Powered machinery started the industrial revolution, and it was automation that kicked it up another notch in the 20th century. The ability for machines to make things by themselves spurred increased output and in turn boosted economic growth. The concept became widely popular for manufacturers to implement, as any change with serious economic benefit tends to do. Fast forward to today, and advanced robots and fancy machine vision systems running on powerful computers are the norm in modern factories which create the many wonderful products that we all purchase, use, and enjoy.
Once upon a time, though, things weren’t so sophisticated. [Nicola Cimmino] came to Hackaday Europe 2026 to tell us all about a remarkably simple 1-bit CPU that used to run factories.
Logic, But Make It Cheap!
Nicola Cimmino used to frequent a facility that used to recycle electronic waste, which sold old bits and pieces of hardware by the kilo. Many times, Nicola would pick up odd boards with an eye to repurposing components for future projects. Eventually, one unremarkable looking chip caught his attention—the Motorola MC14500B. This chip was rather unique, being a rather simple processor with just 16 instructions and a 1-bit data bus.
It’s worth examining the era in which this chip existed. Intel dropped the 4-bit 4004 in 1971, with the famous 8-bit 8080 landing in 1974. The Zilog Z80 came along in 1976, similarly an 8-bit design. And yet, when Motorola released the MC14500 in 1977, it landed with a rather slimline 1-bit design instead. Nicola notes that this likely came down to price, since populating a chip with more transistors cost more money quite significantly back in the 1970s. If the job could be done with less, it would make the part cheaper and thus more popular in the market. Bearing this out, Nicola explains that a 1976 Zilog Z80 used 8,500 transistors and cost around $200 USD, while an MC14500 used just 500 transistors and could be had in 1977 for the bargain price of just $5 USD.
Back in the mid-1970s, automation in industry often consisted of simple logic that was handled by cabinets full of relays. This took plenty of bulk, required hard-wiring everything, and also involved plenty of electromechanical parts that could wear out. Changing logic required manually rewiring things which could be fussy and tedious at the best of times. In those days, the Programmable Logic Controller was just coming into use, developed to be a reprogrammable system for industrial automation tasks that was more flexible and reconfigurable just by reprogramming it.
The MC14500 sprung up as a useful tool at this time, powering a great many programable industrial systems. It was designed to offer the bare minimum requirements for its application, while leaving extraneous hardware for designers to implement if and when it was needed. The architecture is simple enough for Nicola to explain with a single slide. The chip came with a 1-bit logic unit, operating with a result register, a 1-bit accumulator and the data bus. A minimal system could be lashed up with the MC14500, a counter, some external RAM or ROM (since none was onboard), and an input decoder and output latch of 8 bits each. This setup would only allow for doing combinational logic, since there is nowhere to store the current state of the system. However, hooking some outputs back to the inputs could allow for sequential logic, since it would allow for storing the current state of the system via those outputs. Nicola then steps through various other configurational changes to addressing and system architecture that could be made to optimize the MC14500 for use in different ways.
If you wanted to get to grips with using an MC14500 in industrial contexts, you would do well to pay attention to this talk, even if it came out some 40 years past the part’s heyday. Beyond the basic system architecture, Nicola explains how to use the limited instruction set, and how to get such a system executing simple programs in ladder logic, which remains somewhat of an industrial standard to this day. Beyond that, he steps up to more complex logic, like if/else conditionals and the use of some of the weirder instructions of the chip. He then shows off the hardware he built himself—both a breadboarded MC14500 setup built with wirewrap, and a more polished version on a custom PCB.
It’s not every day you get to learn about the nitty-gritty details of working with industrial hardware from the ground up. And yet, that’s exactly what Nicola brought to Hackaday Europe 2026. It’s an excellent primer on the topic, and also simply just good fun if you’re a fan of electronics and logic itself!
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This articles is written by : Nermeen Nabil Khear Abdelmalak
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