Mostek

Mostek Corporation

Industry	Semiconductor industry
Founded	1969
Founder	L. J. Sevin, Louay E. Sharif, Richard L. Petritz, and other former Texas Instruments personnel
Defunct	1985
Fate	Acquired by United Technologies Corporation in 1979; operations ceased in 1985; sold to Thomson-CSF and merged into STMicroelectronics
Successor	STMicroelectronics (via Thomson-CSF)
Headquarters	Carrollton, Texas , United States
Area served	Global
Key people	Robert Proebsting, Paul Schroeder, William Bradley, Bob Paluck, Dave Seeler, Mike Callahan, Charles Johnson, Robert C. Jones, Bob Banks, Ted Lewis, Darin Kincaid, John Crago, Randall Hopkins, Henry Wasik
Products	Dynamic random-access memory (DRAM) chips, calculator chips, microprocessors (MK5065, MK3870, MK3880), telecommunications components (telephone tone and pulse dialers, touchtone decoders), watch timing circuits, CODECs
Owner	United Technologies Corporation (1979–1985), then Thomson-CSF
Parent	United Technologies Corporation (1979–1985)

Mostek Corporation was established in 1969 by L. J. Sevin, Louay E. Sharif, Richard L. Petritz, along with other former Texas Instruments personnel, specializing in semiconductor integrated circuits. By the late 1970s, Mostek had secured an 85% share of the global dynamic random-access memory (DRAM) chip market, before Japanese manufacturers offering lower-priced DRAMs—allegedly through dumping—surpassed them.

In 1979, soon after achieving market leadership, United Technologies Corporation (UTC) acquired Mostek for $345 million. Following several years marked by financial deficits and shrinking market presence, UTC ceased Mostek’s operations in 1985 and sold the company to Thomson-CSF, a French electronics enterprise, for $71 million. Thomson-CSF eventually merged Mostek into STMicroelectronics.

Early Products

Mostek’s first contract involved designing a $400 circuit for Burroughs Corporation. Initial production was handled in Worcester, Massachusetts by Sprague Electric; however, by 1974, the company centralized manufacturing at its headquarters in Carrollton, Texas. Their debut product was the MK1001 barrel shifter chip based on aluminum-gate PMOS technology, succeeded by the MK4006 1K DRAM developed by Vern McKinney and fabricated in Carrollton.

Partnering with Sprague Electric to advance ion implantation techniques enhanced doping accuracy and transistor efficiency. This breakthrough allowed Mostek to excel in MOS fabrication while many competitors continued using bipolar processes. The resulting improvements boosted speed and lowered manufacturing expenses, making the MK4006 highly favored among mainframe and minicomputer producers such as IBM and Digital Equipment Corporation.

In 1970, Busicom—a Japanese adding machine manufacturer—approached both Intel and Mostek for electronic calculator chips. Although Intel introduced the Intel 4004 first, Mostek created the world’s inaugural single-chip calculator, the MK6010, which powered Busicom’s LE-120A calculator released in 1971. This innovation enabled the production of the smallest calculators available at that period. Hewlett-Packard also contracted Mostek to supply chips for their HP-35 and HP-45 calculator models.

World leader in DRAM

Mostek co-founder Robert Proebsting introduced DRAM address multiplexing with the MK4096 4K x 1 bit DRAM in 1973. This advancement minimized costs and reduced circuit board space by fitting a 4K DRAM into a compact 16-pin package instead of the bulkier 22-pin versions used by rivals. Proebsting’s design facilitated scaling future DRAM capacities using fewer pins, which decreased per-pin expenses and silicon usage—key factors influencing chip cost-efficiency.

The MK4096 utilized an NMOS aluminum-gate process enhanced with a polysilicon interconnect layer known as the SPIN process. Despite initial doubts from competitors, this chip demonstrated strong performance across diverse computer memory applications.

In 1976, Mostek released the silicon-gate MK4027 followed by the MK4116 16K double-poly silicon-gate DRAM in 1977, engineered by Paul Schroeder and Robert Proebsting. The MK4116 captured over 75% of the worldwide DRAM market, cementing Mostek’s dominance. Both models were extensively copied internationally, highlighting their substantial impact on the industry.

The move to 64K DRAM technology required transitioning from operating voltages of 12V and ±5V to a single 5V supply to free pins for addressing purposes. Unlike competitors who merely downsized prior designs, Mostek undertook a comprehensive redesign incorporating advanced features such as controlled pre-charge current. Although this caused a delayed market introduction, it positioned Mostek advantageously for future expansion.

