In a few museums around the world, there lies the special experience of seeing some of the earliest computers. These room-filling monsters have multiple racks of vacuum tubes that are kept working by the dedication and care of their volunteer maintainers. A visit to the primordial vacuum tube computer, Colossus at Bletchley Park, UK, led [Mike] on the path towards designing an entirely new one. He thinks it’s the first to see the light of day in over five decades. ENA, the Electron tube New Automatic Computer, is the result.
It uses 550 Soviet 6N3P double triodes, and its 8-bit Von Neumann architecture is constructed from the tubes wired up as 5-input NOR gates. ROM is a diode matrix, and RAM comes courtesy of reed relays. The whole thing is assembled as eleven PCBs on a wall-mounted frame, with a console that holds the piece de resistance, a display made from an array of LEDs. A Pong game is in development, meanwhile the machine makes an impressive room heater.