A brief history of the computer

One of the very first computers to use ICs was the Apollo Guidance Computer, introduced into NASA’s Apollo rocket programme in 1966. Weighing more than 30 kilos, the electronic brain that first steered man to the moon had roughly 4k of RAM, 72kB of ROM and ran at just over 1MHz. It comprised 2,800 separate ICs, but by the beginning of the 1970s the first microprocessors arrived – ICs that comprised all the components needed for a computer’s central processing unit. While the costs were still considerable – Intel’s 4-bit 4004 cost thousands of dollars – building a computer was far cheaper than ever before.

In the early 1970s, the falling price and increased availability of ICs made them increasingly available to electronic hobbyists, a small but significant group of people who used available components to build their own electronic devices such as calculators. Several magazines served the community, publishing projects that readers could undertake, discussing technological developments and, in some cases, helping to drive them forward. By 1974, Intel’s 8-bit 8008 microprocessor was within the reach of hobbyists, and the July issue of Radio-Electronics magazine published a project to build the 8008-powered Mark 8, ‘your personal minicomputer’.

Computer magazines have come a long way since 1974

The computer was fairly daunting, and only around 100 of the specially-produced circuit boards were sold, but the project inspired Popular Electronics magazine to take the idea further, commissioning Ed Roberts, the founder of Micro Instrumentation and Telemetry Systems (MITS), to design a computer in kit form that its readers could buy and build. MITS, established to supply rocketry and calculator kits, was heavily in debt, but what followed not only rescued it; it laid the foundations of widespread personal computing.

It’s hard to overstate the impact of the Altair 8800 and the events of 1975 in the history of personal computing. Launched as a project in the January 1975 issue of Popular Electronics, the Altair was available from MITS for $397 in kit form, or $498 preassembled – equivalent to roughly £179 and £224 then, or £1,100 and £1,400 in today’s money. It had an 8-bit Intel 8080 processor and 256 bytes of memory and, optionally, came with a version of the Basic programming language. At a time when only a tiny proportion of society had ever been directly exposed to computers, here was one that people could go out and buy for themselves. Journalist Art Salsburg, who wrote the accompanying editorial, proclaimed: “The home computer is here!”

EXPLOSION

While MITS had expected to sell 800 or so Altairs in total, they had taken 1,000 orders by the end of February 1975 and had delivered 2,500 computers by the end of May. MITS took on more employees and the Altair’s price went up. While the cheapest versions could be instructed in machine code, the true cost of a ‘Basic-speaking’ computer kit was nearly $1,900 (roughly £5,400 in today’s prices). Even so, in the context of the times the Altair 8800 was an incredible success in its own right, selling more than 10,000 units before MITS sold the design on. Its historical importance goes further. Its version of Basic was coded by Paul Allen and one William Henry Gates III (later known as Bill) and, though marketed as Altair BASIC, it was Microsoft’s founding product.

The influential Altair 8800 home computer

Bill Gates and Paul Allen had been friends since attending school together in Seattle, where Gates first learned to program in BASIC on a mainframe computer. Later, Gates and Allen were temporarily banned from another computer after they were caught exploiting bugs to get more time on the system. With two other students they would later offer to find and fix bugs in the system in return for more time on it. Gates’ colourful youth continued when, asked by his school to write a program that would schedule students’ classes, he added code to make sure his lessons contained mostly female students.