As in most academic studies, the understanding of the terminology used in the field is a major part of the learning process. The words used in the field of microcomputers are unique, colorful, sometimes descriptive, and sometimes obscure. They cannot be found in any commercially available dictionary at the present time. The Institute of Electrical and Electronics Engineers (IEEE), New York, has been engaged in a major project begun by Dr. Martin Weik in 1979, of the creation of a comprehensive dictionary of computer terminology. This writer has assisted the IEEE by serving on the Computer Graphics subgroup which is part of eight major groups of scores of users and scholars now helping to compile the meanings for approximately 5900 identified technical words used in relation to computers. The final "draft" of the dictionary is scheduled to be available soon.

The following terms are commonly used general computer words or are particularly applicable to microcomputer graphics and should be learned by the student.

Abort: The voluntary ending of a program or operation of a program in progress; most DOS-based programs respond to ^C (hold down the <Ctrl> key and type the letter C), or ^X or ^S or ^<Break> to abort the program or operation. Many Windows programs use the <Esc> key to abort.

Address: The complete descriptive location of a file on a hard or floppy disk, e.g., "C:\ACAD\DWG\XYZ.DWG" is the address of an AutoCAD drawing file called "XYZ" which is located within sub-directory "DWG" of directory "ACAD" on the "C:" disk drive.

Alphanumeric: Pertaining to the characters (letters, numbers, punctuation marks, and signs) used by a computer.

Application program: See "program"

ASCII: The acronym for American Standard Code for Information Interchange, a widely used system for encoding letters, numbers, punctuation marks, and signs as binary numbers which can then be manipulated by a computer.

Aspect Ratio: The height to width ratio of an image on an output device, which may be different from the actual height to width of the object represented; varies with the type of graphics card used and the design of the output device itself.

Attribute: Verbal information associated with a graphic object.

Baud Rate: The number of bits transmitted per second; also called "BPS"

Binary: Having two components or possible states, e.g., either "on" or "off."

Binary Code: A system for representing things by a combination of two symbols, such as one and zero, TRUE and FALSE, or the presence or absence of voltage.

Binary number system: A number system which uses two as its base and expresses numbers as a series of zeros and ones.

Bit: The smallest unit of information in a computer, equivalent to a single zero or one. The word "bit" is also a contraction of "binary digit."

BOM: Bill of Materials. A list of information generated by the computer program from data attached to blocks of graphic data in a drawing file, by using "attributes". Examples are door schedules, window schedules, room finish schedules, column schedules, quantity survey, and cost estimates.

Boot up: Turn on the computer in order to load the disk operating system (DOS) into memory; see also "warm boot" and "cold boot".

Buffer: Computer memory reserved for temporary storage of data.

Bug: A mistake in a computer program.

Byte: A sequence of eight bits treated as a unit for computation or storage. Each key on a computer keyboard is represented by one byte of information.

CAD: Computer Aided Drafting.

CAAD: Computer Aided Architectural Design

CADD: Computer Aided Drafting and Design.

CAM: Computer Aided Manufacturing.

CIM: Computer Integrated Manufacturing

Central Processing Unit (CPU): The part of a computer which interprets and executes instructions.

Character: A letter, number, punctuation mark, or any other symbol which is generated on the monitor screen by pressing a key on the keyboard.

Circuit board: The plastic board on which electronics circuits are mounted.

Circular (or Polar) Array: Multiple copies of an object which are drawn in a circular (or part of a circular) pattern, with equal spacing between each.

Command: A specific word or other entry, input to a computer software program, to provide an instruction and initiate a function of the program.

Computer: A programmable machine that accepts, processes, and displays data.

Computer Terminal: See "Terminal".

Compiler: A computer program that translates another program written in high level language (i.e., more understandable by a normal user) into machine code, so that the program can run on the computer faster. For instance, AutoCad normally "compiles" its menu and operating program language by means of a built-in compiler which comes with AutoCad in order to speed up its operation.

Configuration: Providing a set-up for a software program for use with specific peripheral devices, by installing the proper software drivers into the program, by the user; configuration need only be done once for each specific combination of hardware used.

Control keys: See "Function keys."

Crash: The premature end of a computer program due to a hardware fault, a bug, or error in the program.

Cross hair: Horizontal and vertical crossed lines appearing on the monitor screen, which designate the current working point of the drawing as located by the digitizer or mouse pointer.

CRT: Cathode Ray Tube, normally called the "monitor".

