The PCB here was marked as a 'Gum' machine and is from a gambling machine that instead of paying out money would dispense chewing gum as prizes
Other games with 'Gum' in the title also exist, see 'Chewing Gum' and 'Royal Gum' in other drivers for example, these were likely used with similar chewing gum dispensers.
Weren't the first slotmachines generally camouflaged as chewing gum vending machines with additional game to circumvent anti-gambling laws? AFAIK that's why fruit symbols (illustrating available chewing gum flavours) found their way into slotmachines (and from there eventually into the Mr.Do! videogame series).
The "Pucman" and "Invaders" on "4 En Raya" hardware seem to be the only such fascade videogames those are IMO actually fun to play (beside too fast clearing score counter and small glitches). In opposite e.g. "Pacman"/"Super Pacman" (both the same game) on "Cherry Master" hardware are simply boring (likely not even made intentionally bad). Graphics and sound are just uninspiring work-to-rule programming. E.g. the single coloured ghosts don't flash when the pill timer runs out, which makes it hard to play.
If I remember well, bartop arcade machines with small CRT existed (seen in a used goods dealer TV show and likely a game machine catalogue), those had a dozen or so selectable games with simple graphics including skill, quiz and chance (card etc.) games. I am not sure if the latter count as gambling or if payout was possible (likely only won credits for continue play). These were not one facade videogame to hide a "main" gambling feature but simply meant as multigame machines, hence all games had similar (often low) quality.
