Mostek

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Mostek Corporation

Mostek logo from the late 1970s until its acquisition by United Technologies
Industry	Semiconductors
Founded	1969; 56 years ago (1969) in Worcester, Massachusetts
Founder	L. J. Sevin Louay E. Sharif Richard L. Petritz
Defunct	1985 (1985)
Fate	Merged into STMicroelectronics

Mostek Corporation was a semiconductor integrated circuit manufacturer, founded in 1969 by L. J. Sevin, Louay E. Sharif, Richard L. Petritz and other ex-employees of Texas Instruments. At its peak in the late 1970s, Mostek held an 85% market share of the dynamic random-access memory (DRAM) memory chip market worldwide, until being eclipsed by lower-priced Japanese DRAM manufacturers who were accused of dumping memory on the market.^[1]

In 1979, soon after its market peak, Mostek was purchased by

Mostek's first contract was from

Mostek had been working with Sprague Electric to develop the ion implantation process^[2] which provided much better control of doping profiles, especially in lowering enhancement-mode transistor threshold voltage and providing depletion-load transistors. Using ion implantation, Mostek became an early leader in MOS manufacturing technology, while their competition was still mostly using the older bipolar technology. The resulting increased speed and lower cost of the MK4006 memory chip made it the runaway favorite to IBM and other mainframe and minicomputer manufacturers (cf. BUNCH, Digital Equipment Corporation).

In 1970 Busicom, a Japanese adding machine manufacturer, approached Intel and Mostek with a proposal to introduce a new electronic calculator line. Intel responded first, providing them with the Intel 4004, which they used in a line of desktop calculators. Mostek's device took longer to develop but was the world's first single chip calculator, the MK6010, used for the Busicom LE-120A which went on the market in 1971 and was the smallest calculator available for some time.^[3] Hewlett-Packard also contracted with Mostek for design and production of chips for their HP-35 and HP-45 calculators.^[4]

Mostek co-founder Robert Proebsting invented

Mostek's DRAM legacy is exemplified in the MK4116, MK4164 and MK41256. "By four" DRAM was a simple adaptation of the MK4116/MK4164/MK41256 technology, utilizing a larger package to accommodate the additional data bits and multiplexing the data in/out pins as well; the basic *RAS, *CAS, *WRITE and multiplexed address bus concept was retained intact.

Mostek enjoyed many years of mastery of the international market for telecommunications products. Their product line included telephone tone and pulse dialers,

Bradley designed all of the custom products based on the single-chip-calculator platform, as well as the code for the wristwatch chips produced by Mostek for Bulova and other customers. For a short while, Paluck headed a joint venture called Mostek Hong Kong, a collaboration with Bulova for the production of high-end wristwatches based on Mostek designs. Bradley was an employee of that joint venture. Paluck left Mostek to work with Sevin Rosen Funds and Convex Computer. As Mostek's focus was shifted to its DRAM products, the industrial and telecommunications products were ignored and their market share vanished.

With this foundation in calculator chips and high volume DRAM production, Mostek gained a reputation as a leading semiconductor "fabrication house" (

In 1974 Mostek introduced the MK5065, an 8-bit PMOS microprocessor, with 51 instructions whose execution times range from 3 to 16 μs. Architectural features included multiple nested indirect addressing and three register sets (each consisting of an accumulator, a program counter and a carry/link bit) which could be used for interrupt processing or for subroutines.^[7][8][9] Bill Mensch was one of the engineers who had actually designed the 5065 at Motorola for Olivetti.^{[citation needed]}

A more popular product was the MK3870, which combined the two-chip Fairchild F8 (3850 + 3851) into a single chip,^[10] introduced in 1977. William Bradley designed a host of custom products based on the 3870. Fairchild later licensed the 3870 back from Mostek. Mostek also produced ROM chips on demand, as well as the chips powering the Hammond electronic organ.

