© 1991 Brian R. Page
Blast Off With BASIC
Glossary of Terms
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ABEND:
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A contraction
of abnormal end.
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ALGORITHM:
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A step-by-
step plan or formula
for solving a problem.
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ALPHANUMERIC:
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A mixture of alphabetic letters and numerals. An
alphanumeric keyboard
contains both letters
and numbers. An alphanumeric variable permits both letters and
numerals.
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ARTIFICIAL INTELLIGENCE:
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A computer program which, when
running, has the appearance of human intelligence.
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ASCII:
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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.
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BACKSLASH:
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The backslash character (\) is used in DOS commands to identify directories. In BASIC, backslash is
the symbol for integer
division.
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BANG:
-
A computer slang
term for the exclamation point (!).
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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.
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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.
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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.
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BLOWS UP:
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A program blows up when it unexpectedly ends in an error.
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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.
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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 such
as GOTO and GOSUB.
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BUG:
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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.
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BYTE:
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A collection of
eight bits.
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CLONE:
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An IBM compatible personal computer.
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CODE:
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A contraction of
source code. Contrast
with machine code.
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COLOR GRAPHICS ADAPTER (CGA):
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A hardware device needed to display
graphics on a color
screen.
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COMMAND:
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An instruction to BASIC or to
DOS. Since both BASIC
and DOS are programs,
the commands cause
these programs to do
something.
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CONSTANT:
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If the contents of a variable do
not change, that variable is called a constant.
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CENTRAL PROCESSING UNIT (CPU):
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The portion of computer hardware which
executes machine instructions such as add,
move, multiply, and
branch.
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CRASH:
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A computer
slang term for a, usually serious, programming error.
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CURSOR:
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The small
underscore character
(_), usually blinking,
that shows where on the
screen typed characters
would appear.
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DATA:
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The information to be processed by a
computer program. The
program itself is not data.
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DEBUGGING:
- The glorious process of finding and fixing errors in a program.
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DIRECTORY:
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A disk file
which lists other disk
files and directories.
The contents of directories are listed by the DOS DIR command.
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DISK DRIVE:
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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.
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DISKETTE:
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A floppy disk.
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DOS:
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The most popular
operating system for
personal computers.
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EDITOR:
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A program
which allows you to
type information or
programs into computer
files.
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EXTENSION:
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Disk file
names consist of two
parts. An eight-character filename and a
three-character extension. BASIC programs
usually have an extension of BAS.
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FIELD:
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The smallest
part of a DATA statement that can be assigned to a single
variable.
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FILE:
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A collection of
data or a program permanently stored on
disk, tape, or some
other media (paper
tape, punched cards).
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FILENAME:
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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.
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FLOPPY DISK:
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A flat
disk of plastic covered
with a magnetic coating
used to record and
store computer files.
Several types of floppy disks are available.
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FLOWCHART:
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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.
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FLOWER BOX:
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A rectangle made of asterisks.
Comments and instructions are often
put in flower boxes to
set them off from the
program statements.
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FREQUENCY:
-
Cycles per
second or Hertz (Hz) of
a sound tone.
FUNCTION: A BASIC command that causes the
BASIC interpreter to
run a subroutine.
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FUNCTION KEY:
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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.
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GRAPHICS MODE:
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The
ability of a personal
computer to display
graphics figures such
as circles and lines.
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HARD DISK:
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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.
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HARDWARE:
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The electronic components of a
computer.
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HERTZ (HZ):
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A unit of
measurement meaning cycles per second. Sound
frequencies are measured in Hertz.
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HEXADECIMAL:
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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.
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INPUT:
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Data supplied
to a computer program.
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INPUT/OUTPUT (I/O):
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The process or devices
used to supply input to
a computer program and
display or sound output.
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INSTRUCTION:
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A command
or statement that make
computer hardware do
something.
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INTERPRETER:
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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.
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INTEGER:
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A whole number.
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KILOBYTE (KB):
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1,024
bytes. Memory size is
often measured in kilobytes.
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LITERAL:
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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.
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LOOP:
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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.
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MACHINE CODE:
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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.
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MAINLINE ROUTINE:
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A
portion of a program
which controls the execution of the entire
program. The mainline
routine contains the
GOSUB statements calling the subroutines.
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MEGABYTE (MB):
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1,048,576 bytes. Memory size is often measured in megabytes.
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MEMORY:
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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.
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MODEM:
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A device which
allows personal computers to communicate over
telephone lines. A
communications program
must execute to use a
modem.
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MODULO:
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A BASIC operator which produces the
remainder left after a
division operation.
The command is MOD.
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MONITOR:
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A video display screen.
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MONOCHROME:
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A single
color video display
screen.
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MOUSE:
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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.
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NESTED LOOP:
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A loop
contained within another loop. The most
common in BASIC are
nested FOR-NEXT loops.
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OPERATING SYSTEM:
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A
computer program which
manages the personal
computer hardware. The operating system controls screen displays,
access to disk files,
and all input/output
operations.
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OPERATOR:
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A mathematical operation such as
addition (+), subtraction (-), multiplication (*), division (/ and \), greater than
(>), less than (<), not
equal (<>), and modulo
(MOD).
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OUTPUT:
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Data produced
by a computer program.
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PIXEL:
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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.
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RADIAN:
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A section of a
circle (arc) equal in
length to the radius.
Partial circles drawn
with the BASIC CIRCLE
command are specified
in radians.
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RAM:
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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.
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RESERVED WORDS:
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Words
and abbreviations which
have special meaning to
BASIC. Reserved words
cannot be used as variable names.
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RESOLUTION:
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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.
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ROM:
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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.
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ROOT:
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The beginning
directory on a disk.
The root directory may contain disk files or
pointers to other directories.
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ROUTINE:
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A collection
of BASIC statements
which work together as
a unit to perform a
specific task.
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SCROLL:
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The movement
of output on a video
screen display from
bottom to top as new lines are written at
the bottom.
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SOFTWARE:
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Computer
programs.
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SOURCE CODE:
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BASIC
statements. Source
code statements are
turned into machine
code by the BASIC interpreter.
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SPAGHETTI CODE:
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A
BASIC program, usually
using too many GOTO
statements, that is
difficult to understand
and follow.
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SPLAT:
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A computer
slang term for an asterisk (*).
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STATEMENT:
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A command
or function defined in
the BASIC language.
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STRING:
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A collection
of one or more characters.
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STRUCTURED PROGRAMMING:
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A way of writing programs which
emphasizes building
block subroutines controlled by a mainline
routine that uses few
GOTO statements. Contrast with spaghetti
code.
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SUBROUTINE:
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A collection of BASIC statements to perform a
special job. A subroutine is controlled by a
mainline routine.
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SYNTAX:
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The way in
which BASIC statements
are put together.
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TABLE:
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A collection of
data, either input or
output, that is arranged in rows and columns.
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TERMINAL:
-
A video display screen and keyboard that is usually
connected to a computer
network.
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TEXT MODE:
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The video
display mode in which
only characters may be
written to the screen.
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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.
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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.
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