Glossary

Algorithm   According to Donald Knuth, “A finite set of rules, which gives a sequence of operations for solving a specific type of problem.”¹ Like a recipe to cook a dish, only every step is precisely defined so that a machine can carry the steps out. Implied is that these steps be completed in a finite amount of time.

ARPA   Advanced Research Projects Agency, established by the U.S. Defense Department in 1968. A research agency not affiliated with the specific services, which has been charged with advanced research not necessarily tied to a specific weapons system. The initial acronym was later changed to DARPA.

Artificial Intelligence (AI)   The classic definition is that of a computer that performs actions that, if done by a human being, would be considered intelligent. In practice, as computers become more powerful, actions such as playing a good game of chess are no longer considered AI, although they once were considered at the forefront of AI research. At the same time, despite decades of research and advances in technology, no computer has an ability to converse with a human being in a normal fashion on a variety of topics.

Binary   A representation of numbers or values where only two values are allowed. This can be, for example, 1 or 0 in arithmetic, yes or no in logic, on or off for an electrical switch, or the presence of absence of a current in a wire. Although less comfortable for humans who are accustomed to decimal (base 10) numbers, binary has overwhelming advantages from both an engineering and a theoretical standpoint.

Bit   A binary digit, either 1 or 0.

Boolean algebra   Like binary arithmetic, a system of logic that accepts only two values: true or false. The rules for manipulating these values are congruent to the rules for performing arithmetic in the binary system, with the numbers 1 and 0, with minor differences.

Byte   Eight bits, treated as a single unit. A sequence of eight bits is enough to encode the letters of the Roman alphabet in upper and lower case; the numerals, punctuation, and other symbols; and other special characters that may be used, for example, to control a printer. The typical measure of data storage capacity; for example, 100 Megabytes would be equal to 800 million bits of data.

Calculator   A mechanical or electronic device that evaluates the four functions of arithmetic: addition, subtraction, multiplication, and division.

Chatroom (or Chat room)   A virtual space found on computer networks in which a person types a message, which is read by all others who are logged into that space. They may in turn reply. The earliest chatrooms allowed no more than simple text. That was later augmented by voice and simple graphics, but basic text dominated. Chatrooms continue to be used, although social media services like Facebook have largely supplanted them.

Client-server   An arrangement of networked computers, in which “clients” (workstations or personal computers) receive data from large-capacity computers called “servers.” The data are typically in raw form, while the servers use their computing capacity to handle housekeeping, graphics, and other computations.

Compiler   A specialized computer program that accepts as input commands written in a form familiar to humans and produces as output instructions that a machine can execute, usually in the form of strings of binary numbers.

Computer   The definition of this term has changed over the years, but it generally refers to a machine, almost always using electronic components, that performs calculations, stores data, and carries out sequences of operations automatically. The modern definition assumes that the program that directs the computer’s operation is also stored internally in its memory, along with the data.

Control   In this context, the part of a computer that directs the other circuits to perform calculation, storage, input, and output as it decodes the instructions of a program.

Data   From the Latin word (plural; singular datum) for “things that are given.” Any information, in coded form, that a computer can process. Although derived from a plural word, data is often treated as a singular noun in English.

Electromechanical   A method of switching or manipulating electrical currents, in which the switching is done by metal contacts, which in turn are activated by electrical currents. These include so-called relays, which were once common in telephone switching, and the stepping switching of decimal wheels in a punched-card machine. Contrast with electronic, in which all the switching is done by electrons in either a vacuum or solid-state device.

Electronic   A method of switching that uses electrons moving at high speeds. No mechanical devices are used. Early electronic computers used vacuum tubes, later solid-state transistors and integrated circuits.

Graphical User Interface (GUI)   A method of interacting with a computer by clicking a mouse on symbolic information presented on a video screen. For most consumers, this has replaced the earlier method of directly typing in a command, such as “print” or “save.”

