Four-Phase Systems

The idea behind Four-Phase Systems began when Boysel was designing MOS components at Fairchild Semiconductor in 1967. Boysel wrote a manifesto explaining how a computer could be built from a small number of MOS chips. Fairchild made Boysel head of a MOS design group, which he used to design parts satisfying the requirements of his putative computer. After doing this, Boysel left to start Four-Phase in October 1968, initially with two other engineers from his Fairchild group as well as others. Boysel was not sued by Fairchild, perhaps because of chaos caused by a change in Fairchild management at that time. When the company was incorporated in February 1969, he was joined by other engineers from the Fairchild group. Robert Noyce, co-founder of Intel, was an early board member.

Boysel arranged for chips to be fabricated by Cartesian, a wafer-processing company founded by another engineer from Fairchild. By spring of 1970, Four-Phase had an engineering-level system operating. Four-Phase showed its system at the Fall Joint Computer Conference in 1970. By June 1971, Four-Phase IV/70 computers were in use at four different customers, and by March 1973, they had shipped 347 systems to 131 customers. The company enjoyed a substantial level of success, having revenues of $178 million and 2,800 employees by 1979. As of 1979, their models included:

The IV/30 and IV/55 were intended for only one or two data entry/display stations, while the IV/40 and higher were intended for multiple high-volume data entry stations and independent data processing, and the IV/60 and higher could be made into small computer systems. In Europe, the IV/70 was sold as the Philips X1140-60 and the IV/90 was sold as the Philips P7000 series.

In 1982, Four-Phase was sold to Motorola for a $253 million stock exchange (equivalent to $844 million today). The former location of the business on N De Anza Blvd is now Apple's Infinite Loop campus.