While the Apple I was a successful machine for its day (selling about 200 kits - enough to keep Jobs and Woz going), the Apple II, designed and prototyped in 1976 but first sold in 1977, redefined success in the computer industry.
The apple II, pictured here in yet another old ad, was a complete box. It had everything the computer user of the day might need. Built in RAM, a software monitor and BASIC in ROM, video output and even a keyboard, case and power supply.
Complete systems like this would dominate Personal Computing forevermore. With the exception of a few die-hards, kits were also a thing of the past.
The Apple II also included support for some fairly advanced color graphics for the day which allowed programmers to add visuals to software in ways that other machines couldn't match. The most appealing use of this graphical capability was, of course, in game software. The appeal, although seemingly impractical, really helped the Apple make inroads into both the home and the classroom since many games were designed as educational tools.
The success of this machine with younger people eventually helped force its success with the older generations. Especially those who had learned on Apple's in their youth.
Perhaps the most intriguing aspect of the Apple II, however, was its "open architecture." Apple was not shy about sharing many aspects of their designs with the world and the world reacted with unprecedented support for the Apple computer line. Add-in cards and software were eventually available from hundreds of after market manufacturers, further cementing Apple's success.
Another 6502 based Micro introduced in 1977 was the Commodore PET (the Personal Electronic Transactor) which was introduced at the West Coast Computer Faire (as was the Apple ][.) This machine, like the Apple, was an all-in-one unit but it one-upped Apple by providing a cassette recorder built into the chassis, although this first model was the only PET to ever have that feature.
Commodore went on to expand and continue the PET line and, eventually, to release the Vic-20 and the Commodore-64 along with many variations on that line.
Several months after the introduction of the Apple ][ and Pet, and after turning down the Pet as an option for their stores, Radio Shack entered the computer business with the introduction of the TRS-80.
For MITS, 1977 brought about the beginning of the end. First, Microsoft broke off their licensing agreement with MITS for the BASIC language so they could sell their franchise product elsewhere. Shortly thereafter, MITS was sold to Pertec who somehow quickly destroyed the company.