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Half-ton handbuilt CPU heads to Centre for Computing History

1,000,000 hand-soldered joints, £40k spent, just about fits in one lorry

A 42,000-transistor CPU weighing half a ton and built by hand from full-sized components has been installed at the Centre for Computing History in Cambridge, England.

James Newman’s Megaprocessor, a super-sized CPU big enough to walk through, was born as a result of a 2012 work discussion.

"There was a conversation at work about that time when we were talking about debugging something and someone remarked it would be easier if we had an LED on a signal," he explained to The Register in 2015.

Speaking to the Centre for Computing History last week, Newman added: “This all started with me wanting to learn about transistors. Things got out of hand!”

His ultimate goal other than the pure satisfaction of building the thing and getting it running, as El Reg reported in June this year, was to show the public how computers work by blowing the CPU up to a human-viewable scale. To do this he used modern transistors and LEDs – 42,300 of the former and 10,548 of the latter – all hand-soldered into place. The LEDs help visually trace the paths of data through the giant processor.

Youtube Video

The processor itself uses 15,300 of the transistors, though Newman notes that “a fair proportion of these are used to drive the LEDs”, of which 8,500 are connected to the core. The core itself occupies a whopping 15 square metres, which compares slightly unfavourably to the 33mm2 of Intel’s venerable 8086.

RAM and programmable ROM both weigh in at 256 bytes each, while the 500W power draw is mostly down to the juice needed to light the LEDs.

As for clock speed, Newman reckons it’s somewhere around 20kHz. Folk wanting to write programs for it can check out the documentation on the official Megaprocessor website.

His matter-of-fact page on faults and problems he encountered during the four years it took to construct and solder the Megaprocessor is here, including a mystery problem later traced to Henry the Hoover. ®

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