Glossary of Computer Terms

AGP

Accelerated Graphics Port is a type of expansion card slot on the mother boardthat is optimized to work with high performance video cards. They enable betterviewing 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 containsconfiguration information about all the Input and Output devices in the PC sothat the processor chip knows how to connect to and work with them.

BIT

This is binary digit and is the smallest piece of information acomputer uses. A bit is always in one of two states, either 0 or 1, except forthe 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 arecoded into bytes. For example capital letter 'A' in ASCII (PC) code is byte0100 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 thesame cable that your cable TV service uses. Rates are asymmetric. This meansthat downloads are much faster than uploads. Typical download rates are 2 to 3Mbps and uploads are in the 500Kbs range. This is blazing speed compared to a56Kbps dial-up modem.

CACHE

Cache is a small fast SRAM type of memory. It prevents CPU slowdown, whichhappens when the CPU has to wait on slower devices like RAM memory and the harddrive. There are two levels of cache.

Level 1 or L1 cache is a small fast memory located on the samechip as the CPU. When files are first requested by the CPU they are read intothe 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 thereit gets it instantly. If not, it looks successively in the L2 cache, RAM andfinally the hard drive, each of which is a little slower in delivering the datathe CPU has requested.

If the CPU finds the data it wants in a cache it's called a 'hit' and that'sgood. If it doesn't it's called a 'miss' which makes the CPU wait a littlelonger 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 keepin mind that millions of accesses can be performed in a second. Every cache hitshaves 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 motherboardor on the board that holds the CPU it takes a little longer to access than theL1 cache.

L2 cache is becoming more important as it grows in size and performance. The L1cache is very small because it is on the same chip as the large CPU. Due toit's small size, chances are high that the CPU won't find the data it needsthere. 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 theL1 cache or L2 cache, the CPU must to wait to get it from the RAM memory. Andif 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 thehard drive.

CDD

Compact Disk Drive is a storage device that uses optics to read data fromcompact 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 aPC. It fetches instructions and does high speed computations on data. It issomewhat like our brain in that it controls everything we do.

DIMM

Dual Inline Memory Module is a small printed circuit board that contains DRAMmemory chips. When we say a PC has 256 MBytes of memory we are talking aboutthe 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 actualnumerical Internet address which locates a particular computer connected to theInternet. For instance, The Yahoo domain name points to Internet address66.218.71.198.

So when you enter www.yahoo.com in your browser and click go, a special servercalled a domain name server intercepts and directs your request to the serverlocated at address 66.218.71.198.

DRAM

Dynamic Random Access Memory is type of memory that must constantly berefreshed to retain it contents. It is used as the main memory in a PC and ispackaged in DIMMs which plug into the motherboard.

DSL Modem

DSL stands Digital Subscriber Line. The DSL modem is a fairly new device, whichallows high speed data to move between your PC and the telephone company on thesame line that you use for your telephone calls. Yes. you can use your PC andtalk over this line at the same time without interference!

How? Picture of a double-decker bridge with two levels. The traffic on the twolevels 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 theupper level. Instead of being separated by different levels in space, theseparation is done by your PC and voice each using a different carrierfrequency, just like two different radio stations.

FAT16

FAT is the abbreviation for File Allocation Table. It is a table where thesystem keeps basic information for each file on your hard drive. The 16indicates the number of bits used to address the hard drive. The largestpartition FAT16 can access is 2MB. When used on a hard drive that is biggerthan 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. Ifthe 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 thesystem keeps basic information for each file on your hard drive. The 32indicates the number of bits used to address the hard drive. The largestpartition FAT32 can access is 2 Terabytes (two trillion bytes)! So far thereare no hard drives I know of that begin to approach this size. Windows 98 wasthe 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 writefloppy disks, which are a type of removable storage media. Floppy disks (3 1/2inch) have a capacity of 1.44 Mbytes. When PCs first came out, floppy diskswere 5 1/4 inch and held 720 Kbytes.