Mostek’s influence persisted with subsequent models including the MK4116, MK4164, and MK41256. The "by four" DRAM innovation expanded on this foundation by employing larger packages and multiplexed data pins while maintaining essential signals (*RAS, *CAS, *WRITE) alongside a multiplexed address bus—illustrating Mostek’s ongoing innovation and leadership within the semiconductor sector.

Global pioneer in telecommunications components

Mostek built a significant global footprint in telecommunications components, supplying products such as telephone tone and pulse dialers, touchtone decoders, counters, and top-octave generators utilized by manufacturers like Hammond and Baldwin. Their portfolio also included CODECs, watch timing circuits, and a variety of custom-designed solutions. Employing aluminium-gate PMOS technology initially, followed by aluminium-gate CMOS processes, these offerings provided vital revenue streams during periods of fierce competition in the DRAM sector and broader semiconductor industry challenges. A significant setback occurred in 1975 when a fire incapacitated the wafer fabrication facility for several months, prompting the transfer of essential production to Silicon Valley’s Synertek.

Leadership within the Telecommunications and Industrial Products Division featured key figures such as Bob Paluck (director), Dave Seeler, Mike Callahan, Charles Johnson, William Bradley, Robert C. Jones, Bob Banks, Ted Lewis, Darin Kincaid, and William Cummings. The marketing efforts for telecom products were overseen by John Crago, Randall Hopkins, and Henry Wasik. Following United Technologies’ acquisition of Mostek, Lewis and Bradley were recognized as principal personnel.

William Bradley was instrumental in designing custom products built on a single-chip calculator architecture and programming wristwatch integrated circuits for clients including Bulova. Paluck briefly managed Mostek Hong Kong, a collaborative venture with Bulova focused on manufacturing premium wristwatches based on Mostek’s designs. Subsequently, Paluck transitioned to roles at Sevin Rosen Funds and Convex Computer. As Mostek increasingly prioritized DRAM product lines, its industrial and telecommunications segments experienced declining market penetration.

Microprocessor second-source agreements

Capitalizing on its expertise in calculator chip technology and high-volume DRAM manufacturing capabilities, Mostek emerged as a prominent semiconductor fabrication facility (fab) during the early 1970s.

MK5065

In 1974, Mostek introduced the MK5065, an 8-bit PMOS microprocessor executing 51 instructions with cycle times ranging from 3 to 16 microseconds. Its design incorporated multiple levels of nested indirect addressing along with three distinct register sets—each containing an accumulator, program counter, and carry/link bit—to facilitate interrupt processing or subroutine execution. Notably, engineer Bill Mensch, who originally designed the 5065 at Motorola for Olivetti, contributed significantly to its development.

MK3870

Released in 1977, the MK3870 integrated the functionality of the two-chip Fairchild F8 system (3850 + 3851) into a single semiconductor device. William Bradley developed numerous custom solutions based on this chip. Fairchild subsequently licensed this integrated device back from Mostek. Furthermore, Mostek manufactured ROM chips on demand as well as components employed in the Hammond electronic organ.

MK3880

When Zilog sought a manufacturing partner for the Z80 microprocessor, it initially engaged Synertek. However, after Synertek requested a second source agreement that Zilog declined to grant, Mostek was chosen as the exclusive alternative capable of producing a +5V-compatible version. Utilizing advanced layout techniques, Mostek achieved a 20% reduction in the Z80’s die size and secured a second-source contract for their variant known as the MK3880. The Z80 microprocessor became highly popular in embedded applications and home computers running CP/M, including models such as the Osborne, Kaypro, and TRS-80.

Additional Partnerships

Mostek sought collaborative agreements to obtain secondary sourcing rights for crucial microprocessors, including Intel’s Intel 8086 and subsequent x86 architectures, as well as Motorola’s Motorola 68000 and VME systems. These alliances strategically placed Mostek across all principal microprocessor platforms that would dominate the following quarter-century—Intel’s x86 architecture powering the IBM PC, and Motorola’s 68000 series underpinning the Macintosh. Nevertheless, Mostek concentrated primarily on its DRAM operations rather than aggressively expanding its footprint in the microprocessor sector.

Challenges Amid Rising Asian Competition

In 1979, United Technologies (UTC) acquired Mostek for $345 million to thwart a potential hostile takeover by Gould, triggered by a substantial vesting of stock options. The leadership appointed by UTC to oversee its semiconductor division lacked a clear understanding of the significant upfront capital requirements and the extended timeframe needed for returns on investment.

