Many 70s arcade games didn't have a CPU or software: they used "discrete logic"

[cwpab]

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.

Sources:

https://paleotronic.com/2018/10/05/no-software-required-how-atari-made-its-first-video-games-without-a-computer/

https://fi.edu/en/blog/transistors-microprocessors-classic-arcade-game-was-first-and-last-generation

https://en.wikipedia.org/wiki/Monaco_GP_(video_game)#Development_and_release

https://emulation.gametechwiki.com/index.php/Discrete_circuitry-based_arcade_games (thesee are the discrete cirtuitry supported games by MAME)

https://web.archive.org/web/20181231035300/https://mamedev.emulab.it/undumped/index.php?title=Discrete#Namco (these are just the undocumented ones in 2018)

[cwpab]

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.

Correction: This paragraph should say "A few months ago, someone mentioned in a forum that the Breakout arcade machine "didn't have a CPU". I found that really interesting for a 1976 coin-op."

[Skunkfish]

Thanks for the correction! I was questioning my memory as I could have sworn Pac-Man used a Z80!

[lmimmfn]

Thanks for the correction! I was questioning my memory as I could have sworn Pac-Man used a Z80!

Says here from mame code that pacman uses a Z80 https://www.walkofmind.com/programming/pie/hardware.htm

[Bryce]

I regularly restore old Flipper machines from the 60's. They didn't even have TTL logic, the entire game, lights, controls and score keeping was done with a "field" of free wired relays and light bulbs!

Bryce.

[Gryzor]

I regularly restore old Flipper machines from the 60's. They didn't even have TTL logic, the entire game, lights, controls and score keeping was done with a "field" of free wired relays and light bulbs!

Bryce.

A few years back I restored someone's arcade cab and, quite honestly I  was surprised I got it to work (AND have it sort of dual boot its original board and a Pandora box 😁). He then asked me to take a look at a really old flipper machine he had. I told him there was no way I could bring it back up to working order, save finding some spares and the right people to really work on it. He insisted. I opened it up. Saw the labyrinth of cables and wires (and most probably a few dead rodents and bugs) laughing at me. Noped the fuck off as quick as I could.

[cwpab]

I wish I could buy any arcade machine on the market today.

I would probably buy Sega Rally or something.

EDIT: Oh, it looks like you can in some specialized pages... Sega Rally only costs €4,000 here (you probably need to live on the UK): https://arcadedirect.co.uk/sega-rally-1-arcade-machine/

[robcfg]

But PacMan is indeed Z80 based: https://en.wikipedia.org/wiki/Pac-Man

The original arcade system board had one Z80A processor, running at 3.072 Mhz, 16 kbyte of ROM and 3 kbyte of static RAM.

That is also why @SyX could port it to the CPC using the original roms.

[Bryce]

I regularly restore old Flipper machines from the 60's. They didn't even have TTL logic, the entire game, lights, controls and score keeping was done with a "field" of free wired relays and light bulbs!

Bryce.

A few years back I restored someone's arcade cab and, quite honestly I  was surprised I got it to work (AND have it sort of dual boot its original board and a Pandora box 😁). He then asked me to take a look at a really old flipper machine he had. I told him there was no way I could bring it back up to working order, save finding some spares and the right people to really work on it. He insisted. I opened it up. Saw the labyrinth of cables and wires (and most probably a few dead rodents and bugs) laughing at me. Noped the fuck off as quick as I could.

Hopefully one of the older one's with open relays and mechanical counters like this....

Bryce.

(Random Pictures from internet, not my repair).

[Devlin]

There's a great two-parter series on Youtube by Technology Connections about how the old wired relay nests work in old pinball machines here - I always recommend these when the topic comes up, they're very interesting!

[Gryzor]

I regularly restore old Flipper machines from the 60's. They didn't even have TTL logic, the entire game, lights, controls and score keeping was done with a "field" of free wired relays and light bulbs!

Bryce.

A few years back I restored someone's arcade cab and, quite honestly I  was surprised I got it to work (AND have it sort of dual boot its original board and a Pandora box 😁). He then asked me to take a look at a really old flipper machine he had. I told him there was no way I could bring it back up to working order, save finding some spares and the right people to really work on it. He insisted. I opened it up. Saw the labyrinth of cables and wires (and most probably a few dead rodents and bugs) laughing at me. Noped the fuck off as quick as I could.

Hopefully one of the older one's with open relays and mechanical counters like this....

Bryce.

(Random Pictures from internet, not my repair).

Something like this, but quite more chaotic! 

[retro space]

The story for Breakout is rather remarkable, as Jobs fooled Woz over the Atari deal and almost held the entire fee Atari paid, and the fact that Atari could not grasp the way the circuit by Woz functioned, so they made a way more complex board themselves.