Nice score, Mike!
I grew up playing games on my Atari 800. I spent sooo many hours with Astro Chase, Boulder Dash, & Bristles (and Flip & Flop to a lesser extent). Fernando Herrera was a genius!
Being intimate w/ the Atari 8-bit computers, I have deduced that, when you put a credit in your Max-a-Flex, it resets the Atari computer & enables the control panel input & starts the timer. At the end of the timer, I imagine that it will reset the Atari again & disable control panel input at the same time.
The Option, Select, & Start buttons mimic those on the computer. They're for selecting # of players, difficulty, starting level, etc. Those always differed from game to game, depending on what the programmer wanted.
Enjoy!
-Jason