Initially, UTC infused hundreds of millions of dollars to grow Mostek and later provided additional financial support to sustain it through the semiconductor downturn and the video game industry collapse in the early 1980s. However, UTC eventually redirected its focus away from Mostek's core markets towards the fiercely competitive and ultimately unprofitable DRAM segment.

The DRAM market became the entry point for Japanese companies to establish dominance over the global semiconductor industry. By 1985, Japanese manufacturers controlled more than 60% of 64K DRAM production—the most widely used memory chips in computing devices. U.S. semiconductor firms, including Micron (a Mostek offshoot), accused Japanese competitors of engaging in export dumping practices aimed at eliminating American rivals. As a result, prices for 64K DRAM chips plummeted from $3.50 to as low as 35 cents within an 18-month period, severely undermining U.S. producers. Although the U.S. Commerce Department ruled in favor of these complaints on December 4, 1985, this decision came too late to rescue Mostek.

Mostek's introduction of its 256K DRAM was hampered by an ambitious double-layer metallization design. By 1985, with prices for 64K chips collapsed and 256K chips selling below $10, Mostek’s new product was not yet ready for mass production, leading to significant financial losses. On October 17, 1985, UTC ceased Mostek’s operations and sold the company shortly thereafter to Thomson-CSF, a French government-owned electronics firm, for $71 million. UTC retained one fabrication facility in Colorado Springs under UTMicroElectronics Center.

By 1986, only Texas Instruments, Micron Technology, Motorola, and IBM continued U.S.-based DRAM manufacturing. By 1990, American companies accounted for less than 10% of worldwide DRAM output.

Subsequent Developments

After closing Mostek in 1985, UTC sold it to French electronics corporation Thomson-CSF, which kept approximately one-fifth of the workforce to restore profitability. Thomson operated the business under the name TCMC (Thomson Components - Mostek Corp).

In 1987, Thomson merged its semiconductor assets—including Mostek—with Italian firm SGS-ATES to establish STMicroelectronics, headquartered in Geneva, Switzerland. Initially called SGS-Thomson, the company adopted its current name in 1998 after Thomson divested its shares. Between 1987 and 1993, STM generated $450 million in licensing revenue from Mostek’s valuable DRAM patent portfolio.

STM continued operations at the Carrollton facility for several years and maintained a modest presence in Coppell, Texas. Former employees of Mostek convene annually under the group name "MostekLives!".

Spinoffs

In 1988, Jerry Rogers established Cyrix to capitalize on Mostek’s second-source agreement for 80x86 processors; however, this partnership was ultimately terminated due to Intel's legal actions, which led to the rebranding of the 80586 as the Pentium.

Among the most successful companies spun off from Mostek is Micron Technology, founded by former employees such as Ward Parkinson, Dennis Wilson, and Doug Pitman.

Sevin Rosen Funds, co-founded by LJ Sevin, provided venture capital to emerging companies including Compaq Computers, Cyrix, and Convex Computers.

Additional significant spinoffs comprise Convex Computers (established by Bob Paluck in 1982), Dallas Semiconductor (founded by Vin Prothro around 1984), Crystal Semiconductor (initiated by Mike Callahan circa 1979), and SRX (created by Charles Johnson around 1981).

Mostek Manufacturing

Operating as a fully integrated device manufacturer (IDM), Mostek maintained departments across Design, Photomask production, Wafer Fabrication, Testing, Assembly/Packaging, Product Engineering, Quality and Reliability Assurance, as well as Sales and Marketing. Bob Palmer held the position of Senior Vice-President overseeing these areas for the majority of the company's duration.

Photomask

Jim Piker was responsible for founding and directing Mostek’s internal Photomask division. The step-and-repeat photomask technology developed under his leadership became a standard method adopted industry-wide for wafer fabrication starting around 1968.

Wafer Fabrication

Mostek’s original wafer fabrication facility operated within Sprague’s plant located in Worcester, Massachusetts. In approximately 1973, Mary Ann Potter launched Fab1 at 1215 Crosby Rd in Carrollton, Texas—close to Mostek’s headquarters—utilizing a repurposed warehouse space.

Subsequently, additional fabrication plants were introduced: a small R&D fab established circa 1974 later expanded into Fab3; Fab2 commenced operations around 1975; Fab4 was inaugurated in a new facility near 1978; Fab5 began in 1979; and both Fab6 and a site in Colorado Springs were initiated around 1984.

Test

The primary testing and burn-in processes took place at Mostek’s main facility on Crosby Road.

Assembly/Packaging

Mostek’s chief packaging operations were based in Penang, Malaysia.

References

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

External links

• MK4116 DRAM (Smithsonian Chip Collection)
• Mostek (Antique Tech)