I love retro-style microprocessor trainer boards. These were common back when microprocessors were still relatively new, and trainer boards were a good way to learn how to use them. Essentially, they were single-board computers, but they were often kits that had to be assembled (good soldering practice!) and they often had features specific to their mission of teaching, rather than trying to be general-purpose single-board computers. The PLC14500-Nano 1-bit Single Board Computer Kit is taking that same idea of a microcontroller trainer board and applying it to the unique Motorola MC14500 1-bit CMOS processor.
“How can a 1-bit computer be useful?”, you may be thinking. Well, while it technically is Turing-complete, that wasn’t the intended purpose behind these chips. They were designed to replace relay logic and other electromechanical control systems where the functions are relatively simple. Because so much of the design depends on the choice of external chips (it doesn’t even contain a program counter — this is contained in an external chip!) it was an extremely flexible and cost-effective design that was briefly very popular before microcontrollers came along and took over.
So what can you do with this kit? Well, first of all, just like trainer boards from the 1970s, you have to solder it together yourself. This is a great opportunity to study the schematic and learn how the system is designed. Once it’s built, you have a whopping 256 bytes of RAM to write any programs you want! Well, any program that can fit in 256 bytes, anyway. It has 7 inputs and outputs that could be connected to just about anything (assuming you remove the buttons/LEDs that are there by default). It even has control of the clock, allowing you to single-step through your program, which is an important feature on a trainer board. This way, you can see the system working one step at a time. With an oscilloscope probe in hand, you can learn an awful lot about microprocessor internals.
Yes, there’s a sneaky modern intruder — an Arduino Nano is there simply to make development easier by providing a way to upload code to the board. The designer recommends soldering it to the back of the board so as not to ruin the illusion of a retro machine! This would make a great gift for anyone keen on learning about processor technology or any hacker who is interested in oddball, unique designs.