Editing MOS Technology (section)

==History==
[[File:MOS Technology ad April 26 1973.jpg|thumb|A 1973 MOS Technology advertisement highlighting their custom integrated circuit capabilities]]

Three former [[General Instrument]] executives, John Paivinen, Mort Jaffe and Don McLaughlin, formed MOS Technology in Valley Forge, Pennsylvania in 1969. The [[Allen-Bradley|Allen-Bradley Company]] was looking to provide a second source for electronic calculators and their chips designed by [[Texas Instruments]] (TI). In 1970 Allen-Bradley acquired a majority interest in MOS Technology. 

In the early 1970s, TI decided to release their own line of calculators, instead of selling just the chips inside them, and introduced them at a price that was lower than the price of the chipset alone. Many early chip companies were reliant on sales of calculator chips and were wiped out in the aftermath; those that survived did so by finding other chips to produce. MOS became a supplier to [[Atari]], producing a custom single-chip ''[[Pong]]'' system.

Things changed dramatically in 1975. Several of the designers of the [[Motorola 6800]] left Motorola shortly after its release, after management told them to stop working on a low-cost version of the design. At the time there was no such thing as a [[pure-play semiconductor foundry]], so they had to join a chip-building company to produce their new CPU. MOS was a small firm with good credentials in the right area, the east coast of the US. The team of four design engineers was headed by [[Chuck Peddle]] and included [[Bill Mensch]]. At MOS they set about building a new [[CPU]] that would outperform the 6800 while being similar to it in purpose and much less expensive. The resulting [[MOS Technology 6501|6501]] design was somewhat similar to the 6800, but by using several design simplifications, the 6501 would be up to four times faster.

===Mask fixing===
Previous CPU designs, like the 6800, were produced using a device known as a [[Contact lithography|contact aligner]]. This was essentially a complex [[photocopier]], which optically reproduced a CPU design, or "mask", on the surface of the silicon chip. The name "contact" referred to the fact that the mask was placed directly on the surface of the chip, which had the significant disadvantage that it sometimes pulled away materials from the chip, which were then copied to subsequent chips. This caused the mask to become useless after about a dozen copies, and resulted in the vast majority of chips having fatal flaws; for a complex chip like the 6800, only about 10% of the chips would work once the masking process was complete.<ref name=Mensch/>

In 1974 [[Perkin-Elmer]] publicly introduced the [[Micralign]] system, the first projection scanner. Instead of placing the mask on the surface of the chip, it held it far from the surface and used highly accurate optics to project the image. Masks now lasted for thousands of copies instead of tens, and the flaw rate of the chips inverted so that perhaps 70% of the chips produced would work. The result was a similar inversion in pricing. The 6800 sold in small lots for {{US$|long=no|295}}; with no other changes than using a [[Micralign]], the same design could sell for {{US$|long=no|42}}.<ref name=Mensch/>

The change to the Micralign revealed a further advantage. Previously the masks were mass-produced by photography companies like [[Kodak]], who would make tens of thousands of copies of a master mask, or "[[reticle]]", and ship the masks to the aligners by the truckload. This meant that if a flaw was found in the design, it would cost a significant amount of money to fix it, as all the older masks would have to be thrown out. In contrast, with Micralign there was only one mask per aligner, so there was no inherent cost in replacing the mask if need be, although the cost, and especially time, of producing these master masks was considerable.<ref name=Mensch/>

MOS developed the ability to "fix" its masks after they had been produced.<ref name=Mensch>{{Cite web|url=https://archive.computerhistory.org/resources/access/text/2015/06/102739969-05-01-acc.pdf |title=Oral History of William David "Bill" Mensch, Jr. |last=Mensch|first=Bill|date=10 November 2014 |website=Computer History Museum |page=18}}</ref> This meant that as flaws in the design were discovered, the masks could be removed from the aligners, fixed, and put back in. This allowed them to rapidly drive out flaws in the original masks.

The company's production lines typically reversed the numbers others were achieving; even the early runs of a new CPU design&mdash;what would become the 6502&mdash;were achieving a success rate of 70 percent or better. This meant that not only were its designs faster, but they also cost much less as well.

===6502 family===
{{main|MOS Technology 6502}}
When the 6501 was announced, Motorola launched a lawsuit almost immediately. Although the 6501 [[instruction set]] was not compatible with the 6800, it could nevertheless be plugged into existing [[motherboard]] designs because it had the same functional pin arrangement and [[IC package]] footprint. That was enough to allow Motorola to sue. Allen-Bradley sold back its shares to the founders, sales of the 6501 basically stopped, and the lawsuit would drag on for many years before MOS was eventually forced to pay {{US$|200000}} in fines.

