Editing Microcontroller (section)

=== Development ===
One book credits [[Texas Instruments|TI]] engineers Gary Boone and Michael Cochran with the successful creation of the first microcontroller in 1971. The result of their work was the [[TMS 1000]], which became commercially available in 1974. It combined read-only memory, read/write memory, processor and clock on one chip and was targeted at embedded systems.<ref>{{cite book
 |chapter-url=http://smithsonianchips.si.edu/augarten/p38.htm
 |chapter=The Most Widely Used Computer on a Chip: The TMS 1000
 |title=State of the Art: A Photographic History of the Integrated Circuit
 |last=Augarten |first=Stan
 |publisher=Ticknor & Fields
 |location=New Haven and New York
 |year=1983
 |isbn=978-0-89919-195-9
 |access-date=2009-12-23
 |archive-url=https://web.archive.org/web/20100217065617/http://smithsonianchips.si.edu/augarten/p38.htm
 |archive-date=2010-02-17
 |url-status=dead
}}</ref>

During the early-to-mid-1970s, Japanese electronics manufacturers began producing microcontrollers for automobiles, including 4-bit MCUs for [[in-car entertainment]], automatic wipers, electronic locks, and dashboard, and 8-bit MCUs for engine control.<ref>{{cite web |title=Trends in the Semiconductor Industry |url=http://www.shmj.or.jp/english/trends/trd70s.html |website=Semiconductor History Museum of Japan |access-date=2019-06-27 |archive-url=https://web.archive.org/web/20190627082830/http://www.shmj.or.jp/english/trends/trd70s.html |archive-date=2019-06-27 |url-status=dead }}</ref>

Partly in response to the existence of the single-chip TMS 1000,<ref name=CMoral2008>{{cite web|url=http://archive.computerhistory.org/resources/access/text/2013/05/102658328-05-01-acc.pdf |title=Oral History Panel on the Development and Promotion of the Intel 8048 Microcontroller|work=Computer History Museum Oral History, 2008|access-date=2016-04-04|page=4}}</ref> Intel developed a computer system on a chip optimized for control applications, the [[Intel 8048]], with commercial parts first shipping in 1977.<ref name=CMoral2008/> It combined [[random-access memory|RAM]] and [[read-only memory|ROM]] on the same chip with a microprocessor. Among numerous applications, this chip would eventually find its way into over one billion PC keyboards. At that time Intel's President, Luke J. Valenter, stated that the microcontroller was one of the most successful products in the company's history, and he expanded the microcontroller division's budget by over 25%.

{{multiple image |total_width=420
 | image1   = PIC16CxxxWIN.JPG
 | caption1 = Various [[PIC microcontroller]]s with<br />integrated EPROM
 | image2   = Microcomputer with EPROM (piggyback).jpg
 | caption2 = Piggyback microcontroller from [[MOSTEK]]
}}

{{anchor|piggyback microcontroller}}
Most microcontrollers at this time had concurrent variants. One had [[EPROM]] program memory, with a transparent quartz window in the lid of the package to allow it to be erased by exposure to [[ultraviolet]] light. These erasable chips were often used for prototyping. The other variant was either a mask-programmed ROM or a [[Programmable read-only memory|PROM]] variant which was only programmable once. For the latter, sometimes the designation ''OTP'' was used, standing for "one-time programmable". In an OTP microcontroller, the PROM was usually of identical type as the EPROM, but the chip package had no quartz window; because there was no way to expose the EPROM to ultraviolet light, it could not be erased. Because the erasable versions required ceramic packages with quartz windows, they were significantly more expensive than the OTP versions, which could be made in lower-cost opaque plastic packages. For the erasable variants, quartz was required, instead of less expensive glass, for its transparency to ultraviolet light—to which glass is largely opaque—but the main cost differentiator was the ceramic package itself. '''Piggyback microcontrollers''' were also used.<ref>{{cite web |url=https://www.industrialalchemy.org/articleview.php?item=2028 |title=OKI Intel M85C154 Piggyback Microcontroller |website=industrialalchemy.org |access-date=2024-12-08}}</ref><ref>{{cite web |url=https://www.cpushack.com/2011/03/06/cpu-of-the-day-ns87p50r-6-piggyback-cpus/ |title=CPU of the Day: NS87P50R-6: Piggyback CPUs |website=cpushack.com |date=2011-03-06 |access-date=2024-12-08}}</ref><ref>{{cite web |url=https://www.allisdiy.com/main/piggyback-microcontroller |title=Piggyback microcontrollers |website=allisdiy.com |access-date=2024-12-08}}</ref>

In 1993, the introduction of [[EEPROM]] memory allowed microcontrollers (beginning with the Microchip [[PIC16x84|PIC16C84]])<ref name="pic16c84ref">{{cite web
 |url=https://spectrum.ieee.org/chip-hall-of-fame-microchip-technology-pic-16c84-microcontroller
 |title=Chip Hall of Fame: Microchip Technology PIC 16C84 Microcontroller
 |publisher=IEEE
 |access-date=September 16, 2018|date=2017-06-30
 }}</ref> to be electrically erased quickly without an expensive package as required for [[EPROM]], allowing both rapid prototyping, and [[in-system programming]]. (EEPROM technology had been available prior to this time,<ref name="mc68ch805ref">{{cite book |author=Motorola |title=Advance Information, 8-Bit Microcomputers MC68HC05B6, MC68HC05B4, MC68HC805B6, Motorola Document EADI0054RI |publisher=Motorola Ltd., 1988}}</ref> but the earlier EEPROM was more expensive and less durable, making it unsuitable for low-cost mass-produced microcontrollers.) The same year, Atmel introduced the first microcontroller using [[Flash memory]], a special type of EEPROM.<ref name="flash">{{cite web|title=Atmel's Self-Programming Flash Microcontrollers |url=https://ww1.microchip.com/downloads/en/DeviceDoc/doc2464.pdf |author=Odd Jostein Svendsli |date=2003 |access-date=2024-06-18}}</ref> Other companies rapidly followed suit, with both memory types.

Nowadays microcontrollers are cheap and readily available for hobbyists, with large online communities around certain processors.