Glossary of Terms

ABEND:

A contraction of abnormal end.

ALGORITHM:

A step-by-step plan or formula for solving a problem.

ALPHANUMERIC:

A mixture of alphabetic letters and numerals. An alphanumeric keyboard contains both letters and numbers. An alphanumeric variable permits both letters and numerals.

ARTIFICIAL INTELLIGENCE:

A computer program which, when running, has the appearance of human intelligence.

ASCII:

An acronym for American National Standard Code for Information Interchange. ASCII defines the combination of bits which represent each letter, numeral, and special character. An ASCII file is one which contains bytes of information which can be translated into readable output. Binary files, by contrast, consist of bit combination which do not necessarily represent ordinary characters.

BACKSLASH:

The backslash character (\) is used in DOS commands to identify directories. In BASIC, backslash is the symbol for integer division.

BANG:

A computer slang term for the exclamation point (!).

BASIC:

The letters in BASIC really stand for something: Beginner's All-purpose Symbolic Instruction Code. The language was developed at Dartmouth College in New Hampshire.

BINARY:

Having to do with the number two. A binary numbering system uses only two digits, zero and one. A binary search divides a group of items in half. Binary is useful in computing because the electronic devices can represent the zero and one as off and on switches.

BIT:

An abbreviation for binary digit. A bit is a single digit of a binary number. A bit can be either zero or one. In computer hardware, a bit is either off or on.

BLOWS UP:

A program blows up when it unexpectedly ends in an error.

BOOT:

To load an operating system into the memory of a personal computer and start it running. The most common operating system for personal computer is DOS.

BRANCH:

Ordinarily, BASIC programs execute one instruction at a time in line number order. A branch is a jump out of order. Branches are made with BASIC instructions suchas GOTO and GOSUB.

BUG:

A program error. The term arose in the early days of electronic computing when a real insect caused a problem to a United States Navy project.

BYTE:

A collection of eight bits.

CLONE:

An IBM compatible personal computer.

CODE:

A contraction of source code. Contrast with machine code.

COLOR GRAPHICS ADAPTER (CGA):

A hardware device needed to display graphics on a color screen.

COMMAND:

An instruction to BASIC or to DOS. Since both BASIC and DOS are programs, the commands cause these programs to do something.

CONSTANT:

If the contents of a variable do not change, that variable is called a constant.

CENTRAL PROCESSING UNIT (CPU):

The portion of computer hardware which executes machine instructions such as add, move, multiply, and branch.

CRASH:

A computer slang term for a, usually serious, programming error.

CURSOR:

The small underscore character (_), usually blinking, that shows where on the screen typed characters would appear.

DATA:

The information to be processed by a computer program. The program itself is not data.

DEBUGGING:

The glorious process of finding and fixing errors in a program.

DIRECTORY:

A disk file which lists other disk files and directories. The contents of directories are listed by the DOS DIR command.

DISK DRIVE:

A hardware device used to permanently store computer files. Two types are made. A floppy disk drive has small removable disks. A hard disk drive uses faster more delicate disks that are usually not removable.

DISKETTE:

A floppy disk.

DOS:

The most popular operating system for personal computers.

EDITOR:

A program which allows you to type information or programs into computer

EXTENSION:

Disk file names consist of two parts. An eight-character filename and a three-character extension. BASIC programs usually have an extension of BAS.

FIELD:

The smallest part of a DATA statement that can be assigned to a single variable.

FILE:

A collection of data or a program permanently stored on disk, tape, or some other media (paper tape, punched cards).

FILENAME:

The first part of a DOS file name. The filename may have up to eight characters. It may be followed by a dot (.) and a three-character extension.

FLOPPY DISK:

A flat disk of plastic covered with a magnetic coating used to record and store computer files. Several types of floppy disks are available.

FLOWCHART:

A diagram using boxes, diamonds, circles, ovals, and parallelograms to display the flow of control as a program executes. Flowcharts are very useful for understanding and planning the operation of a program.

FLOWER BOX:

A rectangle made of asterisks. Comments and instructions are often put in flower boxes to set them off from the program statements.

FREQUENCY:

Cycles per second or Hertz (Hz) of a sound tone. FUNCTION: A BASIC command that causes the BASIC interpreter to run a subroutine.

FUNCTION KEY:

The keys on a personal computer keyboard, usually numbered F1 through F10 or F12. Certain commands are usually assigned to function keys. Pressing the function key is a way to avoid typing the entire command.

GRAPHICS MODE:

The ability of a personal computer to display graphics figures such as circles and lines.

HARD DISK:

A type of magnetic storage disk that uses stiff plastic platters spinning rapidly. Hard disks have greater capacity than floppy disks and the information can be moved into computer memory more rapidly.

HARDWARE:

The electronic components of a computer.

HERTZ (HZ):

A unit of measurement meaning cycles per second. Sound frequencies are measured in Hertz.

HEXADECIMAL:

A base sixteen numbering system. Hexadecimal uses the numerals 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F. A single hexadecimal digit can represent four bits. Two hexadecimal digits represent a byte.

