C64-Commands

From C64-Wiki

The Commodore 64 has its own Operating System (short: OS), which is Commodore-BASIC V2.0 (Beginner's All-purpose Symbolic Instruction Code Version 2). After turning on the C64, there are 38911 free characters (i.e.: Bytes) in the RAM-Memory (main memory). In a wider sense, all C64-Commands are BASIC-Commands.

The BASIC-Interpreter reports READY. and the blinking cursor shows the user that the computer is ready for input. After a BASIC-Command is typed in correctly, the command will be executed; otherwise an error-message will be reported, followed by READY. and a blinking cursor again.

The BASIC-Commands can be entered directly (example: RUN to start a BASIC_Program) or with one or more line numbers - the last is called BASIC-Program. The BASIC-Interpreter recognises via the line numbers that a program is written. The command LIST will show the program listing. Initially, the BASIC-program or a programm listing is only temporarily stored in memory (RAM). When a BASIC-program is to be stored permanently, it must be saved on a data media like datasette or disk with the comman SAVE. After saving, a BASIC-Program can be loaded into memory with the BASIC-Command LOAD.

The BASIC-Interpreter works off a BASIC-Program line by line from the first line number (0) until the last line number (63999). The program is interrupted by any BASIC-Errors, the Template:keykey or the execution of the BASIC-Commands END, STOP, LIST or NEW executed.

Example of a BASIC-Program:
10 PRINT "Hello, I'm the Commodore 64 - What is your name ";:INPUT A$
20 PRINT "Hello " A$
30 END

• Programming: a line can be have 80 characters maximum (40 characters over 2 lines) - any further characters are ignored.
• Excess length lines can be generated by using abbreviations (tokens) of the BASIC-Commands or with compilers. The editing of excess length lines is a problem.

1?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?
:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?

Explanation: This example demonstrates the abbreviation of the command PRINT by the token: '?'. In this way you can create a programe line with 241 characters or 7 lines.

• After writing a BASIC-Command or a line number with commands Template:key has to be pushed in order store the line of commands to memory.
• DIfferent commands within a line can be separated with a colon (:).
• The name of variables may not consist of BASIC-keywords (see BASIC-keyword-table below)
• Data and characters can be assigned to variables with the adequate properties.
• A BASIC-Program may only contain the line numbers from 0 to 63999 inclusive.

[edit] BASIC-Keywords Overview

The BASIC Version 2 contains the following 71 BASIC-Keywords:

ABS	AND	ASC	ATN	CHR$	CLOSE
CLR	CMD	CONT	COS	DATA	DEF
DIM	END	EXP	FN	FOR	FRE
GET	GET#	GOSUB	GOTO	IF	INPUT
INPUT#	INT	LEFT$	LEN	LET	LIST
LOAD	LOG	MID$	NEW	NEXT	NOT
ON	OPEN	OR	PEEK	POKE	POS
PRINT	PRINT#	READ	REM	RESTORE	RETURN
RIGHT$	RND	RUN	SAVE	SGN	SIN
SPC(	SQR	STATUS (short ST)	STEP	STOP	STR$
SYS	TAB(	TAN	THEN	TIME (short TI)	TIME$ (short (TI$)
TO	USR	VAL	VERIFY	WAIT

[edit] Literature

German Books

• Basiswissen C64

von Joachim Hänsel

Westermann Verlag, ISBN 3-14-508810-6

ein ausführliches Nachschlagewerk

[edit] Remark

This article in the German-version of www.C64-Wiki.de was "article of the month" in June 2006 and "article of the year" in 2006