In the meantime MOS had started selling the [[MOS Technology 6502|6502]], a chip capable of operating at {{val|1|ul=MHz}} in September 1975 for a mere {{US$|25}}. It was nearly identical to the 6501, with only a few minor differences: an added on-chip clock oscillator, a different functional pinout arrangement, generation of the SYNC signal (supporting single-instruction stepping), and removal of data bus enablement control signals (DBE and BA, with the former directly connected to the phase 2 clock instead).<ref>{{Cite web|url=http://www.6502.org/documents/books/mcs6500_family_hardware_manual.pdf|title=MOS MCS6500 Microcomputer Family Hardware Manual (Publication Number 6500-10A), January 1976, p. 41.}}</ref>  It outperformed the more-complex 6800 and [[Intel 8080]], but cost much less and was easier to work with. Although it did not have the 6501's advantage of being able to be used in place of the Motorola 6800 in existing hardware, it was so inexpensive that it quickly became more popular than the 6800, making that a moot point.

[[Image:MOS Technologies large.jpg|thumb|Image of the circuit board of a [[Commodore 64]] showing some important MOS Technology circuits: the [[MOS Technology 6510|6510 CPU]] (long chip, lower left) and the [[MOS Technology SID|6581 SID]] (right). The production week/year (WWYY) of each chip is given below its name.]]

The 6502 was so cheap that many people believed it was a scam when MOS first showed it at a 1975 trade show. They were not aware of MOS's masking techniques and when they calculated the price per chip at the current industry yield rates, it did not add up. But any hesitation to buy it evaporated when both Motorola and Intel dropped the prices on their own designs from {{val|p=$|179}} to {{val|p=$|69}} at the same show in order to compete. Their moves legitimized the 6502, and by the show's end, the wooden barrel full of samples was empty.{{citation needed|date=October 2012}}

The 6502 would quickly go on to be one of the most popular chips of its day. A number of companies licensed the 650x line from MOS, including [[Rockwell International]], [[GTE]], [[Synertek]], and [[Western Design Center|Western Design Center (WDC)]].

A number of different versions of the basic CPU, known as the 6503 through 6507, were offered in 28-pin packages for lower cost. The various models removed signal or address pins. Far and away the most popular of these was the [[MOS Technology 6507|6507]], which was used in the [[Atari 2600]] and Atari disk drives. The 6504 was sometimes used in printers. MOS also released a series of similar CPUs using external clocks, which added a "1" to the name in the third digit, as the 6512 through 6515. These were useful in systems where the clock support was already being provided on the motherboard by some other source. The final addition was the "crossover" [[6510]], used in the [[Commodore 64]], with additional I/O ports.

===Commodore Semiconductor Group===
However successful the 6502 was, the company itself was having problems. At about the same time the 6502 was being released, MOS's entire calculator [[Integrated circuit|IC]] market collapsed, and its prior existing products stopped shipping. Soon they were in serious financial trouble. Another company, [[Commodore Business Machines]] (CBM), had invested heavily in the calculator market and was also nearly wiped out by [[Texas Instruments|TI]]'s entry into the market. A fresh injection of capital saved CBM, and allowed it to invest in company suppliers in order to help ensure their [[Integrated circuit|IC]] supply would not be upset in this fashion again. Among the several companies were [[LED]] display manufacturers, power controllers, and suppliers of the driver chips, including MOS.

In late 1976, CBM, publicly traded on the [[NYSE]] with a [[market capitalization]] around {{US$|60 million}}, purchased MOS (whose market cap was around {{US$|12 million}}) in an all-stock deal. Holders of MOS received a 9.4 percent equity stake in CBM<ref>{{cite web|title=MOS – The Rise of MOS Technology & The 6502
|publication-date=2006-01-18<!-- originally written by Ian Matthews of commodore.ca in 2003-02-15 -->
|date=March 2015
|access-date=2016-05-10
|url=http://www.commodore.ca/commodore-history/the-rise-of-mos-technology-the-6502/
|quote=MOS Technology is privately owned and valued at around $12 million.<!--original source: September 1976 edition of New Scientist-->
}}</ref><ref>{{Cite magazine|url=https://books.google.com/books?id=xUAV0VcszIQC&pg=PA541,|title=Calculator maker integrates downwards |magazine=New Scientist|date=September 9, 1976 |page=541 |volume=71 |issue=1071|publisher=Reed Business Information|via=Google Books}}</ref><ref>"Commodore Buys MOS Technology", ''New Scientist'', September 1976</ref> on the condition that Chuck Peddle would join Commodore as chief engineer. The deal went through, and while the firm basically became Commodore's production arm, they continued using the name MOS for some time so that manuals would not have to be reprinted. After a while MOS became the '''Commodore Semiconductor Group (CSG)'''. Despite being renamed to CSG, all chips produced were still stamped with the old "MOS" logo until week 22/23 of 1989.<ref>Images of chips with week 22 and week 23 date codes.{{better source needed|{{subst:DATE}}|date=August 2024}}</ref>

MOS had previously designed a simple computer kit called the [[KIM-1]], primarily to "show off" the 6502 chip. At Commodore, Peddle convinced the owner, [[Jack Tramiel]], that calculators were a dead end, and that home computers would soon be huge.

