Holy cow, I wrote a book!
During Windows 95 beta testing, people ran the System Properties page and complained
about "missing memory".
The Windows 95 System Properties page reports the amount of memory available to Windows
as system memory, which is not necessarily the same as the amount of memory installed
in your computer.
For example, you may have an old DOS device driver that allocates a large amount of
memory for itself, which prevents Windows 95 from using it. Or you may have a dreaded
UMA machine, where your so-called 8MB of memory is actually being divided between
main system memory and video memory. So if you have an 8MB UMA machine and you're
running at 800x600 8bpp, you actually have only 7.5MB of memory, since the other half-meg
got eaten by the video card.
When we displayed the actual amount of memory available to Windows, we got lots of
bug reports from people asking, "I paid for 8MB of memory, where is it?"