April 16, 1977
On the same day at the first annual West Coast Computer Faire, both the Apple II and Commodore PET 2001 personal computers are introduced. Ironically, Commodore had previously rejected purchasing the Apple II from Steve Jobs and Steve Wozniak, deciding to build their own computers. Both computers used the same processor, the MOS 6502, but the companies had two different design strategies and it showed on this day. Apple wanted to build computers with more features at a higher price point. Commodore wanted to sell less feature-filled computers at a lower price point. The Apple II had color, graphics, and sound selling for $1298. The Commodore PET only had a monochrome display and was priced at $795.
Note, it was very difficult finding a picture with both an original Apple II (not IIe) and Commodore PET 2001. I could only find this picture that also includes the TRS-80, another PC introduced later in 1977.