Cursor: The movable blinking dash or spot of light that indicates a point of action or attention on the computer monitor screen, where the next alphanumeric character will appear on the screen upon one's depressing a key on the keyboard.

Data: Information in the form of bits and bytes which can be stored on disks, displayed in understandable form on a monitor, and used by a computer.

Database: A computerized set of files, containing comprehensive information on any subject; as applied to a computer program type, any program which will allow listing of information in a structured way, and allow sorting the information by name, date, length, etc., and allow extracting information in similar groups; in AutoCad, the list of all steps used to create a drawing file and the list of vectors (endpoints and center points) of all lines, arcs, and circles which make up the drawing.

Data extraction: The process of producing a Bill of Materials report.

Data processing: Operations carried out on data; mostly used in conjunction with computerized accounting and bookkeeping.

Dedicated: Designed for one specific operation.

Default: An assumption made by a computer program when it is not given a specific instruction by a user. For instance, in AutoCAD, the "default" linetype and color is continuous and white, unless instructed otherwise.

Digital: Pertaining to the representation or transmission of data by discrete (i.e., on or off) signals

Digitize: To convert a hardcopy of a drawing to a graphic computer form by using a digitizer tablet; to represent data in digital, or discrete form.

Digitizer: A graphic input device plugged into a computer which allows drawing of lines, arcs, and circles in a drawing program, consisting of a "tablet" and a "pointer" (either a stylus or a mouse).

Digitizer tablet: See "digitizer".

Disk: A round magnetized plate, usually made of plastic or metal, organized into concentric tracks and pie-shaped sectors for storing electronic data.

Disk drive: The electro-mechanical mechanism which rotates a disk and reads or records electronic data from or onto that disk.

Display: Another word for "monitor" or "display monitor" or "video display terminal".

DOS: Acronym for "Disk Operating System" (see "Operating System" below).

Dot matrix: A rectangular grid of dots from which any alpha-numeric character may be constructed, usually in reference to the type of print head which a printer has.

Driver: A computer program which instructs a computer to reformat and recode data in such a way that it can be used by a printer, a digitizer tablet, a plotter, or other peripheral device, and which controls the communication to that device.

Electronics: The science or use of electron-flow devices, such as vacuum tubes, and transistors, with no moving parts.

Electrons: Particles of electrical charge.

Entity: Basic graphic unit used to create a drawing, such as a line, an arc, a circle, or a line of text.

Error message: A statement in words displayed by a computer on the monitor when it has detected an erroneous instruction or malfunction within its own system.

Extension: The last one to three characters which follow a period in a file name, such as .DWG, or .PIC.

File: An organized collection of electronic data, which is given a unique name of from one to eight alpha-numeric characters so that it can be stored and retrieved from a disk in order to be operated on.

Fillet: A curve of any radius determined by the user which joins two non-parallel lines.

Floppy disk: A small (5-1/4" in diameter) flexible disk coated with magnetic material used to store electronic data; also called "floppy" or "floppy diskette."

Font: The design of a lettering style.

Function keys: Special keys on the keyboard, marked "F1" through "F10" which are defined by every software program as having a special meaning and may effect several operations at once by means of pressing only one key. For instance, the key "F1" in AutoCAD "flips" the screen from a graphic mode to a text mode, whereas "F1" in Wordstar can be defined by the user to mark the beginning of a block.

Gigabyte: A thousand million bytes, or a thousand megabytes (ten to the ninth power).

Grid: A rectangular and regular array of dots spaced at any distance determined by the user, used to reference fixed locations on a drawing.

Hacker: Someone who loves to experiment with computers.

Hard copy: A printout on paper or a plot of a drawing on paper or mylar of computer data or a file.

Hardware: The physical apparatus (e.g., CPU, monitor, keyboard, plotter, printer, etc.) of a computer system.

Hatching: The filling of an enclosed area of a drawing with a textured pattern; traditionally called poche in architecture.

Input: Information fed into a computer by a user.

Input device: Any hardware device used to enter data into a computer, e.g., keyboard, digitizer, mouse.

Input/Output (I/O) port: An outlet on a computer circuit board for plugging in input or output hardware devices such as printers, plotters, digitizers, keyboards, etc.

Joystick: A graphic input device plugged into a computer which is a small box with a movable stick in it which can be moved in all directions. The movement direction and magnitude are sensed by the computer and a relative displacement of the cross hair is made which allows drawing of lines, arcs, and circles in a drawing program. Joysticks are not normally used in most professional graphics programs due to their relative inaccuracy and somewhat artificial feel in relation to manual drawing techniques.

