AGP
Accelerated Graphics Port is a type of
expansion card slot on the mother board that
is optimized to work with high performance
video cards. They enable better viewing of
3D graphics and full motion video on your
display.
BIOS
Basic Input Output System is code used when
a PC first starts up. It contains
configuration information about all the
Input and Output devices in the PC so that
the processor chip knows how to connect to
and work with them.
BIT
This is binary digit and is the smallest
piece of information a computer uses. A bit
is always in one of two states, either 0 or
1, except for the tiny instant of time
required to switch from one state to the
other.
BYTE
A byte is eight bits. The data and
instructions (code) that a CPU uses are
coded into bytes. For example capital letter
'A' in ASCII (PC) code is byte 0100 0001. A
lower case 'a' is byte 0110 0001.
BROWSER
Software on a computer used to request and
display web pages from a Server.
CABLE MODEM
A type of modem that provides very high
speed access to the Internet over the same
cable that your cable TV service uses. Rates
are asymmetric. This means that downloads
are much faster than uploads. Typical
download rates are 2 to 3 Mbps and uploads
are in the 500Kbs range. This is blazing
speed compared to a 56Kbps dial-up modem.
CACHE
Cache is a small fast SRAM type of memory.
It prevents CPU slowdown, which happens when
the CPU has to wait on slower devices like
RAM memory and the hard drive. There are two
levels of cache.
Level 1 or L1 cache is a small fast memory
located on the same chip as the CPU. When
files are first requested by the CPU they
are read into the CPU from the hard drive
and written into the L1 cache at the same
time. When the CPU needs data again it
checks the L1 cache and if it finds it there
it gets it instantly. If not, it looks
successively in the L2 cache, RAM and
finally the hard drive, each of which is a
little slower in delivering the data the CPU
has requested.
If the CPU finds the data it wants in a
cache it's called a 'hit' and that's good.
If it doesn't it's called a 'miss' which
makes the CPU wait a little longer to get
the data or instruction it needs from one of
the other slower devices.
This little bit of time saved by cache hits
may not seem significant, but keep in mind
that millions of accesses can be performed
in a second. Every cache hit shaves time off
the data access. Every cache miss adds time
to the access. Cache misses lower
performance and cache hits raise it!
Because level 2 or L2 cache is located in
chips on the motherboard or on the board
that holds the CPU it takes a little longer
to access than the L1 cache.
L2 cache is becoming more important as it
grows in size and performance. The L1 cache
is very small because it is on the same chip
as the large CPU. Due to it's small size,
chances are high that the CPU won't find the
data it needs there. An L1 cache miss causes
the CPU to look in the L2 cache for the
data.
The long and short of all this - If the data
the CPU needs is not found in the L1 cache
or L2 cache, the CPU must to wait to get it
from the RAM memory. And if it isn't in RAM,
then the CPU goes on vacation for a number
of milliseconds, which is a long time in the
CPU world, while the data is retrieved from
the hard drive.
CDD
Compact Disk Drive is a storage device that
uses optics to read data from compact disks.
CDDs that can read as well as write are very
popular now.
CPU
The Central Processing Unit is a special
chip that controls what happens in a PC. It
fetches instructions and does high speed
computations on data. It is somewhat like
our brain in that it controls everything we
do.
DIMM
Dual Inline Memory Module is a small printed
circuit board that contains DRAM memory
chips. When we say a PC has 256 MBytes of
memory we are talking about the total
capacity of all the DIMM modules installed
in it.
Modern motherboard provide two to four
sockets that accept DIMMs.
DOMAIN NAME
A unique name, formed with letters and
numbers, that points to the actual numerical
Internet address which locates a particular
computer connected to the Internet. For
instance, The Yahoo domain name points to
Internet address 66.218.71.198.
So when you enter www.yahoo.com in your
browser and click go, a special server
called a domain name server intercepts and
directs your request to the server located
at address 66.218.71.198.
DRAM
Dynamic Random Access Memory is type of
memory that must constantly be refreshed to
retain it contents. It is used as the main
memory in a PC and is packaged in DIMMs
which plug into the motherboard.
