On December 19, 1974, MITS started selling kits for its computer, the Altair 8800. It was the first commercially successful personal computer, driven partially by its appearance on the cover of Popular Electronics magazine’s January 1975 issue. The kit cost $439, equivalent to $2885 in 2025 dollars.
Like a modern computer, only different
The Altair 8800 is the direct ancestor of the computer on your desk, but it had a number of differences from a modern computer. Most importantly, it lacked a built-in screen or keyboard. Instead, you connected a data terminal to it to get keyboard input and a display, much like you would with a minicomputer of the time. You could also program it and interact with it via its front-panel switches.
It did have expansion slots, a 100-pin bus that later became known as the S100 bus. A cottage industry providing expansion cards for the Altair 8800 soon sprung up, with some of the companies producing S100 cards eventually producing entire computers themselves.
And its most popular software title was a Microsoft product: Microsoft Basic, specifically. Microsoft Basic was a programming language, to allow Altair owners to create their own software. Microsoft announced Altair Basic January 2, 1975, and started shipping it later that summer.
When they called the Altair 8800 a kit, they meant it
But when they said it was a kit, they meant it. Assembling the Altair 8800 was nothing like assembling a modern computer. Nothing was pre-assembled. You pulled out the individual electronic components, soldered them to the included bare PCBs, then built the computer up from the resulting PCBs as you finished them. It wasn’t a project for the faint-hearted.
I only ever met one person who built up a 1970s computer kit. But when we talked about it more than 20 years after he’d built it, he was still proud of the accomplishment.
It was a laborious and slow process. There was the very real possibility you would never finish it. And if you did finish it, there was a very real possibility it would take more than a year, and something newer and better and cheaper would be available by the time you were done. That was the risk of 1970s personal computing.
Popularity
Nevertheless, the kits sold well and there was a waiting list. Bill Gates and Paul Allen couldn’t get one to write their Basic programming language on, so Paul Allen wrote an emulator that they ran on a DEC PDP-10 minicomputer to develop it. When Paul Allen flew to MITS headquarters to demo it, neither he nor Gates had seen it run on an actual Altair 8800. Ed Roberts needed to sell 200 Altairs to break even. They sold 1,000 units in February 1975 alone, but with fewer than 20 employees, they were only able to produce about 500 per month. MITS hired more than 70 employees in 1975 to try to keep up with demand. The legendary Homebrew Computer Club wasn’t exclusively an Altair club by a long shot, but the Altair was popular among its members.
By July 1975, other companies such as IMS were producing similar computers with varying degrees of compatibility.
In 1977, Ed Roberts sold MITS to Pertec Computer and retired from the computer industry. He moved to Georgia and started a software company so as to not violate his non-compete agreement with Pertec. In 1982, a medical school opened nearby. He enrolled, and graduated as an MD in 1986. He spent the rest of his career practicing medicine in small towns. Hospitalized and dying of pneumonia in March 2010, Bill Gates appeared unannounced to pay his last respects. Roberts died April 1, 2010.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.