page_title: Mostek
section_title: Microprocessor second sourcing deals
hierarchical_section_title: Mostek / Microprocessor second sourcing deals
caption_attribution_description: English: CPU Mostek MK3880 (= Zilog Z80)
context_page_description: Mostek was an integrated circuit manufacturer, founded in 1969 by L. J. Sevin, Louay E. Sharif, Richard L. Petritz and other ex-employees of Texas Instruments. Initially their products were manufactured in Worcester, Massachusetts, however by 1974 most of its manufacturing was done in the Carrollton, Texas facility on Crosby Road. At its peak in the late 1970s, Mostek held an 85% market share of the dynamic random-access memory memory chip market worldwide, until being eclipsed by Japanese DRAM manufacturers who offered equivalent chips at lower prices by dumping memory on the market.
  In 1979, soon after its market peak, Mostek was purchased by United Technologies Corporation for $345M. In 1985, after several years of red ink and declining market share, UTC sold Mostek for $71M to the French electronics firm Thomson SA, later part of STMicroelectronics. Mostek's intellectual property portfolio, which included rights to the Intel x86 microprocessor family as well as many foundational patents in DRAM technology, provided a large windfall of royalty payments for STMicroelectronics in the 1990s.
context_section_description: With this foundation in calculator chips and high volume DRAM production, Mostek gained a reputation as a leading semiconductor "fabrication house" (fab) in the early 1970s. One of their more popular products was the Mostek 3870, which combined the two-chip Fairchild F8 (3850 + 3851) into a single chip, which they introduced in 1977. William H. Bradley designed a host of custom products based on the MK3870. Fairchild later licensed the 3870 back from Mostek. They also produced ROM chips on demand, as well as the chips powering the Hammond electronic organ.
  Mostek cut a deal with a startup, Zilog, in which Mostek provided fab resources to manufacture the Zilog microprocessors in return for second sourcing rights to the Zilog family. Mostek produced MK3880, the Zilog Z80 and a series of Z80 support chips, until Zilog built their own fab. The Z80 eventually became the most popular microcomputer family as it was used in millions of embedded devices as well as in many home computers and computers using the de facto standard CP/M operating system, such as the Osborne, Kaypro, and TRS-80 models.
  When Vin Prothro, President, and L. J. Sevin, Chairman of the Board, discovered that Zilog had modified the recipe for Z80 chips to keep the yields low, thereby buying Zilog time to build their own fabs, Mostek sought a new microprocessor partner. They negotiated a deal with Intel to gain second sourcing rights to the Intel 8086 microprocessor family and the future x86 designs. After Sevin left to become a venture capitalist (founding Compaq and many other companies), Prothro signed another pivotal deal with Motorola to gain the rights to the Motorola 68000 and VME computers.
  The Intel x86 microprocessors would go on to become the brains for the IBM PC, while the Motorola 68000 would become the heart of the Apple Macintosh line. Mostek had secured the rights to every microprocessor family that would be important for the next 25 years. However, Mostek chose not to aggressively follow-up its entry into microprocessors—instead maintaining its concentration on the highly competitive (and thereby unprofitable) DRAM business.
caption: Mostek MK3880P (Zilog Z80).
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