The A+ Certification & PC Repair Handbook (Charles River Media Networking/Security)

A measurement of computer system data storage space. One gigabyte is equal to 1024MB, or approximately 1 million kilobytes.

A worldwide satellite navigational system that was designed originally for the U.S. military under the name NAVSTAR (Navigation System with Timing and Ranging). Even though its utility has crossed over into the civilian sector, it is still operated by the U.S. Department of Defense. Twenty-four GPS satellites continuously transmit digital radio signals of data, such as the satellite’s location and the exact time, to their corresponding earth-bound receivers. By knowing how far away a satellite is from its receiver and its location on an imaginary sphere, GPS can be used to calculate longitude, latitude, and even altitude.

See video card.

See video card.

The Windows interface that makes use of graphical elements for controls, using such objects as buttons to click and the procedure of clicking and dragging. Contrast to text-based interface.

Allows an operating system to interact with hardware devices at a more general or abstract level.

When a program or OS process gets stuck at a certain point and doesn’t continue.

A device that stores data on permanently enclosed magnetic disks. The vast majority of computers have at least one hard drive. Data stored on a hard drive remains after the power is disconnected. The OS (such as Windows), along with programs and data, are almost always stored on a hard drive. Synonyms: hard disk drive, HDD.

A document that contains a list of all hardware compatible with a specific OS.

A small metal radiator used to allow heat to dissipate from heat-producing electrical devices, especially processors. Fans are often mounted on heat sinks to facilitate dissipation of heat.

See hexadecimal number.

A base-16 number. With decimal numbers, after 9 comes 0, and the 1 is carried over into the next column. Hex numbers include the following digits: 0123456789ABCDEF. After F comes 0, and the 1 is carried over into the next column. For example, F hex equals 15 in decimal, and 10 hex equals 16 in decimal. The purpose of hex numbers is to shorten what would otherwise be very long decimal numbers when referring to random access memory addresses and input/output addresses on a computer.

Saving the desktop as it is with all open programs and applets the way they are to the hard drive, and then shutting off the power. When power is resumed, the desktop should appear exactly as it was when it was hibernated. Synonym: suspend.

The memory location consisting of the first 64K of the extended memory area. The HMA is controlled by the software driver HIMEM.SYS.

Capable of being connected or disconnected from the computer or peripheral without risk of damage. Synonym: Hot-swappable.

A programming language that is used to create pages or hypertext documents on the World Wide Web. HTML is a scripting language that uses tags to define the way Web pages are displayed. E-mail messages using anything more than plain text use HTML.

A fast Internet application protocol used for transferring data.

A now obsolete form of ‘differential’ signaling that is commonly used for long runs in noisy areas. LVD (Low-Voltage Differential) is the new technology replacing HVD.

A type of connector that displaces the insulation on a cable, allowing an electrical contact between the terminal and conductor. Insulation displacement occurs as the cable is pressed into a terminal slot smaller than the conductor diameter. Insulation displacement technology has become a highly effective alternative to stripping and soldering wire in thousands of applications, with its greatest benefit being placement spread.

A specification for hard disk and CD-ROM drive interfaces whose drive controllers are integrated onto the drive itself. IDE provides support for up to two drives per system, whereas EIDE supports up to four drives per system. Today, the more common reference used for this technology is ATA.

The world’s leading international standards organization whose primary purposes are the development of information technology standards and the welfare of its members.

A standard for parallel cables. IEEE 1284-certified cables are more likely than noncertified cables to work reliably.

See FireWire.

To start a hardware device.

A term used to describe devices and programs that transfer information into and out of a computer system. Input devices can include keyboards, mice, and touch screens. Output devices can include printers, monitors, and plotters.

A location of a hardware device communication channel in a motherboard. Expressed in a hex number. I/O address ranges must be different for each hardware device installed in a computer.

A TCP/IP protocol used primarily to allow computers to be connected in a local area network or to the Internet.

A Novell networking protocol used primarily with Novell Netware.

A channel from a hardware device to the processor used to get the processor to respond to the device’s request for attention. There are a limited number of IRQs on a computer, and two devices cannot use the same IRQ at the same time. If two devices attempt to use the same IRQ to communicate with the CPU, an IRQ conflict will most likely occur.

An industry standard that describes the expansion bus architecture for the IBM AT and XT PCs. ISA expansion slots can still be found in some systems today, although they are steadily being replaced by PCI and AGP technology.

A digital communications standard that allows data and voice to be used on the same phone line connection. ISDN provides support for up to 128Kbps transfer rates and is intended to replace traditional analog technology.

A company whose primary business is to provide access to the Internet for other companies and individuals.