Module __Chapter_2

Statements

Statements describe what the program does. The original Dartmouth BASIC was separated into a compiler and operating system with statements like GOTO and PRINT for the compiled language and commands like SAVE and LIST for controlling the system. 64K BASIC is a unique implementation where everything is compiled and executed by a virtual machine. There are no commands, everything is a statement.

Statements tend to be short and it’s common to put multiple statements on a single line. Use a colon : to separate statements. This works in both direct and indirect modes.

FOR I = 1 TO 10 : PRINT I : NEXT I

Statement words can never be used in variable names. 64K BASIC will insert spaces to help you when you accidentally include a word in a variable name.

LET BONK = 1
10 LET B ON K = 1

Statements need to be properly formatted with the information they need. Angled brackets <> are used to indicate required items. Square brackets [] are used to indicate optional items. Ellipsis ... indicate items that may repeat. Vertical bars | separate mutually exclusive options. All letters and punctuation not in brackets are required.

Modules

CLEAR

CLEAR [...]

CLS

CLS

CONT

CONT

DATA

DATA <literal>[,<literal>...]

DEF

DEF FN<name>(<argument>[,<argument>...]) = <expression>

DEFTYPE

DEFINT/SNG/DBL/STR <range of letters>

DELETE

DELETE [<line number range>]

DIM

DIM <variable name>(<dimensions>)[,...]

END

END

ERASE

ERASE [<array variable>][,<array variable>...]

FOR

FOR <variable>=<x> TO <y> [STEP <z>]

GOSUB

GOSUB <line number>

GOTO

GOTO <line number>

IF

IF <expression> THEN <statements> [ELSE <statements>]

INPUT

INPUT [,]["<prompt string>";]<variable>[,<variable>...]

LET

[LET] <variable>=<expression>

LIST

LIST [<line number range>]

LOAD

LOAD <filename>

MID

[LET] MID$(<string>,n[,m])=<expression>

NEW

NEW

NEXT

NEXT [<variable>][,<variable>...]

ON

ON expression <GOTO|GOSUB> <line>[,<line>...]

PRINT

PRINT [<list of expressions>]

READ

READ <variable>[,<variable>...]

REM

REM [<anything>] or ' [<anything>]

RENUM

RENUM [<new number>][,<old number>][,<increment>]

RESTORE

RESTORE [<line number>]

RUN

RUN [<line number>|<filename>]

SAVE

SAVE <filename>

STOP

STOP

SWAP

SWAP <variable>,<variable>

TRON

TRON | TROFF

WHILE

WHILE <expression> : WEND