FIREWIRE

Firewire also known as IEEE 1394 or iLink is a very fast serial bus that runsat 400 Mbps. It competes directly against USB 2.0. Transmit and Receive dataare carried on two separately-shielded twisted pair transmission lines. Thereare two other, rarely used, wires that provide power to remote devices.

Many newer computers have Firewire ports that are used to connect them to veryfast external devices.

FTP

File Transfer Protocol is the method used by computers to send and receivefiles over the Internet.

HTML

Hyper Text Markup Language is the coding that is used to format web pages onServers so that Browsers can display them.

HTTP

Hyper Text Transport Protocol is used by browsers and servers to facilitate thetransport of web pages across the Internet.

HDD

Hard Disk Drive is a device that provides a large fixed typically (nonremovable) storage area. Some units today easily removable from the front ofthe PC. The capacity of HDDs has continued to increase. 40Gbyte drives arereadily available and inexpensive. The HDDs used in the first PC had only10Mbytes of storage.

IDE

Integrated Drive Electronics refers to the electronic control section of a Hardor Floppy Drive. This control section coordinates the electromechanicaloperation of the drive so that data can be written to and read from thespinning disk inside it. The motherboard connects to Drives over an IDE ribboncable.

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 cando 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 PCXT. Thousands of expansion or add-on cards as they are also called, have beendesigned to plug into the ISA slot. The use of expansion cards vastly extendsthe function and capability of the PC.

MEMORY NON-VOLATILE

Memory is a device that retains information electronically. When power isremoved the information is retained.

MEMORY VOLATILE

Memory is a device that retains information electronically. When power isremoved the information is lost. The DRAM memory used in a PC is the volatiletype.

OS

Operating Systems are the basic foundation or platform programs that allow youto load and run other programs on a PC. Windows 95 is an example of anOperating System.

PARALLEL PORT

The parallel port is a standard port on a PC and moves data out ofthe PC. One byte (eight bits in parallel) are sent out on 8 pins for each datatransfer. Historically this port is connected to your printer. It also known asa 'Centronics' port, named after the manufacturer of the 38- pin connectorfirst used on the parallel port.

PCI

Peripheral Component Interconnect refers to a type of expansion slot found onPC motherboards. It is a newer type of expansion slot than ISA, and many typesof 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 storageor memory device can be immediately accessed, with out going serially to getthere. It's like a cassette where your at the beginning and have to windthrough everything on the tape to get to the last song! Compact Disks and PCMain memory are random access devices.

SERIAL ACCESS

This access method is found in audio or video cassettes. It means you can notaccess any location you choose to instantly. You might have to rewind or fastforward through lots of information you are not interested in to get to whereyou want to go.

SERIAL PORT

The serial port is standard port on a PC and can move data in and out of thePC. The serial port moves one bit on each data transfer. Many different typesof devices connect to a PC through it.

SERVER

Software on a computer that serves web pages in response to requests from aBrowser.

SIMM

Single Inline Memory Module is a small printed circuit board that contains DRAMmemory. This is an older board style that was used in PCs before DIMMs weredeveloped.

SRAM

Static Random Access Memory is type of memory that retains data without beingrefreshed. It is used in the cache memories of the PC.

TROJAN HORSE

Trojan horses are dangerous programs that appear like they might perform someuseful task, or provide entertainment. This false appearance encourages peopleto run them. When they are run, they can damage files or place a virus on yourcomputer.

Unlike a virus a Trojan horse does not replicate and spread. Since it isn't avirus 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 mostPCs.

USB specifies three data rates. Every USB port may not support the highestrate. If you buy a device with a USB port, make sure out find out which ratesit 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 howdata 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 - arepassed from the computer to the display.

In addition, it defines the frame refresh rates in hertz and the number andwidth of horizontal lines, which in turn identifies the screen resolution inpixels.

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 yourpermission or knowledge. When a virus attaches itself to another file, itinfects it. Any time you activate an infected file it can damage files, causeerratic system behavior, or display messages. Some system viruses areprogrammed specifically to corrupt programs, delete files, or erase your disk.

