According to PC Gamer, Grinberg managed to boot the Debian Linux kernel on a 4-bit Intel 4004 processor, the first commercially manufactured microprocessor. With just 2,600 transistors, the 4004 is extremely limited in operations and lacks hardware interrupts.

To achieve this, Grinberg emulated a MIPS R3000 processor on the 4004, using a custom circuit board and period-correct components.

In fact, it's far too basic a chip to run Linux and this is where Grinberg got creative. With a RAM target of just 4 kB, he coded up a program to emulate a MIPS R3000 processor on the 4004. That particular chip is from the same era as the original version of Linux so it was a natural choice for the emulation task, though it was far from easy to achieve.

Despite a  five per cent overclock, the 790 kHz clock speed meant the kernel took 4.76 days to boot. This is about as long as my ten year old budget Android phone before I replaced it with this nice new budget Android phone.

While impractical, Grinberg’s project showcases his ingenuity and determination. His previous work includes creating firmware for a Def Con badge used to run a Doom port.