Tip 77: Determining the Amount of RAM Installed in a Computer

May 8, 1995

Abstract

You can use the Windows® application programming interface (API) MemManInfo function to determine how much random access memory (RAM) is installed in the computer system. This article explains how to retrieve the amount of RAM.

How Much Memory Do You Have?

The Windows® application programming interface (API) MemManInfo function can be called to determine how much random access memory (RAM) is installed in your computer. This function is included in the TOOLHELP.DLL file.

To use the MemManInfo function in a Visual Basic® application, you must declare the function as follows:

Private Declare Function MemManInfo% Lib "Toolhelp.dll" (lpmmi As TagMemManInfo)

The MemManInfo function takes only one argument: a structure that will hold information about the memory manager. The number of pages of memory is stored in the wPageSize field of this structure. We need only multiply the number of pages found by a value of 4 to calculate how much RAM is installed.

Example Program

The example program below shows how to retrieve the amount of RAM installed in the computer system.

1. Create a new project in Visual Basic. Form1 is created by default.
   
   
2. Add the following code to the Form_Load event for Form1:

   Private Sub Form_Load()
       Dim R As Long
       Text1.Text = "Total RAM installed: "
       R = GetRAMSize
       Text1.Text = Text1.Text + Str(R)
       
   End Sub
   

3. Add a new module to the project. Module.Bas is created by default.
   
   
4. Add the following code to the Module.Bas file:

   Type TagMemManInfo
       dwSize As Long
       dwLargestFreeBlock As Long
       dwMaxPagesAvailable As Long
       dwMaxPagesLockable As Long
       dwTotalLinearSpace As Long
       dwTotalUnlockedPages As Long
       dwFreePages As Long
       dwTotalPages As Long
       dwFreeLinearSpace As Long
       wPageSize As Integer
   End Type
   Private Declare Function MemManInfo% Lib "Toolhelp.dll" (lpmmi As TagMemManInfo)
   Function GetRAMSize() As Long
       Dim mmi As TagMemManInfo
       mmi.dwSize = Len(mmi)
       x% = MemManInfo(mmi)
       If x% <> 0 Then
           GetRAMSize = mmi.dwTotalPages * 4
       Else
           GetRAMSize = 0
       End If
   End Function
   

5. Add a Text Box control to Form1. Text1 is created by default.

Additional References

"Windows Questions and Answers." (MSDN Library Archive, Books and Periodicals, Microsoft Systems Journal, 1994 Volume 9, March 1994 Number 3)

"FREEMEM2: Displays System Memory Information." (MSDN Library Archive, Sample Code, Book and Periodical Samples, Microsoft Systems Journal Samples, 1994 Volume 9)