Rediscovering the MCU Magic of the 70s with Nicola Cimmino’s PLC14500 Nano Trainer

The PLC14500 Nano is a retro-style trainer kit intended for the user to familiarize with the Motorola MC14500 1-bit ICU (Industrial Control Unit), PLCs, and Ladder Logic. Over 50 LEDs on the board show the status of the system bus and registers, giving great insight into how the programs are executed. When not in use, it displays a captivating light show on your desk.

Programming a microcontroller has become relatively easy these days thanks to modern tools, software libraries, and user-friendly development environments. But that was not the case just a few decades ago. So, when [Nicola Cimmino] became curious about the Motorola MC14500 (a 1-bit controller from the 1970s), he could think of no better way than making a trainer kit out of it. Thus, the PLC14500 Nano was introduced to the world. It’s not only a great-looking retro project; it also helps people understand how the old processors and ladder logic work.

While going through the schematic and BOM of the project, I found a sneaky Arduino Nano hiding under the board, and I think that’s the reason why it was named PLC14500 Nano. But after careful investigation, I found out that the Arduino Nano works as a bootloader and handles the communication with the PC, nothing more than that.

Nicola also provides an assembler that lets you write code in ASM before programming the binary to the ICU. You can find all the documents, tools, schematic, and PCB on Nicola Cimmino’s GitHub Page.

As a hardware engineer, this project was really cool because it was a fusion of retro and modern hardware together. But the coolest part is that it’s OSHW Certified, meaning the design is completely open-source for anyone who wants to build one at home. And if you want to support Nicola, he’s also selling kits on Tindie.

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