DSL Modem
DSL stands Digital Subscriber Line. The DSL
modem is a fairly new device, which allows
high speed data to move between your PC and
the telephone company on the same line that
you use for your telephone calls. Yes. you
can use your PC and talk over this line at
the same time without interference!
How? Picture of a double-decker bridge with
two levels. The traffic on the two levels
does not interfere with each other even
though it is the same bridge, right? Think
of your phone call using the lower level and
your PC using the upper level. Instead of
being separated by different levels in
space, the separation is done by your PC and
voice each using a different carrier
frequency, just like two different radio
stations.
FAT16
FAT is the abbreviation for File Allocation
Table. It is a table where the system keeps
basic information for each file on your hard
drive. The 16 indicates the number of bits
used to address the hard drive. The largest
partition FAT16 can access is 2MB. When used
on a hard drive that is bigger than 2MB the
drive space will be divided into a number of
partitions.
For example a 10MB drive would be divided
into five partitions of 2MB each. If the
drive were the only one in the system the
partitions would be called C:, D:, E:, F:,
and G:.
FAT32
FAT is the abbreviation for File Allocation
Table. It is a table where the system keeps
basic information for each file on your hard
drive. The 32 indicates the number of bits
used to address the hard drive. The largest
partition FAT32 can access is 2 Terabytes
(two trillion bytes)! So far there are no
hard drives I know of that begin to approach
this size. Windows 98 was the first of the
Windows OS to support this file structure.
FDD
Floppy Disk Drive is a device which provides
a way for the PC to read and write floppy
disks, which are a type of removable storage
media. Floppy disks (3 1/2 inch) have a
capacity of 1.44 Mbytes. When PCs first came
out, floppy disks were 5 1/4 inch and held
720 Kbytes.
FIREWIRE
Firewire also known as IEEE 1394 or iLink is
a very fast serial bus that runs at 400
Mbps. It competes directly against USB 2.0.
Transmit and Receive data are carried on two
separately-shielded twisted pair
transmission lines. There are two other,
rarely used, wires that provide power to
remote devices.
Many newer computers have Firewire ports
that are used to connect them to very fast
external devices.
FTP
File Transfer Protocol is the method used by
computers to send and receive files over the
Internet.
HTML
Hyper Text Markup Language is the coding
that is used to format web pages on Servers
so that Browsers can display them.
HTTP
Hyper Text Transport Protocol is used by
browsers and servers to facilitate the
transport of web pages across the Internet.
HDD
Hard Disk Drive is a device that provides a
large fixed typically (non removable)
storage area. Some units today easily
removable from the front of the PC. The
capacity of HDDs has continued to increase.
40Gbyte drives are readily available and
inexpensive. The HDDs used in the first PC
had only 10Mbytes of storage.
IDE
Integrated Drive Electronics refers to the
electronic control section of a Hard or
Floppy Drive. This control section
coordinates the electromechanical operation
of the drive so that data can be written to
and read from the spinning disk inside it.
The motherboard connects to Drives over an
IDE ribbon cable.
I/O
This means Input/Output. Input is data or
signals that are fed into a device. Output
is data or signals that a device drives to
the outside. Some devices can do both,
others are only one or the other.
ISA
Industry Standard Architecture refers to a
type of expansion slot on the motherboard.
It is the oldest of all expansion type slots
and first appeared in the IBM PC XT.
Thousands of expansion or add-on cards as
they are also called, have been designed to
plug into the ISA slot. The use of expansion
cards vastly extends the function and
capability of the PC.
MEMORY NON-VOLATILE
Memory is a device that retains information
electronically. When power is removed the
information is retained.
MEMORY VOLATILE
Memory is a device that retains information
electronically. When power is removed the
information is lost. The DRAM memory used in
a PC is the volatile type.
OS
Operating Systems are the basic foundation
or platform programs that allow you to load
and run other programs on a PC. Windows 95
is an example of an Operating System.
PARALLEL PORT
The parallel port is a standard port on a PC
and moves data out of the PC. One byte
(eight bits in parallel) are sent out on 8
pins for each data transfer. Historically
this port is connected to your printer. It
also known as a 'Centronics' port, named
after the manufacturer of the 38- pin
connector first used on the parallel port.
