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At first glance, this tangle of wires, embedded components, and hand-soldered circuits might look like some kind of cyberpunk sculpture, but it’s actually a brilliant project. A dedicated enthusiast has just built a fully-fledged processor — yes, it’s not a debug board or a microcontroller, but a fully functional CPU with a full instruction set and memory addressing support, using only old memory chips and logic elements from the 8-bit era. It’s not intended to replace modern processors, but rather a “fun” DIY project called EPROMINT.
The creator of this amazing project, Majsterkowanie i nie tylko (abbreviated MINT, which stands for DIY and more), spent three months designing, wiring, programming, and documenting every detail of the processor architecture. The idea came from a simple experiment with old EPROM memory chips, which were originally used to control small external systems such as PWM dimmers or information displays. The simplicity of this experiment inspired him. If memory can be used to simulate basic logic, then building a full-fledged processor module may be within reach.
The hobbyist soon delved into circuit design, copying the architecture of classic 8-bit-era processors, particularly the Z80 that helped fuel the personal computer revolution. The result was a machine that might not look sophisticated, but ran a real instruction set, executed native assembly code, and responded to hardware interrupts just like a commercial processor.
The project began with the most fundamental component of any processor: the arithmetic logic unit (ALU). The first prototype was designed to perform simple addition operations, but its performance proved unstable and it was abandoned. It was replaced by a full-processor design to facilitate debugging. The design was later expanded to include a memory interface, an address bus controller controlled by a secondary ALU, and finally control logic to decode the opcodes and coordinate the entire data flow.
The software was also written entirely from scratch. About 2,000 lines of code were needed to define how the processor handled instructions, simplify data transfers within the system, and create test programs. All of this was created using a set of development tools adapted for early board models. The capabilities of the instruction set were far superior to those of older processors, including multiplication, division, trigonometric operations, and even bit-sequence processing. According to its creators, the processor was “on steroids.”
After connecting all the modules, the processor was first powered on with 250 mA. The design scheme, previously used for other experiments with memory chips, was adjusted to generate a complete set of instructions for the new processor. As shown in the figure above, the blinking LED serves as the first test program, and the second LED is connected and lights up when an interrupt is detected, indicating that the processor can handle external events even while executing instructions. It temporarily stops the current operation, handles the interrupt, and then continues execution from the interrupt point, just like a real processor.
The resulting processor filled four full-size breadboards, weighed over 500 grams, and contained over a kilometer of wire when unrolled. All logic operations were implemented using preprogrammable memory. So instead of using physical NAND gates made of silicon, the system sent an 8-bit input to an EPROM, which returned a result from a stored lookup table. Functions like data routing and instruction decoding relied on this approach. To demonstrate how the system worked, he hooked it up to a VFD display and wrote code to play The Matrix… or at least a low-resolution clip of it.
Unlike the hidden silicon inside modern SoCs, this processor’s execution path is completely exposed. Every clock cycle, every opcode, and every register change is visible and trackable. That’s the beauty of it. It’s DIY at its most authentic and punk rock. Watch this video and you’ll understand that the processors in our computers are like magic: billions of transistors dancing between tiny grains of sand, controlled by glass and pure human will. If building a simple processor seems daunting, imagine what a company like TSMC has accomplished in manufacturing. For similar feats in DIY projects, check out this unofficial Steam Controller 2 made from a glued-together Steam Deck, or see how the RTX 5090 was reborn.
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Hassam Nasir is a passionate hardware enthusiast with years of experience as a technical editor and writer specializing in in-depth CPU comparisons and hardware news. In his spare time, he can be found bending tubes for his ever-improving liquid-cooled gaming rig or just testing the latest CPUs and graphics cards for fun.
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Post time: Jul-16-2025