This is the most elusive (or Ultra Rare) PC-50x-type cartridge there is for any SD-050/070/090 Pong-Cartridge game systems. In fact, it is so rare that there is only 1 picture of the cartridge in 20 years of surfing the web (yep, started surfing in 1996) and the web site "Pong-Picture-Page" has this picture:
It's the one in the right-up corner: "PC-508 - Fundamental"
In 20 years, i have never seen one except in this photo, so is it rare ? Let me say it is ALMOST as rare as to find a real POLYBIUS arcade....HA! (hope you all know that Polybius is an urban legend). But even if it's the rarest game cartridge for SD-050 (and clones) Pong systems, it was also released for two other Pong systems: The Poppy 9015 and the Unimex Mark IX (both in the 9015-family).
For the Poppy 9015, is is called: "Schiess-und Sportwettkampf" (model 9015H) which translate to in Engligh "Shooting and Sports Competition" and for the Unimex Mark IX, it is called: "Schiess-Ball Spiele" (model Nr.907) and in English "Shooting-Ball Games".
Here's some pictures from Pong-Picture-Page (hope Adrian won't mind):
And here's a picture with the label in English (from an Ebay seller):
So...if you check out those two cartridge labels, this game cartridge has six games: Tennis, Hockey, Handball, Squash, Target 1 and Target 2 and those two carts comes with a light gun....HUMMM.
I thought for a couple of years that the PC-508 had an AY-3-8550 and it has the same games as the AY-3-8500 but you can move the paddles vertically and horizontaly as any Pong systems (SD-050 and clones) have joysticks, and would have been logical as the AY-3-8550 is also a rare game chip to find.
But after researching for any 1st and 2nd generation games for 20 years, i finally found my answer to which game chips are inside those PC-508, so before i reveal the answer, here's some pictures of different Pong systems:
So if you check any of those boxes especially in the right-down corner, you should see this:
Those are fuzzy pictures as i tried to manify them but you can eventually see something: the paddles are only showing vertical mouvement! So here's a better picture (taken from the GI 1978 catalog):
Same screenshot! So here you have it folks, the PC-508 Fundamental cartridge has really a AY-3-8500 game chip! Talk about weird! The rarest cartridge but with the most commun game chip!! Go figure! We can assume that General Instrument back them wanted to liquidate their AY-3-8500 stock so they released this last cartridge but it's so $&?$ rare to find!
Anyway, just get a PC-501 cart (aka Supersports) and mofify the board so that you can use a AY-3-8500 instead of a AY-3-8610 and you got yourself a homebrew PC-508...like yeah...who's in his right mind will do this! LOL!!!
So that's another mystery solved gang! Scooooobbyyy-Doooo!!! (i know...i need some vacation fast!-lol!)