Kilobyte (KB): 1,024 bytes (2 to the 10th power), used to express data storage quantities or computer memory capacity, also called simply "KB" or "K".

Layer: A grouping of related graphic entities, in a manner similar to an overlay drafting sheet, e.g., a layer of a plan drawing could contain all entities which represent walls, another layer can contain all entities which represent doors, another windows, another dimensions, another text, etc. Each layer can be made visible or invisible at any time, thereby allowing them to be changed, plotted, copied, etc.

Macro: A single command which can be described in a program to initiate the performance of a group of commands.

Mainframe computer: The largest type of computer hardware, usually capable of serving many users simultaneously, with a processing speed of about 100 times that of a typical micro-computer.

Megabyte (MB): A million bytes, or a thousand kilobytes; also called simply "MB", "M", "a meg", and sometimes "a ton".

Memory: The data storage facilities of a computer, i.e. internal storage, as opposed to external storage such as disks or tapes.

Menu: A list of options offered by a program, displayed on the monitor for the user to choose from. A program which makes use of this system is called "menu-driven," such as Wordstar and AutoCAD.

Microcomputer: A desktop or portable computer in which the CPU is contained on a single chip known as a microprocessor. Microcomputers are meant for a single user, often called a "home" or "personal" computer; IBM PC, PC-XT, and PC-AT are examples.

Minicomputer: A mid-sized computer smaller than a mainframe, but larger than a microcomputer, and usually with more memory than a microcomputer.

Mirroring: The process of creating a mirror image of a drawing or a part of a drawing along a specified axis.

Modem: A device which can be connected to a computer and to a telephone line that enables data to be transferred between computers. The word is derived from the process which is used to effect the transfer of data, that is, "MOdulator/DEModulator."

Monitor: A television screen-like output device connected to a computer for displaying electronic data in visual and understandable form; also called "display," "display monitor," "screen," VDT (for "video display terminal" and CRT (for "cathode ray tube").

Mother board: A large circuit board into which several smaller boards can be plugged; in the IBM PC microcomputer family, the horizontally mounted board which is at the bottom of the computer.

Mouse: A small, handheld graphic input device plugged into a computer which is moved around on a surface. The movement direction and magnitude is sensed by the computer and a relative displacement of the cross hair is made which allows drawing of lines, arcs, and circles in a drawing program. Mice come in two general varieties, "roller ball" mice, such as Microsoft Mouse, and "Optical" mice which work by reflection of a low powered laser beam such as Mouse Systems Mouse.

Network: The linking together of several computer systems.

Nybble: Half a byte, or four bits; sometimes spelled "Nibble".

Operating system: A computer program used to control, assist, or supervise all other programs which run on a computer system; known as "DOS" to most users.

Output: The data returned by a computer either directly to the user in the form of some kind of visual appearance on the monitor, or to some kind of electronic storage device such as a floppy disk.

Package: Another name for a computer program, and including the instructions or documentation needed to use it.

Pan: Moving of the point of view of the user with relation to the drawing to show a different part of the drawing on the monitor screen, analogous to moving a camera viewfinder from right to left or up and down; panning does not change the apparent size of a drawing, only the part displayed on the screen.

Parameter: Values input by a program user to specify certain specific conditions.

Peripheral: A device, such as a printer or digitizer tablet, or plotter, which is plugged into a microcomputer.

Pixel: The smallest area of the monitor screen which can be independently highlighted and colored; looks like a very small square dot on the screen; short for "picture element"; the more pixels which can be displayed across a monitor screen and from top to bottom of the screen, the better the visual "resolution" of any picture or data displayed on it.

Plotter: A robotic machine which drives a pen to draw a computerized drawing file on paper, vellum, or mylar.

Pointer: A digitizer or mouse.

Port: An outlet on a computer circuit board for plugging in hardware devices such as printers, plotters, digitizers, keyboards, etc.

Primitive: See "entity".

Program: A series of detailed instructions for performing some operation or solving some problem by computer.

Programmable: Capable of responding to instructions and thus of performing a variety of tasks.

Prompt: A message or symbol displayed by a software program on the monitor screen which informs the user that the program is ready for input.

Mouse: A hand held device similar in appearance to a mouse, with buttons and attached to a digitizer, used to input points in a drawing.

RAM: An acronym for "Random Access Memory" which is a form of temporary, internal electronic data storage whose contents can be retrieved and altered by the user.