However, the original design group appeared to be even less interested in working for Jack Tramiel than it had for Motorola, and the team quickly started breaking up. One result was that the newly completed [[MOS Technology 6522|6522 (VIA)]] chip was left undocumented for years.

[[Bill Mensch]] left MOS even before the Commodore takeover, and moved home to Arizona. After a short stint consulting for a local company called ICE, he set up the [[Western Design Center|Western Design Center (WDC)]] in 1978. As a licensee of the 6502 line, their first products were bug-fixed, power-efficient [[CMOS]] versions of the 6502 (the [[65C02]], both as a separate chip and embedded inside a [[microcontroller]] called the 65C150). But then they expanded the line greatly with the introduction of the [[65816]], a fairly straightforward [[16-bit]] upgrade of the original 65C02 that could also run in [[8-bit]] mode for compatibility. Since then WDC moved much of the original MOS catalog to CMOS, and the 6502 continued to be a popular CPU for the [[embedded system]]s market, like medical equipment and car dashboard controllers.

===GMT Microelectronics===
After Commodore's [[bankruptcy]] in 1994, Commodore Semiconductor Group, MOS's successor, was bought by its former management for about {{US$|long=no|4.3 million}}, plus an additional {{US$|long=no|1 million}} to cover miscellaneous expenses including a [[United States Environmental Protection Agency]] (EPA) license. Dennis Peasenell became CEO. In December 1994, the EPA entered into a Prospective Purchase Agreement (limiting the company's liability in exchange for sharing the costs of cleanup) with GMT Microelectronics. In 1994, the company, operating under the name '''GMT Microelectronics''' (''Great Mixed-signal Technologies''), reopened MOS Technology's original, circa-1970 [[1 µm process|one-micrometre]] process fab ([[semiconductor fabrication plant]]) in [[Audubon, Pennsylvania|Audubon]], [[Montgomery County, Pennsylvania|Montgomery County]], Pennsylvania that Commodore had closed in 1993.<ref name="CSG EPA">{{cite web |url=https://semspub.epa.gov/work/03/2218465.pdf |title=THIRD FIVE-YEAR REVIEW REPORT For Commodore Semiconductor Group Superfund Site |publisher=United States Environmental Protection Agency Region III |url-status=dead |date=August 2015 |archive-url=https://web.archive.org/web/20200521044458/https://semspub.epa.gov/work/03/2218465.pdf |archive-date=2020-05-21}}</ref>

The plant had been on the EPA's National Priorities List of [[hazardous waste]] sites since October 4, 1989.<ref>{{cite web |url=https://www.karlstechnology.com/commodore/commodore-superfund-site.html |title=Commodore Computers Superfund Site Information |publisher=Environmental Protection Agency |date=April 2004|access-date=May 23, 2019}}</ref><ref>{{Cite web|date=August 2002|title=Commodore Semiconductor Group|url=https://semspub.epa.gov/work/HQ/182397.pdf|access-date=2020-08-11|website=epa.org}}</ref> This was due to a 1978 leak of [[trichloroethylene]] (TCE) from an underground 250-gallon concrete storage tank used by [[Commodore Business Machines]] in the semiconductor cleaning process.<ref name="CSG EPA" /> Leaks from the tank had caused the local groundwater to become contaminated with TCE and other [[volatile organic compounds]] (VOCs) in 1978.<ref name="CSG EPA" /> By 1999 GMT Microelectronics had {{US$|long=no|21 million}} in revenues and 183 employees working on the site.{{citation needed|date=May 2019}} Announced in March 1999, GMT would have provided foundry services based on TelCom's [[Bipolar junction transistor|Bipolar]] and SiCr (silicon chromium) Thin Film Resistor processes and would have been a licensed alternate source for TelCom's Bipolar based products,<ref>{{cite web |url=https://www.eetimes.com/document.asp?doc_id=1121054# |title= GMT signs bi-polar foundry deal with TelCom |publisher=Electronic Engineering Times |access-date=May 23, 2019}}</ref> with production running at 10,000 5-inch [[semiconductor wafers]] per month, producing [[CMOS]], BiCMOS, NMOS, bipolar and SOI ([[silicon on insulator]]) devices. In 2000, GMT Microelectronics discontinued operations and abandoned all of its assets at the Commodore Semiconductor Group [[superfund]] site.<ref name="CSG EPA" /> <!-- However, in 2001 the EPA shut the plant down due to the leaking of their underground hazardous waste storage tanks. GMT Microelectronics ceased operations and was liquidated.{{citation needed|date=December 2017}} {{Commenting out two sentences May 28, 2019 - this sentence has been marked as citation needed for a year and a half and there's contradictory information that says GMT abandoned the location but persisted as a company until they were acquired by someone else and this article isn't about GMT Microelectronics}} -->