Rebuilding The First Digital Personal Computer

When thinking of the first PCs, most of us might imagine something like the Apple I or the TRS-80. But even before that, there were a set of computers that often had no keyboard, or recognizable display beyond a few blinking lights. [Artem Kalinchuk] is attempting to recreate one of these very early digital computers, the Kenbak-1, using as many period-correct parts as possible.

Considered by many to be the world’s first personal computer, the Kenbak-1 was an 8-bit machine with 256 bytes of memory, using TTL integrated circuits for the logic as there was no commercially available microprocessor available at the time it was designed. For [Artem]’s build, most of these parts can still be sourced including the 7400-series chips and carbon resistors although the shift registers were a bit of a challenge to find. A custom PCB was built to replicate the original, and with all the parts in order it’s ready to be assembled and put into a case which was built using the drawings for the original unit.

Although [Artem] plans to build a period-correct linear power supply for this computer, right now he’s using a modern switching power supply for testing. The only other major components that are different are the status lamps, in this case switched to LEDs because he wasn’t able to source incandescent bulbs that drew low enough current, and the switches which he’s replaced with MX-style keys. We’ll stay tuned as he builds and tests this over the course of several videos, but in the meantime if you’re curious how this early computer actually worked we featured an emulator for it a while back.

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The Man Who Didn’t Invent The Personal Computer

[John Blankenbaker] did not invent the personal computer. Museums, computer historians, and authors have other realities in mind when they say [John]’s invention, the KENBAK-1, was the first electronic, commercially available computer that was not a kit, and available to the general population.

In a way, it’s almost to the KENBAK’s detriment that it is labelled the first personal computer. It was, after all, a computer from before the age of the microprocessor. It is possibly the simplest machine ever sold and an architecturally unique machine that has more in common with the ENIAC than any other machine built in the last thirty years..

The story of the creation of this ancient computer has never been told until now. [John], a surprisingly spry octogenarian, told the story of his career and the development of the first personal computer at the Vintage Computer Festival East last month. This is his story of not inventing the personal computer.

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Recreating The First PC

If you’re looking for a simple Ardunio project, why not replicate the first personal computer?

After discovering the Arduino, [Mark] realized recreating really old computers would be a fun project. An Altair 8800 was on the table, but the sheer number of blinkenlights, switches and the Intel 8080 CPU made that a fairly difficult project. After a bit of searching, [Mark] discovered the Kenbak-1, widely regarded as the first personal computer. The Kenbak also had the added bonus of having a very minimal I/O compliment and was built entirely with TTL components.

Since the Kenbak-1 is an extremely simple computer, [Mark]’s build ended up being fairly minimal. The schematic is only an ATmega328, a few shift registers and a real-time clock for a few added features the OG computer didn’t have. The completed build is programmed by pushing buttons to enter machine code into the mega’s RAM and then executed. [Mark] has a few programs already figured out – a program that counts in binary, a ‘Cylon eye’ and a BCD and binary clock. While the Kenbak-uno doesn’t have the awesome vintage case of the original, it’s still a remarkable build.

Check out the videos after the break for a walk through.

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