Raster: The electron beam that draws a video picture by sweeping across the monitor screen and creating a series of thin lines; also, a type of video graphics drawing which can be described by means of pixel illumination only, as opposed to a geometrical construction.

Read: The process by which the CPU of a computer examines electronic data in memory or transfers data to memory from an input medium such as a floppy disk.

Rectangular array: Multiple copies of an object which are drawn in a rectangular pattern, arranged in rows and columns, with equal spacing between each.

Repaint: Process of redrawing a display image on the monitor screen to eliminate deleted entities or to clean up the image.

Resolution: The fineness of detail in a video display on the monitor, dependent on the size and number of pixels on the screen. Resolution varies with the type of color graphics card and type and size of monitor used in a microcomputer system.

ROM: An acronym for "Read Only Memory" which is permanent factory-supplied internal memory containing data or operating instructions that cannot be altered by the user.

Rubberbanding: In drawing a line in a graphics computer program, the program automatically creates a "stretchable" and movable line running from the first endpoint of the line picked (indicated) by the program user, to the current cursor position, determined by the location of the "pointer" (the digitizer puck, stylus, or mouse); rubberbanding a line gives the user a visual image of how the line would look at every new position of the pointer.

Run: The execution or carrying out of a program by a computer.

Scrolling: Vertical movement of text lines on the monitor screen.

Semiconductor: A solid crystalline substance such as silicon whose electrical conductivity falls between that of good conductors like metals and that of poor conductors like insulators (such as rubber), and can be changed in nature of conductivity between simulating these two types of materials.

Shell: Capability of accessing a software program without exiting the program one is working in.

Silicon: The most abundant element in the world from which transistors and computer chips are made.

Silicon Valley: An area of California south of San Francisco that is the center of the semi-conductor production industry in the United States.

Soft copy: Electronic data and information displayed on a monitor screen, recorded on a disk, or on a tape, or in any form that is not a hard copy, i.e., a printout on paper.

Software: Instructions or programs in the form of electronic data stored on disks that enable a computer to do useful work, as contrasted with "hardware" or the physical apparatus of a computer system; also called a "program."

Source program: A program written in a "source language" such as BASIC or Pascal, or LISP, that has to be interpreted or "compiled" into machine code before a computer can run it.

Stylus: A hand held device similar in appearance to a pen, attached to a digitizer tablet, and with a tip which can be depressed against the tablet to "pick" points in the drawing, and a button on the side of the barrel which has varying uses depending on the program it is used with.

Tablet: The flat horizontal portion of a digitizer, on which the puck or stylus are placed to pick points in a drawing; see "digitizer".

Tablet overlay: A paper or plastic sheet which is placed on top of the digitizer tablet, and containing a menu of various programmatic functions which can be made to be input to a program when picked by the user.

Terminal: A device composed of a keyboard for putting data into a computer, along with a monitor and printer for receiving data from a computer, normally located in a place remote from the computer itself. This term is used mostly in conjunction with mainframe or minicomputers.

Thumbwheels: A horizontally aligned and a vertically aligned wheels which are mounted to a computer keyboard and connected to a computer. The movement direction and magnitude of each wheel in relation to the other is sensed by the computer and a relative displacement of the cross hair is made which allows drawing of lines, arcs, and circles in a drawing program. Thumbwheels were the earliest type of input device for mainframe and minicomputer graphics systems and are not normally used at this time in the microcomputer systems due to the difficulty and unnatural feel of the tool.

Transistor: A semiconductor device used as a switch or amplifier of electronic signals.

Vacuum Tube: A closed glass tube with conductors inside it and pins at one end for connecting to electrical circuit wiring, used as the earliest form of electronic switch, eventually replaced by the transistor.

Window: A visual box displayed on the monitor screen made by a computer program user to mark certain portion of a drawing to look at it more closely, move it, erase it, copy it, etc.; in another sense, the term "window" refers to a part of the monitor screen which is used to display certain information; in the program "Symphony", for instance, there may be several windows displayed at one time which each show a piece of the total database or spreadsheet.

Word processor: A dedicated computer, or a computer program which allows text to be entered and edited on the monitor screen through the keyboard before it is printed on paper. Such files which are created may be stored and re-used in the future for other purposes.

Write: The process by which a computer records data in memory, external storage or display devices.

Zoom: The enlarging or reducing of a view of a monitor screen image, either to magnify a portion of the drawing, or to see all of the drawing at one time; can be expressed as "zoom in" to magnify, or "zoom out" to make drawing appear smaller; zooming does not change the actual size of any entities, only the apparent size on the screen.