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Atari Basic

Atari Basic

Getting starting on your programming journey does not have to be a difficult task. I began my adventure on the Atari 65xe in November of 1986. After debating whether to purchase a Commodore 64, I found a sale at Sears for this personal computer and the rest was history.

Basic (Beginners All Purpose Symbolic Instruction Code) was created in the early 70’s. Atari Basic utilizes an interpreter for their 8-bit machines via the 6502 chip. In the early years, the Atari personal computers required a cartridge to get Basic into memory since there was nothing devised for the chipset at that time. Often it was uncomfortable swapping out Basic with game cartridges, but that was how it started.Atari Basic originally stemmed from Microsoft’s 8K Basic.

The Atari Basic editor is the blue screen you are peering at. It consists of character spaces in an 8×8 matrix that fills each space in based on the binary value that exists there. The screen is made up of these tiny pixels on the display. Counting from left to right there are 40 characters in a row and about 22 in height.

Basic programming consists of logic that must follow a guideline. First there is an instruction table (commands) that is accepted by each type of Basic. It also consists of condition statements

Programming your Atari 65xe

Let’s get you started on some simple programming steps. Let’s have some fun and create a simple loop. Type in the lines below into either your Atari 65xe/800Xl, etc computer or using an Atari emulator online.

10 PRINT “I LOVE ATARI BASIC!!”
20 GOTO 10

Each statement must be separated by spaces. Atari Basic will complain and often throw syntax errors when you don’t follow the rules. Anyway after entering the program, on a new line type the word RUN and press the Return key.

You will instantly see the screen fill up with a slew of repeating messages that show ‘I LOVE ATARI BASIC!! You have just executed a loop that will print a message using line 1 and then the GOTO statement returns back to line 10 to print the message again and again. It will continue forever until you press the Break or Reset key.

Next to keep this interesting, let’s explore some of the built in Atari graphics modes. The mode you are looking at now is known as GRAPHICS 0. You can switch modes by changing the 0 to a higher number. Let’s explore GRAPHICS 1 as an example. This mode is smaller in size and the characters will be larger. Type in the following program below for fun.

10 GRAPHICS 1
20 PRINT #6;”How COOL IS This!”

When you want to change colors in a Graphics mode you can set the text characters in lowercase, uppercase, upper case inverse, and lower case inverse. This will select from 4 colors, black if you count the background. Later we will likely be exploring display list interrupts (DLI’s) that will allow you to access even more colors! This is known as multi color since combined bits can generate new colors in a single character area.

The Atari 65xe and other line of similar computers contain a wide variety of reserved keywords for the Basic language.  Eventually we will be exploring some programs, games, and applications, but for now I thought you may want to see a list of all the available words built into the token library.