The OPERATING SYSTEM is in charge of "organizing" all the memory in your machine for various tasks. It also looks at what characters you type on the keyboard and puts them onto the screen, plus a whole number of other functions. The OPERATING SYSTEM can be thought of as the "intelligence and personality" of the Commodore 64 (or any computer for that matter). So when you turn on your Commodore 64, the OPERATING SYSTEM takes control of your machine, and after it has done its housework, it then says:

   READY.

The OPERATING SYSTEM of the Commodore 64 then allows you to type on the keyboard, and use the built-in SCREEN EDITOR on the Commodore 64. The SCREEN EDITOR allows you to move the cursor, DELete, INSert, etc., and is, in fact, only one part of the operating system that is built in for your convenience.

All of the commands that are available in CBM BASIC are simply recognized by another huge machine language program built into your Commodore 64. This huge program "RUNs" the appropriate piece of machine language depending on which CBM BASIC command is being executed. This program is called the BASIC INTERPRETER, because it interprets each command, one by one, unless it encounters a command it does not understand, and then the familiar message appears:

   ?SYNTAX ERROR

   READY.

WHAT DOES MACHINE CODE LOOK LIKE?

You should be familiar with the PEEK and POKE commands in the CBM BASIC language for changing memory locations. You've probably used them for graphics on the screen, and for sound effects. Each memory location has its own number which identifies it. This number is known as the "address" of a memory location. If you imagine the memory in the Commodore 64 as a street of buildings, then the number on each door is, of course, the address. Now let's look at which parts of the street are used for what purposes.