Personal Computer Origins: The Datapoint 2200

As We May Think, The Mother of All Demos, The Xerox Alto; all were breakthroughs in thinking about how to make the computer more personal. They were not, however, the true antecedents of the first ‘personal computers’. Instead, that line of descent runs through something much less visionary, capable or expensive: the humble computer terminal.

The terminal can claim this role in three ways. First, it was the computing device that users would most commonly interact with in the decade or so before the personal computer first appeared. Second, some terminals bore a strong physical resemblance to many popular early personal computers. Finally, it was the development of one particular terminal that led to the creation of both the architecture that would power the very first personal computers, and its successor, which would come to dominate in both personal computers and servers. In fact, we can trace the line of descent of that second architecture, now commonly known as x86 , which is still used today in the majority of the most powerful laptops, desktops and servers, from that terminal, the Datapoint 2200.

Despite some claims to the contrary, the more sophisticated terminals weren’t personal computers. As we’ll see, some designs, including the Datapoint 2200, were programmable, but they weren’t originally designed to be used as stand-alone computing devices. Some saw the possibility that they might be used as such, and they were even occasionally used as stand-alone devices. However, this was not widespread and their potential was never properly realised.

Even without this though, the Datapoint 2200 itself was an innovative and important device that represented a major step change over the device that it superseded: the teleprinter.

Loud and Dumb - The Teleprinter

In 1948, Manchester Baby, the first electronic programmable stored-program computer, had a Cathode Ray Tube (CRT) display that allowed users to peer directly into its 32-bit word memory. This worked because the CRT itself - what was known as a ‘Williams Tube’ - was memory.

In the decades that followed, though, the most common way of interacting directly with a computer was using a ‘teleprinter’. These devices usually included an alphanumeric keyboard, a printer and a means of reading data, from either paper tape or a magnetic disk. The Model 33 teleprinter, made by AT&T subsidiary Teletype¹ Corporation and introduced in 1963, was one of the most popular designs with ...