SRAM: Static random access memory uses multiple transistors, typically
four to six, for each memory cell but doesn't have a capacitor in each
cell. It is used primarily for cache.
DRAM: Dynamic random access memory has memory cells with a paired
transistor and capacitor requiring constant refreshing.
FPM DRAM: Fast page mode dynamic random access memory was the original
form of DRAM. It waits through the entire process of locating a bit of
data by column and row and then reading the bit before it starts on the
next bit. Maximum transfer rate to L2 cache is approximately 176 MBps.
EDO DRAM: Extended data-out dynamic random access memory does not wait
for all of the processing of the first bit before continuing to the next
one. As soon as the address of the first bit is located, EDO DRAM begins
looking for the next bit. It is about five percent faster than FPM.
Maximum transfer rate to L2 cache is approximately 264 MBps.
SDRAM: Synchronous dynamic random access memory takes advantage of the
burst mode concept to greatly improve performance. It does this by
staying on the row containing the requested bit and moving rapidly
through the columns, reading each bit as it goes. The idea is that most
of the time the data needed by the CPU will be in sequence. SDRAM is
about five percent faster than EDO RAM and is the most common form in
desktops today. Maximum transfer rate to L2 cache is approximately 528
DDR SDRAM: Double data rate synchronous dynamic RAM is just like SDRAM
except that is has higher bandwidth, meaning greater speed. Maximum
transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133
RDRAM: Rambus dynamic random access memory is a radical departure from
the previous DRAM architecture. Designed by Rambus, RDRAM uses a Rambus
in-line memory module (RIMM), which is similar in size and pin
configuration to a standard DIMM. What makes RDRAM so different is its
use of a special high-speed data bus called the Rambus channel. RDRAM
memory chips work in parallel to achieve a data rate of 800 MHz, or
1,600 MBps. Since they operate at such high speeds, they generate much
more heat than other types of chips. To help dissipate the excess heat
Rambus chips are fitted with a heat spreader, which looks like a long
thin wafer. Just like there are smaller versions of DIMMs, there are
also SO-RIMMs, designed for notebook computers.
is quite a useful piece of equipment, which allows the user to store
important information separate from the main internal
which could become compromised by online or offline activities. Sensitive
documents, large music files, DVD images, movies, disk images, and even a backup
of the contents of your main internal
can all be kept securely and safely on an
When you are online, usually recommended to leave the
Solide-state drive (SSD) is a data storage device which
uses a semiconductors without moving parts. This type of memory devices
are silent (noiseless) and less fragile than traditional hard disk
drivers. An SSD using SRAM or DRAM is often
called a RAM-drive.
Video and Sound cards:
The video card and its performance level are tied tightly to the performance of the other
components in the computer system. A PC with a top caliber processor will have faster
video performance than one with a slower CPU, all else being equal.
The type of motherboard (and a chipset), the amount and type of
memory, the size of system cache all also have an effect, as does the system bus.
The degree to which video performance is tied to the processor performance
depends on the application. The same is true for sound cards.
It is best to not change the Video and Sound cards, recommended
Power supply unit
(PSU). Manufactures offer a variety of computer
power supplies for all computing needs. Power sources range
from AC and DC adapters, power inverters, and many more options, helping
customers not only work in office, but also get out of the
office and into the world. Usually Power
supplies converts 110-115 or 220-230 volt alternating current (AC)
into a steady low-voltage direct current (DC) usable by the computer.
AC inputs include input voltage and input frequency. Choices for
input voltage include 115 VAC and 230 VAC. Input frequencies for
computer power supplies can be 50 Hz, 60 Hz, or 400 Hz. Common choices
for DC output voltage include +/- 3.3 V, +/- 5 V, +/- 12 V, +/- 15 V, +/- 24 V,
and +/- 48 V.
Power supplies generate a large amount of heat in
the process of converting the high voltage current into the lower voltage
currents. This is reason why active cooling fans have always been placed
inside of computer power supplies. Many of the newer power supplies will often
have 2 fans, one to pull air into the unit and one to expel the hot air out of
Rechargeable battery for portable computer. A portable computer usually is powered by mains
electricity via an AC adapter, and can be used away from an outlet using a
rechargeable battery. A battery in new condition typically stores enough
energy to run the portable computer for three , five and more hours,
depending on the computer usage, configuration and power management settings. When for example, a laptop is plugged into
the jack, the battery charges, whether or not the computer is running. A
battery life of last Toshiba netbook is more than 8 hours.
Most laptops use batteries that can last for 3-5 years, or about 1000 charges.
(A premium laptop's battery might last longer.) Every time you charge your
battery, the total capacity of the battery is diminished. Fox example, if
originally it may have had a run time of 3.5 hours, but after a year it will
run out of juice at 3 hours, even on a full charge. If your battery capacity has
diminished, there are a few things you can do about it. First, you have to
correctly gauge how much capacity has been lost. There are free downloads to do
this job, like
Bar (for Windows PCs) or
Coconut Battery (for
Macs). These will compare your battery's current maximum capacity to how
long it lasted when it was new.
cases: The case holds the
motherboard, drives, cooling systems, power supply system, and so on. It also
protects the system from the outside world. Case can have the different forms:
desktop, tower, mid tower, there are on the market the computers with
everything inside of keyboard (CYBERNET, Inc.) , or flat panel (IBM) and other
unusual forms. Sometimes companies create "form-factor" cases (or type of
physical arrangement of a computer hardware object). For example, IBM used
many form-factors: desktop, integrated Flat panel PC, mini desktop, small form
factor, and tower. When buying a computer , make sure that case is expandable.
There is nothing worse than needing a new hard drive and not having any room for
it. The case is also the item that helps to connect together all computer
equipment. It means, that it must have all necessary jacks and ports. Also,
make sure the case looks good. An ugly case can be a real reason to swap a