INPUT:

Data supplied to a computer program.

INPUT/OUTPUT (I/O):

The process or devices used to supply input to a computer program and display or sound output.

INSTRUCTION:

A command or statement that make computer hardware do something.

INTERPRETER:

When a program of BASIC statements is running, the BASIC interpreter converts each line, one at a time, into machine instructions for execution on the CPU. The interpreter performs the conversion from BASIC language statements which make sense to a human into machine instructions which are used by the hardware.

INTEGER:

A whole number.

KILOBYTE (KB):

1,024 bytes. Memory size is often measured in kilobytes.

LITERAL:

Words, letters, numerals, and special characters that are used exactly as they are written. No variable substitution or interpretation is done on literals. An example is anything contained within quotation marks on a PRINT statement.

LOOP:

The flow in a program which causes the same BASIC statements to be executed over and over. The FOR-NEXT BASIC statement is used to make loops. Some loops are accidental and result from program bugs.

MACHINE CODE:

Instructions which are executed by the personal computer CPU. Since BASIC statements cannot be understood by the CPU, the BASIC interpreter converts each BASIC statement into one or more machine code instructions.

MAINLINE ROUTINE:

A portion of a program which controls the execution of the entire program. The mainline routine contains the GOSUB statements calling the subroutines.

MEGABYTE (MB):

1,048,576 bytes. Memory size is often measured in megabytes.

MEMORY:

The computer hardware which stores data and programs. Data must be in memory to be used by a program. A program must be in memory in order to run. Computer memory stores all information in binary.

MODEM:

A device which allows personal computers to communicate over telephone lines. A communications program must execute to use a modem.

MODULO:

A BASIC operator which produces the remainder left after a division operation. The command is MOD.

MONITOR:

A video display screen.

MONOCHROME:

A single color video display screen.

MOUSE:

An input device. The mouse allows a person to move a cursor-like symbol around the screen to provide input for programs written to accept mouse input.

NESTED LOOP:

A loop contained within another loop. The most common in BASIC are nested FOR-NEXT loops.

OPERATING SYSTEM:

A computer program which manages the personal computer hardware. The operating system controls screen displays, access to disk files, and all input/output operations.

OPERATOR:

A mathematical operation such as addition (+), subtraction (-), multiplication (*), division (/ and \), greater than (>), less than (<), not equal (<>), and modulo (MOD).

OUTPUT:

Data produced by a computer program.

PIXEL:

A contraction of picture element. A pixel is a point on a display screen. It is the smallest portion that may be set or changed.

RADIAN:

A section of a circle (arc) equal in length to the radius. Partial circles drawn with the BASIC CIRCLE command are specified in radians.

RAM:

An abbreviation for Random Access Memory. RAM is memory which holds data and programs. The information is held in binary format. Any byte of RAM may be accessed by the computer. If power is removed from RAM, all information currently in memory is lost.

RESERVED WORDS:

Words and abbreviations which have special meaning to BASIC. Reserved words cannot be used as variable names.

RESOLUTION:

The ability of a video screen to display images. High resolution pictures can look even sharper than ordinary television. Low resolution images rough and blocky. The resolution provided with the BASIC SCREEN 1 command is actually rather poor.

ROM:

An abbreviation for Read Only Memory. Integrated circuits containing ROM hold their information even when the power is turned off. However, they cannot hold any new information. A personal computer cannot store any new data in ROM.

ROOT:

The beginning directory on a disk. The root directory may contain disk files or pointers to other directories.

ROUTINE:

A collection of BASIC statements which work together as a unit to perform a specific task.

SCROLL:

The movement of output on a video screen display from bottom to top as new lines are written at the bottom.

SOFTWARE:

Computer programs.

SOURCE CODE:

BASIC statements. Source code statements are turned into machine code by the BASIC interpreter.

SPAGHETTI CODE:

A BASIC program, usually using too many GOTO statements, that is difficult to understand and follow.

SPLAT:

A computer slang term for an asterisk (*).

STATEMENT:

A command or function defined in the BASIC language.

STRING:

A collection of one or more characters.

STRUCTURED PROGRAMMING:

A way of writing programs which emphasizes building block subroutines controlled by a mainline routine that uses few GOTO statements. Contrast with spaghetti code.

SUBROUTINE:

A collection of BASIC statements to perform a special job. A subroutine is controlled by a mainline routine.

SYNTAX:

The way in which BASIC statements are put together.

TABLE:

A collection of data, either input or output, that is arranged in rows and columns.

TERMINAL:

A video display screen and keyboard that is usually connected to a computer network.

TEXT MODE:

The video display mode in which only characters may be written to the screen.

USER FRIENDLY:

Programs which are easy to use are said to be user friendly. User friendly programs do not demand that the users be perfect. They can make assumptions about input, for example, not requiring that all letters of an answer by entered or that the input be all of upper case.

VARIABLE:

A name assigned to a location in memory that is used to hold data. Variables function like mailboxes. The variable name is the address, and the contents may be changed.