"I can assure you that data processing is a fad that won't last the year." - Chief Business Editor, Prentice Hall, 1957
AMD Athlon: 1655 43.0%
Intel Pentium III: 917 23.8%
Intel Pentium 4: 807 21.0%
Intel Celeron: 181 4.71%
AMD Duron: 172 4.47%
Other: 110 2.86%
RAM
One of the most common types of ram in a computer is Random Access Memory,
or RAM. This memory is considered random access because the computer can
access any part of the memory whenever it wants, which means that it is not
restricted to go in any certain order.
Just like any other part of a computer, memory is a circuit which is made of
millions of transistors and capacitors. In computer memory, every
capacitor is paired up with a transistor. The capacitor holds the
information, while the transistor is used to access or change the information
that the capacitor is holding. To store a 1 in the capacitor, it is filled
up with electrons. To store a 0 in the capacitor, it is emptied so that
there are no electrons in it. This is all done at a very rapid pace, so
that the computer can process the information as quickly as possible.
Memory Cells
Memory cells hold the information, but how is this achieved?
Well, they are arranged on a 2 dimensional array. To change the state of a cell
from 0 to 1, the column and row of that cell are charged, and the capacitor gets
filled where the column and row meet, which is where the capacitor is located.
Similarly, to chance the state of a cell from 0 to 1, the column and row are charged,
in order to open a circuit, allowing the electrons to escape from the capacitor. To
help you understand this a little better, here is an interactive activity where
you get to choose which capacitor will hold a binary 1, and which will hold a
binary 0. Click on any one of the circles to make the capacitor hold a binary 1.
Click on the same circle again to make it hold a binary 0.
I will use the Capacitor in row A, column 1 to explain. When you click on it the
first time, row A is charged up, and column 1 is charged up. Only the point of
intersection between the charged row and column becomes a 1. When the same row and
column become charged up again, the capacitor releases the electrons, and now holds
a binary 0. The other capacitors which are in that row or column remain unchanged.
Common Types of Ram in a Computer
Although all computers have RAM, the type of RAM that they have can change
from computer to computer. The type of RAM used can vary depending on one
of these factors:
the performance the computer needs
type of RAM the computer can support
speed of the system bus
type of budget the Computer is built for
Keeping this in mind, here are some of the most common types of RAM in
PCs.
EDO-RAM
A type of RAM which does not wait to process one bit before
going to the next. This RAM is not used for newer computers, although
it is in many Pentium II or lower class computers.
SD-RAM
RAM which replaced EDO-RAM in order to increase speed.
At the same clock rate, it is almost the same speed as EDO-RAM. It was
supposed to be faster because it uses burst mode to read data. This
basically means that after it read the data the CPU required, it continued
reading data after this in anticipation that the CPU will need the next
piece of data in the memory right after the current data is processed.
It is somewhat effective, but the faster clock frequency is what really
makes it reach better performance.
RD-RAM
A type of RAM developed to operate much differently than
other RAM types. Rambus created its own high-speed data bus, Rambus
Channel, and made the RAM work in parallel (have more than one stream of
information coming from the chip) in order to achieve phenomenal clock
speeds compared to the competition. In reality, it is actually slower
and more expensive than SD-RAM, which is a topic to be discussed later in
the memory section.
Although RAM is used in computers, it is not limited only to them. For
example, most health cards in the developed world have RAM to keep the
cardholder's health information. TVs, Radios and even some Microwaves have
RAM in order to keep custom information, such as favourite radio stations.
43.0% 
