(See related pages)
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| Central Processing Unit (CPU) | The unit of a computer system that includes the circuits that control the interpretation and execution of instructions. In many computer systems, the CPU includes the arithmetic-logic unit, the control unit, and the primary storage unit. |
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| Computer System | Computer hardware as a system of input, processing, output, storage, and control components. Thus, a computer system consists of input and output devices, primary and secondary storage devices, the central processing unit, the control unit within the CPU, and other peripheral devices. |
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| Computer Terminal | Any input/output device connected by telecommunications links to a computer. |
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| Direct Access | A method of storage in which each storage position has a unique address and can be individually accessed in approximately the same period without having to search through other storage positions. Same as Random Access. Contrast with Sequential Access. |
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| Graphical User Interface | A software interface that relies on icons, bars, buttons, boxes, and other images to initiate computer-based tasks for users. |
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| Information Appliances | Small Web-enabled microcomputer devices with specialized functions, such as handheld PDAs, TV set–top boxes, game consoles, cellular and PCS phones, wired telephone appliances, and other Web-enabled home appliances. |
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| Magnetic Disk | A flat, circular plate with a magnetic surface on which data can be stored by selective magnetization of portions of the curved surface. Floppy Disk: A small plastic disk coated with iron oxide that resembles a small phonograph record enclosed in a protective envelope. It is a widely used form of magnetic disk media that provides a direct access storage capability for microcomputer systems. RAID: Redundant array of independent disks. Magnetic disk units that house many interconnected microcomputer hard disk drives, thus providing large, fault-tolerant storage capacities. |
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| Magnetic Tape | A plastic tape with a magnetic surface on which data can be stored by selective magnetization of portions of the surface. |
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| Microcomputer | A very small computer, ranging in size from a “computer on a chip” to handheld, laptop, and desktop units, and servers. |
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| Minicomputer | A type of midrange computer. |
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| Network Computer | A low-cost networked microcomputer with no or minimal disk storage, which depends on Internet or intranet servers for its operating system and Web browser, Java-enabled application software, and data access and storage. |
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| Offline | Pertaining to equipment or devices not under control of the central processing unit. |
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| Online | Pertaining to equipment or devices under control of the central processing unit. |
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| Optical Disks | A secondary storage medium using CD (compact disk) and DVD (digital versatile disk) technologies to read tiny spots on plastic disks. The disks are currently capable of storing billions of characters of information. |
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| Pointing Devices | Devices that allow end users to issue commands or make choices by moving a cursor on the display screen. |
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| Processing speed | Millisecond: A thousandth of a second. Microsecond: A millionth of a second. Nanosecond: One billionth of a second. Picosecond: One trillionth of a second. |
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| Secondary Storage | Storage that supplements the primary storage of a computer. Synonymous with auxiliary storage. |
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| Semiconductor Memory | Microelectronic storage circuitry etched on tiny chips of silicon or other semiconducting material. The primary storage of most modern computers consists of microelectronic semiconductor storage chips for random-access memory (RAM) and read-only memory (ROM). Random-Access Memory (RAM): One of the basic types of semiconductor memory used for temporary storage of data or programs during processing. Each memory position can be directly sensed (read) or changed (written) in the same length of time, regardless of its location on the storage medium. Read-Only Memory (ROM): A basic type of semiconductor memory used for permanent storage. Can only be read, not “written,” that is, changed. Variations are Programmable Read-Only Memory (PROM) and Erasable Programmable Read-Only Memory (EPROM). |
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| Sequential Access | A sequential method of storing and retrieving data from a file. Contrast with Random Access and Direct Access. |
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| Speech Recognition | Direct conversion of spoken data into electronic form suitable for entry into a computer system. Also called voice data entry. |
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| Storage capacity | Bit: A contraction of "binary digit." It can have the value of either 0 or 1. Byte: A sequence of adjacent binary digits operated on as a unit and usually shorter than a computer word. In many computer systems, a byte is a grouping of eight bits that can represent one alphabetic or special character or that can be packed with two decimal digits. Megabyte: One million bytes. More accurately, 2 to the 20th power, or 1,048,576 in decimal notation. Gigabyte: One billion bytes. More accurately, 2 to the 30th power, or 1,073,741,824 in decimal notation. Terabyte: One trillion bytes. More accurately, 2 to the 40th power, or 1,009,511,627,776 in decimal notation. |