Pong-based Units

From Atari to many other publishers, these were mostly Pong and pong-based units, or stand-alone gaming consoles that didn't have interchangable cartridges of any kind, not even swapping switch cards or the like. The upside is they weren't extremely expensive though the dawn of cartridges would show it was much cheaper than getting a system with 3 games and then getting a new system with 3 more different games.