PCI
Peripheral Component Interconnect refers to
a type of expansion slot found on PC
motherboards. It is a newer type of
expansion slot than ISA, and many types of
Add-On cards have been designed to use it.
RANDOM ACCESS
This refers to an access method. It means
that any random location in a storage or
memory device can be immediately accessed,
with out going serially to get there. It's
like a cassette where your at the beginning
and have to wind through everything on the
tape to get to the last song! Compact Disks
and PC Main memory are random access
devices.
SERIAL ACCESS
This access method is found in audio or
video cassettes. It means you can not access
any location you choose to instantly. You
might have to rewind or fast forward through
lots of information you are not interested
in to get to where you want to go.
SERIAL PORT
The serial port is standard port on a PC and
can move data in and out of the PC. The
serial port moves one bit on each data
transfer. Many different types of devices
connect to a PC through it.
SERVER
Software on a computer that serves web pages
in response to requests from a Browser.
SIMM
Single Inline Memory Module is a small
printed circuit board that contains DRAM
memory. This is an older board style that
was used in PCs before DIMMs were developed.
SRAM
Static Random Access Memory is type of
memory that retains data without being
refreshed. It is used in the cache memories
of the PC.
TROJAN HORSE
Trojan horses are dangerous programs that
appear like they might perform some useful
task, or provide entertainment. This false
appearance encourages people to run them.
When they are run, they can damage files or
place a virus on your computer.
Unlike a virus a Trojan horse does not
replicate and spread. Since it isn't a virus
it can't be repaired and must be erased from
your computer.
USB
Universal Serial Bus is a high speed serial
bus found on all newer PCs. Eventually it
will obsolete the serial and parallel ports
still found on most PCs.
USB specifies three data rates. Every USB
port may not support the highest rate. If
you buy a device with a USB port, make sure
out find out which rates it does support.
Low speed - 1.5Mb/s
Full Speed - 12Mb/s
High Speed - 480 Mb/s
VIDEO ADAPTER
The video adapter is circuit board found in
the PC or monitor that controls how data is
converted and sent to the monitor for
viewing.
Most displays and video adapters adhere to
the Video Graphics Array (VGA) standard,
which describes how data - the red, green,
blue data streams - are passed from the
computer to the display.
In addition, it defines the frame refresh
rates in hertz and the number and width of
horizontal lines, which in turn identifies
the screen resolution in pixels.
Here are some of the video standards that
have been used:
CGA is 320 x 200 - developed in 1981 by
IBM, no longer in use.
EGA is 640 x 350 - developed in 1984 by IBM,
no longer in use.
VGA is 640 x 480 - developed in 1987 by IBM
and still in use.
Super VGA is 800 x 600.
Extended Graphics Adapter, XGA is 1024 x
768.
Super XGA is 1280 x 1024.
Ultra XGA is 1600 x 1200.
VIRUS
It is a program designed to change the way
your computer operates without your
permission or knowledge. When a virus
attaches itself to another file, it infects
it. Any time you activate an infected file
it can damage files, cause erratic system
behavior, or display messages. Some system
viruses are programmed specifically to
corrupt programs, delete files, or erase
your disk.
Viruses are inactive until you run an
infected program, start your computer from a
disk with infected system files, or open an
infected file. Once a virus is active in
memory it can infect any other programs,
local or network, that you run.
Files infected with a virus can be
inoculated (the virus is removed from the
program).
WORM
Worms are a close cousin to viruses and
Trojan Horses. Unlike a virus they don't
infect other programs. They do however make
many copies of themselves in memory, which
effectively consumes all your memory. This
leaves no memory to run you regular
programs. Your PC may behave very
erratically, or just grind to a halt!
Some worms get into your e-mail list and
e-mail themselves to everyone on your e-mail
list without you knowledge. When each
unsuspecting recipient opens such an e-mail,
it broadcasts itself to everyone on their
e-mail list. This is how worms rapidly
travel throughout the Internet! Worms can
not be repaired since they are not viruses.
They must be erased from your computer, the
sooner the better! |
