory (RAM).
                               - For Windows 2k and earlier, see CAVEATS below about 
                               - the accuracy of this value.
   AvailPhys                   - Available physical memory (RAM).
   TotalPage                   - Allocated size of page (swap) file.
   AvailPage                   - Available page file memory.
   TotalVirtual                - Total physical + maximum page file.
   AvailVirtual                 - Total amount of available memory.

   Values returned through the hash can also be specified by setting
   them before the function is called.
       my %mHash = (TotalPhys => 0);

   Will return only the total physical memory.

   MemoryStatus return values in bytes by default. This can be changed with
   the $format parameter. Valid values for $format are:
       B        -  Bytes (default)
       KB       -  Kilobytes
       MB       -  Megabytes
       GB       -  Gigabytes

$proc = Win32::SystemInfo::ProcessorInfo([%pHash]);

   Determines the processor information of a Win32 computer. Returns a "quick"
   value or undef on failure. Can also populate %pHash with detailed information
   on all processors present in the system.

   $proc                        - THIS VALUE HAS BEEN MADE OBSOLETE
                                - FOR WINDOWS NT AND LATER. RELY ON IT
                                - AT YOUR OWN RISK.
                                - Contains a numerical representation of the
                                - processor level for Intel machines. For
                                - example, a Pentium will return 586.
                                - For non-Intel Windows NT systems, the
                                - possible return values are:
                                - x64: AMD64
                                - PPC: PowerPC
                                - MIPS: MIPS architecture
                                - ALPHA: Alpha architecture
                                - UNKNOWN: Unknown architecture

   %pHash                       - Optional parameter. Will be filled with
                                - information about all processors.

   Values returned through hash:
   NumProcessors                - The number of processors installed
   ProcessorN                   - A hash containing all info for processor N

   Each ProcessorN hash contains the values:
   Identifier                   - The identifier string for the processor
                                - as found in the registry. The computer I'm
                                - currently using returns the string
                                - "x86 Family 6 Model 7 Stepping 3"
   VendorIdentifier             - The vendor name of the processor
   MHZ                          - The speed in MHz of the processor
                                - This is not a calculated value, but the value
                                - that is recorded in the Windows registry.
                                - This value will be -1 for pre Windows NT
                                - systems (95/98/Me). 
   ProcessorName                - The name of the processor, such as
                                - "Intel Pentium", or "AMD Athlon".

   PLEASE read the note about the MHz value in Caveats, below.

No functions are exported.


Installation is simple. Follow these steps:

 perl Makefile.PL
 nmake test
 nmake install

Copy the SystemInfo.html file into whatever directory you keep your documentation in. I haven't figured out yet how to automatically copy it over, sorry.

Nmake can be downloaded from Alternatively, Strawberry Perl includes dmake that can be used instead.

This module can also be used by simply placing it /Win32 directory somewhere in @INC.

This module requires

Win32::API by Aldo Calpini

Win32::TieRegistry by Tye McQueen


The information returned by the MemoryStatus function is volatile. There is no guarantee that two sequential calls to this function will return the same information.

On 32 bit computers with more than 4 GB of memory, the MemoryStatus function can return incorrect information. Windows 2000 reports a value of -1 to indicate an overflow. Earlier versions of Windows NT report a value that is the real amount of memory, modulo 4 GB.

On 32 bit Intel x86 computers with more than 2 GB and less than 4 GB of memory, the MemoryStatus function will always return 2 GB for TotalPhys. Similarly, if the total available memory is between 2 and 4 GB, AvailPhys will be rounded down to 2 GB.

64 bit systems using 64 bit versions of Perl will report the correct amount of physical memory.

ProcessorInfo will only return the CPU speed that is reported in the Windows registry. This module used to include a DLL that performed a CPU speed calculation, but all of these new-fangled processors caused the code to break. I don't have the time or energy to rewrite the module so that it will play well with Dual Core, Hyperthreading, and what else. The value from the registry appears to be accurate on the machines I've tested this module on. Windows 9x/Me will return values of -1 for processor speed, as their registries don't store the MHz value. If you're using Win9x/Me and need the MHz value, use an older version of this module. Sorry.

The ProcessorName value is also pulled straight from the registry. Correctly determining the processor's name requires throwing some assembly at it, and if you've read the previous paragraph you'll know that DLL that threw assembly at the processor has been removed from this module.

All feedback on other configurations is greatly welcomed.


 0.01 - Initial Release
 0.02 - Fixed CPU speed reporting for Win9x. Module now includes a DLL that
        performs the Win9x CPU speed determination.
 0.03 - Fixed warning "use of uninitialized value" when calling MemoryStatus
        with no size argument.
 0.04 - Fixed "GetValue" error when calling ProcessorInfo as non-admin user
        on WindowsNT
        - Fixed documentation bug: "AvailableVirtual" to "AvailVirtual"
 0.05 - Fixed bug introduced in 0.03 where $format was ignored in
        MemoryStatus. All results were returned in bytes regardless of
        $format parameter.
 0.06 - Added new entry to processor information hash to display the name
        of the processor. WindowsNT and 2K now use the DLL to determine
        CPU speed as well.
 0.07 - Changed contact information. Recompiled DLL to remove some extraneous calls.
 0.08 - Added more definitions for recent CPUs. Added dependency on version 0.40
        of Win32::API. Reworked Win32::API calls. Changed calls in DLL to
        eliminate need to pack and unpack arguments.
 0.09 - Eliminated cpuspd.dll. Should eliminate some of the headaches associated with
        using this module. It should now return CPU info for all flavors of 
        Windows past Win9x without crashing.
 0.10 - Added bug description for Perl Development Kit. Fixed link to ActiveState module
 0.11 - Suppress warnings that come from Win32::API when running with the -w switch. Fix bug
        ( where memory could grow 
 0.12 - Fix some 64 bit related bugs. Use correct SYSTEM_INFO structure 
        ( and use correct struct size


For versions 0.09 and forward, there is a compatibility bug with ActiveState's Perl Development Kit version 6. Apparently the PDK has been designed to expect the cpuspd.dll file to be present and fails against versions of this module that do not include the DLL anymore. For details on the bug and workaround instructions, see this URL:


This man page documents Win32::SystemInfo version 0.12

February 17, 2013.


Chad Johnston <>


Copyright (C) 2013 by Chad Johnston. All rights reserved.


This package is free software; you can redistribute it and/or modify it under the same terms as Perl itself.



Win32 Win32/Utilities