diy cpu

2 Articles

Most complex blinking light

2025 One Hertz Challenge: 16-Bit Tower Blinks At One Hertz

July 23, 2025 by 3 Comments

We’ve seen our share of blinking light projects around here; most are fairly straightforward small projects, but this entry to the 2025 One Hertz Challenge is the polar opposite of that approach. [Peter] sent in this awesome tower of 16bit relay CPU power blinking a light every second.

There’s a lot to take in on this project, so be sure to go look at the ongoing logs of the underlying 16-bit relay CPU project where [Peter] has been showing his progress in creating this clicking and clacking masterpiece. The relay CPU consists of a stack of 5 main levels: the top board is the main control board, the next level down figures out the address calculations for commands, under that is the arithmetic logic unit level, under the ALU is the output register where you’ll see a 220 V lamp blinking at 1 Hz, and finally at the base are a couple of microcontrollers used for a clock signal and memory. [Peter] included oscilloscope readings showing how even with the hundreds of moving parts going on, the light is blinking within 1% of its 1 Hz goal.

It’s worth noting that while [Peter] has the relay CPU blinking a light in this setup, the CPU has 19 commands to program it, enabling much more complex tasks. Thanks for the amazing-sounding entry from [Peter] for our One Hertz Challenge. Be sure to check out some of the other relay computers we’ve featured over the years for more clicking goodness.

2025 Hackaday One Hertz Challenge

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Another 74XX Series CPU

March 28, 2017 by 13 Comments

[Jack Eisenmann] is no stranger to building impressive DIY CPU’s on vast stretches of breadboard. This time [Jack] has done away with the seventeen breadboards he used in his last 8-bit computer and instead has gone a step further and designed a set of generously utilised PCB’s for the CPU. The result is the DUO Enterprise.

The CPU design is based around an 8-bit data bus and a 24-bit address bus. As usual, a minimal yet carefully chosen instruction set allows [Jack] to do all the heavy lifting in software as part of the compiler and operating system he is working on. There is no sign of a display yet, instead the computer communicates via a dumb terminal. We love the aluminum foil for shielding! Check out the video, below, to see what we mean.

Over the years, we have seen many of [Jack]’s other CPU builds featured on Hackaday. One of his first designs was a 4-bit CPU that could play many games on a LED matrix.Later he did a much more impressive 8-bit CPU along with analog video output and an OS ofcourse. It could even play pong. He even built a Single Instruction Set Computer (SISC).

His final goal with DUO Enterprise is to allow anyone to utilise its computing power by submitting programs and calculations. Heads up [Jack], our neural net needs training soon.

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