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 program 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 command 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 END, STOP, LIST or NEW executed.key or the execution of the BASIC-Commands
Example of a BASIC program:
- Programming: a line can 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.
Explanation: This example demonstrates the abbreviation of the command PRINT by the token: '?'. In this way you can create a program line with 241 characters or 7 lines.
- After writing a BASIC command or a line number with commands, has to be pushed in order to store the line of commands in memory.
- Different commands within a line can be separated with a colon
- The name of variables must not consist of BASIC keywords (see BASIC keyword table below)
- Data and characters can only be assigned to variables with the correct properties.
- A BASIC program may only contain the line numbers from 0 to 63999 inclusive.
The BASIC version 2 contains the following 71 BASIC-Keywords:
|SPC||SQR||STATUS (short ST)||STEP||STOP||STR$|
|SYS||TAB||TAN||THEN||TIME (short TI)||TIME$ (short (TI$)|
- Basiswissen C64
- von Joachim Hänsel
- Westermann Verlag, ISBN 3-14-508810-6
- ein ausführliches Nachschlagewerk