Two Secret Games Discovered on Vintage Coleco Telestar Pong Chip
Dave found two examples of “secret” abandoned games on a vintage Pong chip while creating a Pong game from scratch.
It isn’t uncommon for distributors to publish video games with unused assets still included in the data. In our modern era, that is often done to support future DLC (downloadable content). But just as often, those unused assets are the unintentional remnants of development. They could be for features that were abandoned during development or even entire games. Dave found two examples of “secret” abandoned games on a vintage Pong chip while creating a Pong game from scratch.
Dave’s project began with a Coleco Telestar, which is one of a series of dedicated video game consoles from the late ‘70s that came with three built-in games: hockey, handball, and tennis. The console used a General Instrument AY-3-8500 “Pong on a chip” IC that was manufactured in massive quantities for use in knockoff Pong consoles (of which there were many at the time). That concept is almost unimaginable today, but the chip had almost everything necessary to run the onboard games. The console manufacturer only had to slap the chip on a PCB and shove it into their own branded enclosure.
Because General Instrument designed the AY-3-8500 for this purpose, it is possible for anyone to build their own custom Pong console from scratch on a breadboard. That is exactly what Dave set out to do and his video thoroughly documents the journey. But the AY-3-8500 doesn’t handle everything and needs some additional components to make a playable game. For instance, it needs a clock signal for timing and it outputs video elements (similar to what we might call sprites) to separate pins. Dave used an Arduino Uno development board to generate the clock signal and a 4072 CMOS chip with OR gates to collect the video inputs into one signal to output composite video.
Dave constructed the player input paddles using simple potentiometers. A hardwired rotary switch lets the players select which of the three games to play. And this is where Dave discovered something interesting: two shooting games that weren’t enabled on the original Coleco Telestar. It is likely those are the target and skeet games playable on later versions of the console like the Coleco Telestar Ranger. They require a special light gun accessory that wasn’t available with the original Coleco Telestar, but it is interesting to see that the games were right there are on chip and simply inaccessible to players. By modifying the game selection switch, anyone then or now could start those hidden games.
