A few months ago, someone mentioned in a forum that the Pacman arcade machine "didn't have a CPU". I found that really interesting for a 1980 coin-op.
Today I did some small research and found out that the first arcade game with a CPU was Gun Fight (1975) and the last Sega game not having a CPU was Monaco GP (1979).
I can only assume many (or most?) arcade games during the 70s didn't have a CPU or software and simply coded the game in the circuitry using "TTL (Translator to Translator Logic) based discrete logic circuits".
The process of developing these games on the circuitry must have been really interesting.
The original Playstation was a very special console. It opened console gaming to adult audiences and introduced some of the controller layouts and game IPs we still see today. But there was an underrated element that you see everytime you load a game: the bootup sound and animations. With the combination of those cool logos and sounds, even loading a Barbie game seemed like serious business.
5 years ago, a Youtube video explained how the bootup sound was made: it turns out they use 3 base sounds and mix it together several times (including some of them 2 or 3 times with changing speeds) to create this hypnotic theme.