Today if you want to program a microcontroller, there’s a good chance you’ll turn to a dev board like those made by Arduino and write everything in a C-like language or MicroPython before transferring it to the chip to run. This is of course is all well and good, but misses the very low level understanding that our programming ancestors had when they had to literally flip switches as inputs. One could also argue that our modern programming techniques add a few unnecessary steps for very simple programs (like blinking an LED), where things could otherwise be programmed with a few button presses.
If you find this idea fascinating — and you’d prefer not to dig out an actual '70s-era computer — hacker “GClown25” has just the thing with his “4-bit” microcontroller board. Interface for the device is via a pair of programming buttons, along with a reset. Program steps are advanced with button two, while button one changes the actual value. The reset button then causes it to leave programming mode and actually run the program.
Everything is outlined on the project’s GitHub page, with a simple “Blinki” example and project files if you’d like to build your own. While it functions as a binary computer, the MCU used here is an ATmega4809 processor, which emulates this low-leven functionality. Be sure to also check it out in action below, as GClown25 shows how to program it as a binary counter.