Task: Try BASIC Programming on the Atari 2600
Needed: BASIC Programming cartridge, keyboard controllers, Atari 2600
Time: 15-30 minutes
Introduction
Programming in BASIC on the Atari 2600 is one of the most interesting things I have done with that machine. The BASIC Programming cartridge was released by Atari in 1979 and was programmed by Warren Robinett. Having programmed a game for the 2600 in assembly language, I am fascinated by the challenge of making a cartridge that allowed users to do some very simple things with BASIC. The challenges included no keyboard and access to only 128 bytes of total RAM of which on 64 bytes could actually be used by BASIC programs. Given these constraints, the BASIC Programming UI was actually not bad.
When you boot BASIC you are presented with a screen that is divided into six different sections. At the top is the STATUS section that shows you how much memory is left (i.e. the number symbols left that can be used) and how fast the program is executing (i.e. the speed). Second is the PROGRAM where you type in the BASIC commands. Note that your programs are limited to about 10 lines of code given the memory constraints. Third is the STACK that shows the progress of the program. Fourth is the VARIABLES section that shows the values of the variables as the program is running. Fifth is the OUTPUT section that displays any output from code such as the PRINT statement. Finally, a GRAPHICS section can be displayed with two colored squares that can be moved around by setting X (HOR) and Y (VER) variables to values from 0 to 99.
Atari made keyboard controllers for games like Star Raiders and for BASIC Programming. These came with overlays that provide all the different options for switching between the different sections of the screen, for entering BASIC commands, and for executing and halting programs. I found these to be really easy to use. There is a color button that toggles between four different colors that map onto the different options on the overlay. This provides lots of different options across the two keyboard controllers.
Below is a photo of BASIC Programming running on an Atari 2600. Also shown is a short video of a running three-line BASIC program that moves the res square diagonally down the screen.
Instructions
Step 1 – Purchase what you need
The BASIC Programming cartridge is fairly common and can be purchased on eBay for around $10 loose. There were about five for sale at this price at the time of this post. A boxed version sells for more like $20 to $40. If you get the boxed version make sure it comes with the controller overlays that you will need to make this work. The keyboard controllers can also be found loose on eBay for around $10. There were about 10 of these for sale at the time of this post.
Step 2 – Type in a program and run it!
Instructions and sample programs to enter can be found in the in the BASIC Programming manual. There are more than a few example programs to try. Below is a video of this in action!
Comments
This was way more fun than I expected. There isn’t much you can do with this, but I found it really interesting to see and imagine who the programmer made this work given the obvious constraints of the system. Here is a fun post from someone who took this for a spin. Note the comments about the memory leak!
