The Basics of Computer Memory
Computer memory is a storage area for both program code and data which is currently in
use. Computer programs can write and retrieve information from
memory in any order, allowing for fast data retrieval and manipulation.
Computer memory is called Random Access Memory (RAM).
Data in RAM can be accessed randomly rather than sequentially.
This means that data can be accessed from different locations at the
same speed. Other storage media like CD-Rom and hard drives have
to wait for the drive to spin to the correct location before data can
be accessed.
Because of the fast access time that RAM offers, installing more RAM
in your computer will make it significantly faster. This is
because the computer can put more program instructions into memory and
rely less on information stored on the slower hard drive.
Increasing the amount of memory is one of the best ways of improving
computer performance. If you compare two computer systems
identical except for the amount of RAM, the one with the greater amount
of memory will be faster.
How Much RAM?
So if more RAM is better, how much is the best? The simple
answer to that question is: As much as possible. In the real 
world, though, once you reach a certain threshold you are likely to see diminishing returns on your memory investment.
Think of 512 Megabytes (MB) as the standard for a computer with the
Windows XP operating system. The Linux operating system requires
significantly less. Linux has several advantages over Windows
(free, more stable) but for the most part remains on the
sidelines. Most PCs today use Windows.
With 512 MB of memory, you should be able to comfortably run several
applications at the same time (multi-task). You can surf the
Internet, download MP3s, run a word processor and check your email
without any noticeable sluggishness.
Some applications are more memory hungry than others, however, so if
you notice your computer slowing down, you might consider adding more
memory. Before going that route however, try defragmenting your
hard drive. A fragmented hard drive is another major cause of
slow performance.
Types of RAM
DDR SDRAM is currently the most popular type of memory module. DDR stands for Double Data Rate and means that the memory can be accessed two times per clock cycle. SDRAM stands for Synchronous Data Random Access Memory which has been the standard for memory modules for close to 10 years now.
If you wish to add more memory to your computer, you must buy
modules with the correct contact layout. The most common form
factors are 168 pin, 184 pin and 200 pin. It is essential that
you know which type your motherboard accepts before buying new memory.
You also need to know if there are free slots on you motherboard for
accepting new memory modules. If all the slots are used you will
have to replace one or all of the current modules for higher capacity
ones. If there is at least one free slot you can just buy a new
memory module and insert it in the empty slot.
Careful though. Some motherboards are designed to accept both
SDRAM and DDR SDRAM but the two types cannot be mixed – you have to use
all SDRAM or all DDR SDRAM. Check the motherboard manual to see exactly what kind of memory you can use.
