johnp999,

You cannot add available memory and system cache to attempt to determine total physical memory. See the decriptions of these values here.

A more meaningful number in task manager is the Commit/Charge: value at the lower right. The numerator indicates the amount of memory in use, the denominator shows the total amount of memory (physical and virtual) available. When the numerator exceeds the amount of physical memory in the system, slower virtual (paged) memory is used. The 40% value you cite may apply to Windows 9X systems and to 40% of resources. The architecture of Windows XP makes all installed memory available to applications (not limiting resources to 64K) so it is not a valid concern.

I am not sure that they should add up the way you suppose. I have 1024MB RAM. Under physical memory, total, this is reported as 1047552  (=1023MB).

On restart, the sum of available and system cache is usually significantly less (~645000 available (i.e.~629 MB), + ~370000 System cache =1015000). But after using the PC for a while, opening, closing apps, etc, whilst the available memory when apps are closed reverts more or less to its starting value, the system cache increases continually and the sum exceeds 1047552, e.g. it gets up to 1120000 or more; presumably part of the system cache is in the page file. Remember that XP puts much of the OS functions in memory if that is available, but gracefully releases it when memory is needed by apps.

Thanks Denny .. appreciate you being here..

So much better than talking to India  :smileywink:

523260/1024=511MB. It is not unusual for about 1MB to be unavailable, it is used by very basic parts