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

* VB-CODE (3)

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." (Books and Periodicals, Microsoft
 Systems Journal, 1994 Volume 9, March 1994 Number 3)
"FREEMEM2: Displays System Memory Information."  (Sample Code, Book
 and Periodical Samples, Microsoft Systems Journal Samples,
 1994 Volume 9)