I/O to the players was done through these tiny terminals:
These are obviously very primitive input/output devices, but do not forget that we didn’t have video displays, mice, or joysticks. These were pretty good for 1978.
Each tiny terminal had eighteen keys arranged in a 5 x 4 grid; and standard 7-segment LEDs arranged in two rows of eight characters each. Each of these 7-segment LEDs also had a decimal point, making 8 total LEDs per character.
They had no internal circuitry; a ribbon cable with 22 lines connected each tiny terminal to the I/O board. Here’s something to make you blanch: the connector from the tiny terminals to the KIM-1 box:
Please remember that I was just learning how to solder. The thing worked, which was good enough for me. I’m still not very good with a soldering iron, but after 45 years, I’m certainly better than this.
Much to my surprise, these things have internal boards. Here’s a photo of one of these boards:
Here’s the schematic that I found for this board:
