Toshiba U400 User Manual page 21

Main Memory
Disclaimer
If your computer is configured with two 2 GB memory modules, the
memory might be displayed as approximately 3 GB only (depending on the
computer's hardware specifications).
This is correct because the operating system usually displays the available
memory instead of the physical memory (RAM) built into the computer.
Various system components (like the video adapter's GPU and PCI
devices like Wireless LAN, etc.) require their own memory space. Since a
32-bit operating system cannot address more than 4 GB of memory these
system resources overlap the physical memory. It is a technical limitation
that the overlapped memory is not available to the operating system.
Even though some tools might display the actual physical memory built
into your computer, the memory available to the operating system will still
be approximately 3 GB only.
Video RAM
Power
Battery Pack
RTC Battery
User's Manual
Part of the main system memory may be used by
the graphics system for graphics performance
and therefore reduce the amount of main system
memory available for other computing activities.
The amount of main system memory allocated to
support graphics may vary depending on the
graphics system, applications utilized, system
memory size and other factors. For PC's
configured with 4 GB of system memory, the full
system memory space for computing activities will
be considerably less and will vary by model and
system configuration.
Depending on the model you purchased:
®
Mobile Intel GM965 Express Chipset/Mobile
®
Intel GL960 Express Chipset model: Video RAM
capacity shares with main memory, and the
proportion depends on Dynamic Video Memory
Technology.
Your computer is powered by a rechargeable
lithium-ion battery pack.
The internal RTC battery backs up the Real Time
Clock and calendar.
Introduction
1-3