History time. It's kind of amusing to see these companies referred to as OG, when there were many generations of Silicon Valley startups before them. The real OG was probably Hewlett-Packard, founded in Palo Alto in 1939. Another key company was Shockley Semiconductor, founded in Mountain View in 1956. Eight key employees left Shockley in 1957 and formed Fairchild Semiconductor, gaining the name the "Traitorous Eight". Fairchild led to over 126 startups, sometimes called the Fairchildren, including AMD, Altera, LSI Logic, National Semiconductor, and SanDisk.
Two of the Traitorous Eight, Gordon Moore and Robert Noyce, left Fairchild in 1968, founding Intel in Mountain View. Later key Silicon Valley companies were Oracle (1977), Sun Microsystems (1982), and Cisco (1984). Although Apple started in 1976, it wasn't a dominant company until years later. Google (1998) and Facebook (2004) are relative newcomers.
Information on Fairchild's influence: https://computerhistory.org/blog/fairchild-and-the-fairchild...