 The first PET computers were sold primarily in Europe, where Commodore had also introduced the first wave of digital handheld calculators.As prices dropped and the market matured, the monochrome (green text on black screen) PET was at a disadvantage in the market when compared to machines like the Apple II and Atari 800, which offered color graphics and could be hooked to a television as an inexpensive display.Commodore responded with the VIC-20, and then the Commodore 64, which became the best-selling home computer of all time.