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===Very Large Scale Integration===
[[Image:Diopsis.jpg|thumb|right|A VLSI integrated-circuit [[die (integrated circuit)|die]] ]]
A major milestone in software development was the invention of the [[Very Large Scale Integration]] (VLSI) circuit (1964).<ref name="digibarn_bp">{{cite web
| url=https://www.digibarn.com/stories/bill-pentz-story/index.html#story
| title=Bill Pentz — A bit of Background: the Post-War March to VLSI
| publisher=Digibarn Computer Museum
| date=August 2008
| access-date=January 31, 2022
| archive-date=March 21, 2022
| archive-url=https://web.archive.org/web/20220321183527/https://www.digibarn.com/stories/bill-pentz-story/index.html#story
| url-status=live
}}</ref> Following [[World War II]], tube-based technology was replaced with [[point-contact transistor]]s (1947) and [[bipolar junction transistor]]s (late 1950s) mounted on a [[circuit board]].<ref name="digibarn_bp"/> [[Invention of the integrated circuit|During the 1960s]], the [[aerospace]] industry replaced the circuit board with an [[integrated circuit chip]].<ref name="digibarn_bp"/>
[[Robert Noyce]], co-founder of [[Fairchild Semiconductor]] (1957) and [[Intel]] (1968), achieved a technological improvement to refine the [[Semiconductor device fabrication|production]] of [[field-effect transistor]]s (1963).<ref name="digital_age">{{cite book
}}</ref> The MOS transistor is the primary component in ''integrated circuit chips''.<ref name="digital_age"/>
Originally, integrated circuit chips had their function set during manufacturing. During the 1960s, controlling the electrical flow migrated to programming a [[Diode matrix|matrix]] of [[read-only memory]] (ROM). The matrix resembled a two-dimensional array of fuses.<ref name="digibarn_bp"/> The process to embed instructions onto the matrix was to burn out the unneeded connections.<ref name="digibarn_bp"/> There were so many connections, [[firmware]] programmers wrote a ''computer program'' on another chip to oversee the burning.<ref name="digibarn_bp"/> The technology became known as [[Programmable ROM]]. In 1971, Intel [[stored-program computer|installed the computer program onto the chip]] and named it the [[Intel 4004]] [[microprocessor]].<ref name="intel_4004">{{cite web
| url=https://spectrum.ieee.org/chip-hall-of-fame-intel-4004-microprocessor
| title=Chip Hall of Fame: Intel 4004 Microprocessor
| access-date=February 5, 2022
}}</ref>
===Sac State 8008===
[[File:Sacstate 8008.jpg|thumb|Artist's depiction of Sacramento State University's Intel 8008 microcomputer (1972)]]
The Intel 4004 (1971) was a 4-[[bit]] microprocessor designed to run the [[Busicom]] calculator. Five months after its release, Intel released the [[Intel 8008]], an 8-bit microprocessor. Bill Pentz led a team at [[Sacramento State]] to build the first [[microcomputer]] using the Intel 8008: the ''Sac State 8008'' (1972).<ref name="cnet">{{cite web
| url=https://www.cnet.com/news/inside-the-worlds-long-lost-first-microcomputer/
| title=Inside the world's long-lost first microcomputer
| publisher=c/net
| date=January 8, 2010
| access-date=January 31, 2022
| archive-date=February 1, 2022
| archive-url=https://web.archive.org/web/20220201023538/https://www.cnet.com/news/inside-the-worlds-long-lost-first-microcomputer/
| url-status=live
}}</ref> Its purpose was to store patient medical records. The computer supported a [[disk operating system]] to run a [[Memorex]], 3-[[megabyte]], [[hard disk drive]].<ref name="digibarn_bp"/> It had a color display and keyboard that was packaged in a single console. The disk operating system was programmed using [[IBM Basic Assembly Language and successors|IBM's Basic Assembly Language (BAL)]]. The medical records application was programmed using a [[BASIC]] interpreter.<ref name="digibarn_bp"/> However, the computer was an evolutionary dead-end because it was extremely expensive. Also, it was built at a public university lab for a specific purpose.<ref name="cnet"/> Nonetheless, the project contributed to the development of the [[Intel 8080]] (1974) [[instruction set]].<ref name="digibarn_bp"/>
===x86 series===
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