In 1975 Popular Electronics Magazine, responding to an article from a competing magazine, Radio Electronics, published an article about a new "minicomputer" kit. This article, along with an advertisement in Scientific American launched the PC revolution with the MITS Altair 8800 computer.
Those familiar with the Altair computers probably won't recognize what's on the cover. This was a quick and dirty mock-up created for the photo shoot when the one and only prototype was lost in transit to the Popular Electronics offices.
The Altair 8800 was built around the Intel 8080 microprocessor which was, arguably, the first viable chip for the purpose. As legend has it, this machine was named after the planet that the Star Ship Enterprise was visiting the evening they needed to come up with a name.
In 1975 you could spend $397 to buy an Altair kit that enabled you to build the Altair 8800 computer. For $439 you could get the computer pre-built, but you would have to wait months for delivery.
The introduction of the Altair 8800 set in motion a chain of events that defined the landscape of Personal Computing as we know it today.
Microsoft was formed in response to this new innovation.
Over time many existing companies began to realize the viability of smaller computers geared towards individual users while dozens of other companies took advantage of the void to introduce their own version of the right answer.
1975 also saw the introduction of Creative Computing magazine (actually founded in late 1974) as well as Byte Magazine. The first Computer stores, now as common as fast-food outlets, were opened late in 1975 with Arrowhead Computer Co. opening "The Computer Store" in Los Angeles in July and the Byte Shop opening in the Bay Area shortly thereafter.
Several computer hobbyist clubs were founded that acted as incubators for the Personal Computer revolution. The most significant of these clubs were the "Homebrew Computer Club" founded in the heart of silicon valley and the Southern California Computer Society founded in Los Angeles.
Although Intel had early control of the microprocessor world other companies quickly began entering the field. In 1975 MOS Technology introduced the 6502 microprocessor for an unheard of $25 per chip, drastically undercutting Intel's prices for the 8080. The 6502 would eventually be used in a wide variety of computers including those from Apple and Commodore.