Integrated circuit   An electronic device in which all of the classic components of a circuit, such as resistors, transistors, capacitors, and their connecting wires, are combined on a single piece of material, usually silicon. Often called a microchip, or simply chip.

Internet   A term initially meant to designate a network of heterogeneous networks. The current meaning is of the worldwide network that uses the TCP/IP protocols, and conforms to the addressing of the Domain Name System, as administered by a governing body known as the Internet Corporation for Assigned Names and Numbers (ICANN).

LISP   List Processing, a computer language once favored by artificial intelligence researchers.

Memory   The part of a computer where data is stored. Computers have a hierarchy of memory devices, with a small memory, of lesser capacity, that stores and retrieves data at high speed, followed by slower but higher-capacity devices, such as spinning disks or magnetic tape drives. The anthropomorphic implications can be misleading, as computer memories operate on fundamentally different principles from human memory.

Microcode   Detailed computer programs that direct the detailed operations of a processor. Typically stored on read-only memory. See read-only memory.

Microprocessor   A device that contains most of the basic components of a general-purpose stored program computer on a single chip; typically used in conjunction with random-access memory and read-only memory chips. See random-access memory; read-only memory.

MOS   Metal-oxide semiconductor: a type of integrated circuit that lends itself to high densities and low power consumption.

Mouse   A device that allows a computer user to select items on a screen.

Operating System   A specialized program that manages the housekeeping chores of a computer, such as transferring data from its internal memory to a disk or to a terminal and interpreting clicks of a mouse or keystrokes.

Packet switching   A method of transmitting data over a computer network by breaking up a file into smaller sections, called packets, each packet also containing a header that gives information about the packet’s destination and contents. The technical basis for the Internet.

Program   A sequence of instructions executed by a computer to perform actions desired by its user. See also software.

Protocols   The conventions that govern the switching of packets. Similar to the addressing of a letter, which has conventions as to the placement of the destination and return address, the placement and amount of postage, and so on, regardless of the contents of the letter.

Random-access memory (RAM)   That portion of a computer’s memory that has the highest access speeds, and often at less capacity than a slower disk. The term is a misnomer, since it originally referred to a disk, in which the time it took to access a datum depended on the random placement of that information on the disk. It now refers to the internal memory, the access of which is nearly the same regardless of where it is placed.

Read-only memory (ROM)   That portion of a computer’s memory that stores data that can be read, but not changed by the user. Typically a read-only memory chip stores programming (see microcode) that tailors the microprocessor to execute specific functions.

Relay   A mechanical switch that is activated by an electromagnet. The term came from telegraphy, in which a telegraph signal is sent over long distances by being freshly regenerated at relay stations, as a baton is passed by relay racers during a long race.

Server   A computer that typically contains a large memory and that can deliver data over networks at high speeds. A modern descendant of the earlier model of mainframe computers that were time-shared.

Silicon   An element, atomic number 14 on the periodic table, which has properties that are well suited for the construction of integrated circuits.

Software   The suite of programs, including applications, operating systems, and system programs, that a computer executes.

Symbolic logic   See Boolean algebra.

TCP/IP   Transmission Control Protocol/Internet Protocol. See protocols.

Time-sharing   A method of using a large computer connected to a number of terminals. Because of the speeds of the computer in relation to the reaction time of the user, a person seated at a terminal has the impression that her or she has direct, sole access to the computer. (See also client-server.) An arrangement of networked computers that combines machines with high memory capacity and switching speeds with intelligent terminals.

Transistor   An electronic device that switches in a solid piece of material, typically silicon or germanium.

Vacuum tube   A device that switches electrons that move in a vacuum, excited by a hot filament.

Word   The set of binary digits processed together by a computer. A typical modern personal computer has a word length of 32 or 64 bits.

Workstation   A high-end personal computer with rich graphics, networking, and calculating ability.

World Wide Web   A program available on the Internet that allows those connected to the network to access information easily, whether it is stored locally or on another continent and regardless of the particular computer or server where it is located.