Mostek MK3880P (Zilog Z80)

– metal layer

– silicon only

Mostek MK3880 (Zilog Z80) die

During the introduction of the Z80, Zilog needed a production partner while they got their own fabs set up. They first signed a production agreement with Synertek, but the company later demanded they sign a second source deal, allowing Synertek to produce and sell the design on their own. Zilog refused, so the agreement was broken. Zilog then selected Mostek as the only other company capable of building a +5V device (as opposed to +5 and +12).^[11] Mostek had developed advanced layout methods which were applied to the Z80, resulting in the device being shrunk by 20%.^[12] Mostek was able to sign a second source deal for what it called the MK3880.^[13] The Z80 eventually became the most popular microcomputer family, and 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.^[a]

Mostek sought new microprocessor partners and negotiated deals with Intel to gain second sourcing rights to the

Mostek was bought by United Technologies (UTC) in 1979 for US$345M to prevent an unfriendly takeover from Gould at the 10th anniversary of the company's founding, when a large block of stock options controlled by Sprague Electric became vested. The leadership UTC chose for its semiconductor division did not appreciate the up-front investment required or the long time for ROI.^[14]

UTC at first invested hundreds of millions to expand Mostek, then hundreds of millions more trying to keep the company going during the various semiconductor and videogame crashes of the early 1980s. UTC sacrificed Mostek's leadership position in some markets, focusing instead on the highly competitive (and eventually unprofitable) DRAM business.

Unfortunately the DRAM marketplace was the beachhead where

Mostek's 256K DRAM had been delayed by a then-ambitious double-layer metallization design. In 1985, when the price for 64Ks had collapsed and 256K prices were already under $10, Mostek's 256K device was still not ready for volume production, and the company suffered heavy losses. Eventually, on 17 October 1985, UTC gave up, closed Mostek completely, and days later sold it to Thomson-CSF, a French Government electronics company, for a mere $71 million.^[16] By 1986, all United States chip makers, with the exception of Texas Instruments, Micron Technology, Motorola and IBM had stopped making DRAM.^[17] As of 1990, they represented less than 10% of the world's supply. ^[18]

UTC closed Mostek completely in 1985 and sold it for US$71M to the French electronics firm Thomson-CSF. Thomson called back only about 20% of the workforce in an attempt to return Mostek to profitability. Thomson's Mostek operations continued under the name TCMC (Thomson Components - Mostek Corp).

In 1987 Thomson spun-off and merged its semiconductor operations, including Mostek, with the Italian

Micron Technology was a very successful spinoff founded by a handful of Mostek employees, including Ward Parkinson, Dennis Wilson, and Doug Pitman.^{[citation needed]}

Sevin Rosen Funds co-founded by LJ Sevin funded Compaq Computers, Cyrix, Convex Computers and more.^{[citation needed]}

Bob Paluck started Convex Computers in 1982. Vin Prothro started Dallas Semiconductor in ca 1984. Mike Callahan started Crystal Semiconductor in ca 1979. Charles Johnson started SRX in ca 1981.

As a full IDM (Integrated Device Manufacturer) Mostek had a full array of divisions including Design, Photomask, Wafer Fab, Test, Assembly/Packaging, Product Engineering, Quality/Reliability, Sales/Marketing. For nearly all of its existence Bob Palmer was Senior Vice-President over all these divisions.

Jim Piker founded and managed Mostek's in-house Photomask operations. The photomask step and repeat techniques eventually were copied for wafer fabrication ca 1968.

Mostek's first wafer fab was provided by Sprague at its plant in Worcester, Ma near Boston. In ca 1973, Mary Ann Potter founded and managed Fab1 at 1215 Crosby Rd in Carrollton, Tx, a NW suburb of Dallas, in a converted warehouse around the corner from Mostek's corporate office on Upfield St.

Also at the main Crosby Rd site: a small R&D fab was started ca 1974 which eventually became Fab3, Fab2 was founded ca 1975, Fab4 (in a new building) ca 1978, Fab5 in 1979, Fab6 ca 1984, and a Colorado Springs Fab ca 1984.

Testing and Burn-In were located at the main site on Crosby Rd.

Mostek's main Packaging operations were in Panang, Malaysia.

• "Oral History of Charles Phipps", Computer History Museum, May 28, 2009, Interviewer: Rosemary Remacle.
• "Mostek Prospectus" March 17, 1972