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Why Atari?
It may seem crazy to spend any time at all on the Atari 2600, a gaming system that was inroduced over 40 years ago. It was techologically current in 1977, but today you would have a hard time finding any electronic gadget in your home that doesn't have vastly more processing power - and by "gadget" I mean even devices like your thermostat. So, why spend time on it?
It's fascinating to see how much the programmers of the time were able to do with so little. The 2600 featured a tiny 128 bytes of RAM. And that is not a typo - it featured 128 bytes, not kilobytes or megabytes, just bytes. Having such a tiny amount of RAM presents a challenge to the game programmer - just how and where do you represent the contents of the screen? The 2600 solution was the custom graphics chip, the TIA (Television Interface Adapter), which contained thematically tiny bits of memory to represent the display content. The catch was that there was only enough memory to represent the contents of a single scan line, which brings up the second interesting thing about the 2600.
Racing the Beam
The 2600 was designed to the analog television technology of the day, which featured a cathode ray tube painting a scren with electron beams. The game software controlled the TIA which, in turn, controlled the action of the beam. This action is fast with each scan line taking about 56 microseconds to paint the line with a 22 mircosecond break between scanlines. This is very little time for a processor that requires 3-4 microseconds for most instructions. Even though there is a much longer break between picture frames, the big picture is that the game software had a very limited amount of time for game logic - so limited that game develpers spent a large fraction of their time counting the clock cycles of the code they had written. This is why game development on the 2600 has been dubbed "Racing the Beam."
The Atari Lives On Here
The second reason that you might be interested is that the Atari 2600 continues to live - not only on the game consoles of enthusiasts but on this site and elsewhere on the web. So, in the links below, you can find some simple programs for the 2600 as well as a number of full-blown games. You could modify the example programs and run them or even write your own game from scatch.
Learn 6502 Assembly Language
The final reason for spending time on this platform is the prospect of writing 6502 assembler! If you have never coded assembly language , the 6502 is a great place to start. Comapred to modern CPU's, it is incredibly simple and is a great place learn the concepts.