Viruses are inactive until you run an infected program, start your computerfrom a disk with infected system files, or open an infected file. Once a virus isactive in memory it can infect any other programs, local or network, that yourun.

Files infected with a virus can be inoculated (the virus is removed from theprogram).

WORM

Worms are a close cousin to viruses and Trojan Horses. Unlike a virus theydon't infect other programs. They do however make many copies of themselves inmemory, which effectively consumes all your memory. This leaves no memory torun you regular programs. Your PC may behave very erratically, or just grind toa halt!

Some worms get into your e-mail list and e-mail themselves to everyone on youre-mail list without you knowledge. When each unsuspecting recipient opens suchan e-mail, it broadcasts itself to everyone on their e-mail list. This is howworms rapidly travel throughout the Internet! Worms can not be repaired sincethey are not viruses. They must be erased from your computer, the sooner thebetter!

Wireless Mouse and Keyboard

Wireless Mouse

The wireless mouse has scurried onto the scene in recent years. It's primarybenefit is not having to drag around the wire that connects it to your PC.Instead it communicates with Infrared light (IR) or radio waves (RF) to a podthat is connected to your PC's PS/2 or USB port.

Infrared Type

The first wireless mouse used Infrared light to communicate with the pod. Thisis the same technology that is used in your TV remote controller, and as youknow the distance between controller and TV can be many feet apart. The mouseand pod have the same long distance range. The major drawback is when somethinggets between the controller and the TV, it doesn't work. The IR mouse has thesame drawback, it must have a direct line-of-sight to the pod or it doesn'twork. Some stores still offer them and they fairly inexpensive.

RF Type

The next type of wireless mouse to show up was the RF mouse. It uses the sametechnology as in your car remote lock controller. As with the car lockcontroller the mouse does not need line-of-sight to work, which means if youput a coffee cup in front of the pod connected to your PC, the RF wirelessmouse keeps communicating with the pod. The transmitter in the mouse can havedifferent power ratings which translate into different working distances fromthe pod. Most are rated at 3 feet, 6 feet or 30 feet. The 30 foot range isspecified for Bluetooth, which is an emerging RF specification for wirelesslyconnecting together many devices in a small area. For most PC users 3 or 6 feetis fine. These devices are about twice the cost of the IR type mouse.

In addition to the wireless communication between mouse and pod, just about allwireless mice use optical means to convert the back and forth, side-to-sidemouse movements you make with your mouse into the pointer movements you see onyour display. The older trackball mouse is heading for that big cheese in thesky! Click Here for more information.

Wireless Keyboard

They use the same IR or RF technology as the wireless mouse tocommunicate with a pod. You can often buy a wireless mouse and wirelesskeyboard set that communicates with a single pod that connects to your PC.

Which processor is right for you?

The central processor unit (CPU), often called just the'processor', is the heart of the PC. It controls everything that happens in thecomputer, but its overall performance is determined by a couple of factors. Thefirst is clock speed which is measured in Ghz (billions of clock cycles persecond). The second is the size of the L2 cache that the processor uses.

L2 cache is a special memory that the processor uses frequently. It is locatedless than an inch or so from the processor. It is a very fast memory and sharesdata with the processor on a private connection known as the back side bus.

Faster clock speeds and bigger L2 caches translate into higher performance. TheIntel Pentium class of processors are the most popular type found in PCs, andare offered in a couple of versions:

The Celeron is an entry level processor. It is really a Pentium 4 that runs ata slower clock speed and uses a smaller L2 cache. A smaller L2 cache guaranteesmore overall cache misses which results in lower performance.

A Pentium 4 runs at it's full rated speed and uses a large L2 cache.

AMD makes processors that directly compete with Intel, see below.

Recommendation:

The chief competitor for Intel is AMD (Advanced Micro Devices). They make theAthlon processor which competes with the Pentium 4 and the Duron which competeswith the Celeron.

