The Early Days: The History of Interactive Computing

Prologue: Turing

1. Project Whirlwind

2. TX-0

3. DEC Founded

4. PDP-1

5. PDP-8

6. PDP-10

7. PDP-11

8. ARPANET

Looking back

1936 — Turing's universal machine

1945 — Project Whirlwind begins

1951 — Whirlwind operational

1956 — TX-0: transistors arrive

1957 — DEC founded

1960 — PDP-1 ships

1962 — Spacewar!

1965 — PDP-8: Father of the PC and microcontrollers

1968 — PDP-10: the hackable mainframe

1970 — PDP-11: Home of Unix

1972 — ARPANET: Origin of the internet

1974 — Microprocessor era dawns

Most people will mention ENIAC or perhaps the IBM<br>System/360 as examples of early computers. Room-filling machines fed by punch cards, producing payroll runs and scientific calculations. Yes, that was a big part<br>of the story — but it is not our story. The computers we actually use in our daily lives escaped very early on from that path.

Alongside the mainframes, a different strand of computing was taking shape.<br>Where you could use the computer as a tool you could sit<br>down with and interact with . Where you didn't wait hours for a batch job to<br>come back. This is<br>the strand that led to Windows, Linux, Android, the smartphone in<br>your pocket. And to the microcontroller in your dishwasher.

This page is an introduction to that story. It covers the key machines and some of the people. It wants to tell where our computers, and the fundamental ideas behind them, came from.

We admit: this is our perspective. We're Obsolescence Guaranteed, and our goal is to relive these machines hands-on, through the replicas we make of them. We apologise for any oversight or bias. We can't help it, we like our bias.

The Enigma Machine and our replica, scale 2:3.

Click for a Youtube on Enigma and the Bletchley Park Bombe

"Breaking Enigma was one of the top triggers at the dawn of the computer age."

Prologue: Alan Turing

Before computers, there was the question: what is computation? In 1936,<br>Alan Turing, then a 24-year-old Cambridge mathematician, answered this with a<br>thought experiment. An imaginary machine that could read and write symbols on an<br>infinite tape, following simple rules. The "Universal Turing Machine" could, in<br>principle, perform any calculation that any computer ever could. It was a purely<br>theoretical construct, but defined the boundary of what was possible.

A decade later, Turing was at Bletchley Park, building real machines to break the<br>German Enigma cipher. The Bombes (and later the Colossus) were special-purpose<br>devices, but proved that electronic computing was practical.<br>Turing himself went on to design the ACE (Automatic Computing Engine)<br>at the National Physical Laboratory, one of the first stored-program computers.

Turing's influence on the interactive computing story is fundamental.<br>He showed that a machine could be general-purpose. Not just a calculator, but a tool for thinking.

Turing's ideas were not theoretical. The Pilot ACE , built at the National Physical Laboratory in 1950, was the fastest computer in the world: processing at around 1 MHz, a phenomenal speed for its time. And in 1950, Turing published another seminal paper — "Computing Machinery and Intelligence" — which asked a deceptively simple question: Can machines think? He proposed the Imitation Game , now known as the Turing Test. That question is still unanswered, but interactive computing is what made it worth asking in the first place.

Project Whirlwind — the first interactive computer, 1951

Project Whirlwind — the operator's room

"Whirlwind first showed that computers could be interactive tools, not just<br>calculating engines. It was the first machine that waited for you."

Design for the planned Whirlwind replica

We need to cut down from building-sized to panel-sized, alas

1. Project Whirlwind — The First Interactive Computer

In 1945, the United States Navy asked MIT to build a better flight simulator. They wanted a machine that could model an aircraft in<br>real time, calculating aerodynamic forces fast enough that a pilot could<br>fly it by feel. This was a completely insane request. No computer had ever been<br>built to work at human speed. It became a very successful failure.

Jay Forrester, the young MIT engineer put in charge, did not know this was impossible.<br>He built Whirlwind . Running in 1951, was a revelation. It had a CRT display , you could watch it draw in vectors. It had a light pen , switches and buttons for direct input: the first computer designed to interact with a human being in real time.<br>Every other computer of the era ran batch jobs: hand over your stack of punch<br>cards and come back later. Whirlwind sat there and talked back to you.

Along the way, Forrester and his team invented magnetic core memory . Ferrite rings threaded with wires could hold data (actually, even without power). Core<br>memory remained the dominant random-access memory technology for two decades, and<br>is still used in some spacecraft today. It was born because vacuum tube memory<br>kept...