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Program Configuration
Section 7-4
7-4 Program Configuration
A BASIC program consists of commands, statements, and functions.
Basic Statements designate and control the flow of programs and are gener-
ally used in program lines within a program. Statements are executed by the
RUN command and can be executed directly from a terminal without line num-
bers.
Basic Commands are usually entered from the command line and control
operations external to the program, such as printing and listing. Commands
are executed when the ASCII Unit is in Command Mode. They cannot be
used in the program and executed with the RUN command.
Functions are self-contained programs which accept one or more argu-
ments, perform predefined calculations, and return a result(s). There are pre-
defined BASIC functions for arithmetic and string operations as well as user-
defined functions. Functions cannot be used on their own, but must be com-
bined with statements.
7-4-1 Command Execution Modes
There are two modes for executing commands.
Command Mode By entering a command and pressing the Enter Key when “>” is displayed on
the terminal screen, the command will be immediately executed. The com-
mand input standby condition is called Command Mode.
Program Mode A line is created by inputting a BASIC command with a line number at the
beginning and pressing the Enter Key. A program consists of a collection of
these lines. The execution of commands using these programs is called Pro-
gram Mode.
7-4-2 Programs, Lines, and Statements
A BASIC program consists of a collection of lines. A line is made up of one or
more statements, and a statement can contain a function.
Line Numbers • Every BASIC program line begins with a line number. (When there is no
line number, the program is executed directly.)
BASIC Language
Commands
Statements
Functions
User-defined
functions
Built-in functions
General statements
Device control statements
BASIC functions
Arithmetic functions
Character string functions
Special functions
Statement
Program
Line
Line
Line
Statement
Line No.
Comment
Separated by colons (:)
Statement
Statement
Function