If you want to surf the web, send and receive e-mails, create basic wordprocessor and spreadsheet documents, then a 1.7Ghz or higher Celeron or Duronwill work fine for you.

For those who want to run high performance applications that require seriousnumber crunching and fast graphics, then a Pentium 4 or Athlon processorrunning at or above 2Ghz is the way to go.

We've used AMD and Intel processors and both are excellent processors. Youcan't go wrong with either one.

What sound quality do you want from your PC?

As the PC has evolved from a plain computer to an entertainmentcenter, the sound quality it produces has become an important consideration.

Most PCs come equipped with motherboards that have integrated sound chips thatprovide connectors for speakers, a headphone and line-in. Having an integratedsound card means that a separate sound card is not required.

A set of speakers is also part of the standard PC package. They can be thestand-alone type or the type that are integrated into the sides of yourmonitor. They are usually of low to mid grade quality.

Recommendation:

For everyday use the standard set up described above is sufficient.

If you're an audiophile, a music producer or a game player who wants the latestsurround sound effects, then a Sound Blaster card from Creative Labs or aTurtle Beach card from SantaCruz is what you would install in your PC.

When combined with a good set of speakers your PC can create very high qualityaudio. Logitech, Creative Labs and Altec Lansing make speakers designed forPCs.

To add a full, rich bass sound get a three-speaker system that includes awoofer speaker along with the left and right stereo speakers. If you want touse your PC to watch movies then go with a five-speaker system that providesfull, home theater surround sound.

What ports does your PC have?

Ports are pathways that connect your PC to external devices, orperipherals as they are called. Up until recently they were always located atthe back of the PC. They are now often found on the front of it as well.

USB

USB (Universal Serial Bus) has become one of the most popular ports found on aPC. All new PCs have at least 2 USB ports. Printers, scanners, and many otherperipheral products have USB ports which makes it very easy to connect them toyour PC.

USB is very user friendly and supports what is called Plug'n'Play. This meansthat when you connect a device to your PC with USB, it is automaticallydetected and set up without your intervention. In some cases, you may have toinstall a device driver provided by the manufacturer on a CD or on their website.

USB is available in a couple of standards. USB 2.0 is the fastest at 480Mbps(million bits per second). The earlier USB 1.1 runs at 12Mbps.

Firewire

Firewire is another type of port found on newer PCs. It is also known as i.LINKor IEEE 1394 and is rated at 400Mbps which puts it in the same speed class asUSB 2.0.

When Firewire first came out, only USB 1.1 was available and many observersthought it would push USB out of the picture. With the advent of USB 2.0 andit's proliferation into so many peripheral devices, USB is here to stay.

Flash Card

Many new PCs provide ports for reading and writing flash cards. This allows youto access data directly from the flash card without having to connect yourdigital camera or PDA.

Recently I saw a new PC from HP that had a port with multiple slots forconnection to many flash card types: Compact Flash I/II, SmartMedia, MemoryStick/Pro, MultiMediaCard and Secure Digital.
If you use a PDA or digital camera this type of port comes in very handy.

Legacy ports

Most PCs still have parallel, serial or game ports. These ports are always puton the back of the newer PCs and will eventually be phased out.

Recommendation:

Buy peripheral products that use a USB port. Why? Every PC produced in the lastfew years has at least 2 USB ports on it. This makes it a given that mostdevices can connect to a PC and run right away. Most camcorders, however,connect to the PC through a Firewire port.

Make sure you know what USB standard your PC supports. It may only support theolder USB 1.1 type.

If you want to connect more than two USB devices to your PC, where would thethird one plug in? The solution is provided by a device called a USB Hub. Itplugs into one of the PC's USB ports and allows from 4 to 8 USB devices to pluginto it. The ability to quickly scale up and connect to multiple devicescombined with the fact that almost every peripheral has one makes USB the portof choice.

If you have devices that use flash cards, then a PC equipped with ports thatcan read and write them is quite useful. If the PC doesn't have this type ofport built in don't worry, you can connect an external flash card adapter toyour PC later on using - what else - a USB port!