1950: Simon Electromechanical Personal Computer
Although many believe that personal computer did not appear until the mid 1970's, there were a number of electromechanical devices prior to that aimed at hobbyists and capable of performing digital computations. The first of these was the Simon Mechanical Brain which was described by inventor Edmund Berkeley in his 1949 book "Giant Brains, or Machines That Think." Plans to build the Simon were published in a series of Radio-Electronics articles in 1950 and 1951. Development of electromechanical computers continued into the 1960's. The Minivac 601 was a model introduced in 1961 with its name derived from the Sperry Rand Univac computer.
It is true that personal computers capable of video output did not appear until the 1970's. The output of the electromechanical units like Simon consisted of an array of lights that illuminated on the front panel. The Simon had a memory capacity of six 2-bit words- a total of just 12 bits.