Apple was one of the most successful, but Steve Jobs didn't push out the Apple 1 until 76, Apple II came in 77. In 1975 the IBM 5100 Portable was out, but too expensive for most people. IBM threw the 'PC' on in 1981 when they introduced the IBM 5150 PC.
Way before this were other computers, back in 1955 there were the GENIACS and even a decade prior computers were used to crack codes during WWII.

This really has nothing to do with anything. I hate computers.