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DADDY BOB'S COMPUTER Q & A
September 2,
2007
Q.
I recently bought a new computer and paid
for 4 GB Memory. When I open the System
Properties, it says I only have 3 GB. Have I
been cheated?
A.
Well, yes in a way but not by your computer
manufacturer and not by Microsoft or any
other company. You have been cheated out of
about 1 GB of useable memory by simple
mathematics. Well, maybe not so simple, so
I'll try to explain. (Note: This got
larger than I anticipated when I started.)
Most
likely, you are using a 32 bit computer
running a 32 bit operating system. 32 bits
has the mathematical limit of only being
able to address (see, use, access) 4 GB of
memory. Here's an experiment to try that
will show this to you. Since this will get a
little involved, you can click
HERE
to print out this article to make it
easier to follow.
Click
Start, then Run, and enter calc and click
OK. When the calculator opens, click View,
and select Scientific. Now, click the dot in
front of Bin to put the calculator in Binary
mode. From the keyboard, enter a 1 followed
by 32 zeros. That's equivalent to 32 bits in
binary.
Now,
click the dot in front of Dec to convert
that binary number to a decimal format that
you are probably more familiar with. You
should get 4294967296, the equivalent number
of bytes in 32 Bits. Now, divide this number
by 1024 and you get 4194304, the equivalent
number of KB (Kilobytes). Divide again by
1024 and you get 4096, the equivalent number
of MB (Megabytes). Divide by 1024 one more
time and you get 4, the equivalent number of
GB (Gigabytes).
So, you
see the largest number of bytes or locations
in 32 bits is 42,949,672,964 bytes,
4,194,304 KB, 4,096 MB or 4 GB.
In order
for the computer and operating system to
work, it has to be able to see, access or
address information, and this information
must be in this 4 GB address space. So, the
operating system just automatically
allocates address space for this purpose,
and it has top priority so gets its before
anything else.
The
amount it allocates depends on how much
actual memory is installed and the software,
devices, etc., that are installed. In your
case, it appears to be about 1 GB has been
allocated. Your computer most likely has the
4 GB of memory you paid for installed, but
there is only 3 GB available because the
operating system needs and has allocated
about 1 GB of address space to itself.
Your
video card may be allocated the biggest part
of this address space. Although most video
cards have their own memory integrated on
the card and don't actually use the
computers RAM, the address space must be in
the 4 GB limit the 32 bit operating system
can address.
If you
are still with me and want to see what more
this memory is being allocated to, try this.
Right click My Computer and select Manage.
Double click on Services and Applications,
and then double click on Services. All the
items listed that show the Status to be
started have memory addresses allocated to
them.
Close out
everything and get back to the desktop.
Click Start, Programs, Accessories, System
Tools, and System Information. Click the +
in front of Hardware Resources and select
I/O. All the numbers listed under Resources
are memory addresses that have been
allocated.
One more
place. Go to
C:\Windows\System32\Drivers. There you
will find a list of the drivers that you
system is using. Probably not all at the
same time, but address space must be
provided for them when they are needed.
I could
go on and on, but by now you should get the
idea. So, what is the answer to this
addressable memory limitation? For your next
computer be sure you get one that supports a
64 Bit operating system. Windows XP and
Vista both have 64 bit versions available
now. It is anticipated that the next version
of Windows will only come in 64 bit
versions.
Mathematically, a 64-bit operating system
can access 16 exabytes of address space.
That’s 4 billion times the 32-bit system
limit, give or take a little.
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