To Load Program

We can load a saved program by following these steps.

i-                   Press the F3 key or type LOAD command.

ii-                 Type the name of the existing file in quotes.

iii-               Press ENTER key.

iv-                The file will be loaded.

Create and Save the Program

The GW-BASIC program is a file that contains instructions for computer. In GW-BASIC program lines have this format” Line# statement (s)”

Line#  is an unsigned integer in the range from 0 to 65529 .A line cannot have more than 255 characters.

Statement (s) is any valid GW-BASIC statement .There can be more than one statement in a line. Each statement must be separated by colon sign ( : ).

To save program :

We can save program by using this procedure.

i-                   Press the F4 key or type SAVE command.

ii-                 Type a valid name (in quotes) for the program and press ENTER key and program will be save.

Rules for Naming a Variable

1-     A Variable name cannot be more than 40 characters.

2-     The name of Variable may contain alphabets (both lower case and upper case) numbers and decimal points.

3-     The first character in name of Variable must be an Alphabet.

4-     Key /Reserved words of BASIC cannot be used as Variables.

5-     Blank space is not allowed in names of Variables.

6-     Last character of variable name should indicate the type of variable.

VARIABLES

In GW-BASIV Variables are the names of Memory Cells which are used to store program’s input data and its computational results during the execution of program.

Every Variable used in BASIC must have a name. There are some rules for naming a Variable.

Character Set of BASIC

The following are the characters valid for GW-BASIC

Character	Meaning
=	Equal sign or assignment symbol
+	Plus sign or string concatenation
-	minus sign
*	Asterisk or multiplication symbol
/	Slash or division symbol
^	Carter, exponentiation symbol, or CTRL key
(	Left parenthesis
)	Right parenthesis
%	Percentage or integer declaration
#	Number sign or double precision declaration
	Exclamation point or single precision declaration
[	Left bracket
]	Right bracket
,	Comma
“”	Double quotation marks or string delimiter
.	Period ,dot or decimal point
‘	Single quotation mark, apostrophe, or remark indicator
;	Semi colon or carriage return suppressor
:	Colon or line statement delimiter
&	Ampersand or descriptor for hexadecimal and octal number
?	Question mark
<	Less than symbol
>	Greater than symbol
\	Backslash or integer division symbol
@	“At” sign
__	Underscore
BACK SPACE	Deletes last character typed
ESC	Erases the current line from the screen
TAB	Moves print position to next tab stop. Tab stops are every eight columns.
ENTER	Terminates input to a line and moves cursor to beginning of the next line ,or executes  statement in direct mode.

Reserved /KEY Words in BASIC

In BASIC there are some reserved or Key words  which have predefined uses and cannot be used for any other purpose. These words cannot be used as variable names. some Key words are IF, ELSE, THEN, WHILE.

Writing Programs in GW-BASIC

GW-BASIC provides a IDE (Integrated Development Environment ) where we can write ,edit, save ,load and execute  BASIC programs.

As you could see in above picture that there are some options at bottom of the picture that are F1 List, F2 Run, F3 Load,  F4 Save,  F5 Cont, F6 LPT1, F7 TRON, F8 TROFF,  F9 KEY AND F10 SCREEN.

Key	Command	Description
F1	LIST	Displays the program listing from RAM
F2	RUN	Execute the program if available
F3	LOAD	Read a program in to RAM from Disk
F4	SAVE	Write a program from RAM to disk
F5	CONT	Continues program after STOP command
F6	LPTI	Send the out put to the Printer
F7	TRON	Displays each line number when program is running
F8	TROFF	Shuts off the TRON function
F9	KEY	Used with different Key functions.
F10	SCREEN 0,0,0	Changes the screen with default settings.