CIO-Information Technology

A buffer is basically an area of memory that a hardware device or software program uses when it needs a constant, uninterrupted flow of information. For example, if you ever listened to any kind of streamlining audio, the program you use probably "buffers" the signal a little before the music starts to play.

Here's how it works... Your audio program "collects" a few seconds of audio, then starts playing them. If there is a split second interruption, you don't notice it since the audio you are listening to is already a couple seconds old. Since you are not listening to an audio at the same instant it comes in, it gives the program a few seconds to compensate for any slight interruptions (and there are lots of those). It doesn't always work if the connection isn't good, but it does help.

A name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URL http://www.pcwebopedia.com/index.html, the domain name is pcwebopedia.com.

Every domain name has a suffix that indicates which top level domain (TLD) it belongs to. There are only a limited number of such domains. For example:

• gov - Government agencies
• edu - Educational institutions
• org - Organizations (nonprofit)
• mil - Military
• com - commercial business
• net - Network organizations
• ca - Canada
• th - Thailand

Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses.

There are a variety types of links used in technology:

(1) In programming, the term link refers to execution of a linker (is a program that combines object modules to form an executable program).

(2) To paste a copy of an object into a document in such a way that it retains its connection with the original object. Updates to the original object can be reflected in the duplicate by updating the link.

(3) In spreadsheet programs, linking refers to the ability of a worksheet to take its data for particular cells from another worksheet. Two or more files are thus linked by common cells.

(4) In communications, a link is a line or channel over which data is transmitted.

(5) In data management systems, a link is a pointer to another record. You can connect one or more records by inserting links into them.

(6) In some operating systems (UNIX, for example), a link is a pointer to a file. Links make it possible to reference a file by several different names and to access a file without specifying a full path.

(7) In hypertext systems, such as the World Wide Web, a link is a reference to another document. Such links are sometimes called hot links because they take you to other document when you click on them.

(8) To connect two or more computers together through a modem, cable, or network.

• RAM (random-access memory): This is the same as main memory. When used by itself, the term RAM refers to read and write memory; that is, you can both write data into RAM and read data from RAM. This is in contrast to ROM, which permits you only to read data. Most RAM is volatile, which means that it requires a steady flow of electricity to maintain its contents. As soon as the power is turned off, whatever data was in RAM is lost.
• ROM (read-only memory): Computers almost always contain a small amount of read-only memory that holds instructions for starting up the computer. Unlike RAM, ROM cannot be written to.
• PROM (programmable read-only memory): A PROM is a memory chip on which you can store a program. But once the PROM has been used, you cannot wipe it clean and use it to store something else. Like ROMs, PROMs are non-volatile.
• EPROM (erasable programmable read-only memory): An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light.
• EEPROM (electrically erasable programmable read-only memory): An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge.

A motherboard is the physical arrangement in a computer that contains the computer's basic circuitry and components. On the typical motherboard, the circuitry is imprinted or affixed to the surface of a firm planar surface and usually manufactured in a single step. Tthe computer components included in the motherboard are:

• Microprocessor
• (Optionally) Coprocessors
• Memory
• Basic Input/Output System (BIOS)
• Expansion Slot
• Interconnecting Circuitry

Additional components can be added to a motherboard through its expansion slot. The electronic interface between the motherboard and the smaller boards or cards in the expansion slots is called the bus.

A group of two or more computer systems linked together. There are many types of computer networks, including:

• local-area networks (LANs) : The computers are geographically close together (that is, in the same building).
• wide-area networks (WANs) : The computers are farther apart and are connected by telephone lines or radio waves.
• campus-area networks (CANs) : The computers are within a limited geographic area, such as a campus or military base.
• metropolitan-area networks MANs) : A data network designed for a town or city.
• home-area networks (HANs) : A network contained within a user's home that connects a person's digital devices.

Refers to the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bit-mapped graphic images. In the case of dot-matrix and laser printers, the resolution indicates the number of dots per inch. For example, a 300-dpi (dots per inch) printer is one that is capable of printing 300 distinct dots in a line 1 inch long. This means it can print 90,000 dots per square inch.

For graphic monitors, the screen resolution signifies the number of dots (pixels) on the entire screen. For example, a 640-by-480 pixel screen is capable of displaying 640 distinct dots on each of 480 lines, or about 300,000 pixels. This translates into different dpi measurements depending on the size of the screen. For example, a 15-inch VGA monitor (640x480) displays about 50 dots per inch.

Printers, monitors, scanners, and other I/O devices are often classified as high resolution, medium resolution, or low resolution . The actual resolution ranges for each of these grades is constantly shifting as the technology improves.

The global address of documents and other resources on the World Wide Web.

The first part of the address indicates what protocol to use, and the second part specifies the IP Address or the domain name where the resource is located.

For example, the two URLs below point to two different files at the domain pcwebopedia.com. The first specifies an executable file that should be fetched using the FTP protocol; the second specifies a Web page that should be fetched using the HTTP protocol:

• ftp://www.pcwebopedia.com/stuff.exe
• http://www.pcwebopedia.com/index.html

Computer program used to infect a computer. After the virus code is written, it is buried within an existing program. Once that program is executed, the virus code is activated and attaches copies of itself to other programs in the system. Infected programs copy the virus to other programs.

The effect of the virus may be a simple prank that pops up a message on screen out of the blue, or it may destroy programs and data right away or on a certain date. It can lay dormant and do its damage once a year. For example, the Michelangelo virus contaminates the machine on Michelangelo's birthday.

Viruses Must Be Run to Do Damage
A virus is not inserted into data. It is a self-contained program or code that attaches itself to an existing application in a manner that causes it to be executed when the application is run. Macro viruses, although hidden within documents (data), are similar. It is in the execution of the macro that the damage is done.

E-Mail Attachments Are Suspect
Files attached to e-mail messages are a common way of infecting a computer when the recipient is not aware of file types that are potentially harmful. For example, files with extensions such as .EXE, .BAT and .COM can perform any operation within the computer and should never be clicked unless the user is expecting the attachment.

Viruses Are Relatively Recent
The term virus was coined in the early 1980s, supposedly after a graduate student presented the concept of a program that could "infect" other programs. Since then, more than 80,000 viruses have been defined. However, 99% of the infections are from only a few hundred variants found. Since 1993, the WildList Organization has been keeping track of virus attacks around the world.

Be Careful
If you use the Internet for any purpose, be sure you have an antivirus program running at all times.