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Several CPUs were considered, including the [[Texas Instruments TMS9900]], [[Motorola 68000]] and [[Intel 8088]]. The 68000 had 32 bit registers with a flat 24 bit address space for up to 16MB of memory and was considered the best choice,<ref name="millergates200119970325">{{Cite interview |last=Gates |first=Bill |interviewer=Michael J. Miller |title=Interview: Bill Gates, Microsoft |url=http://www.pcmag.com/article/0,2997,s=1754&a=11072,00.asp |date=March 25, 1997 |archive-url=https://web.archive.org/web/20010823113747/http://www.pcmag.com/article/0%2C2997%2Cs%3D1754%26a%3D11072%2C00.asp |archive-date=August 23, 2001 |access-date=September 4, 2020 |url-status=live |work= [[PCMag|PC Magazine]]}}</ref> but was not production-ready like the others.<ref name="rhines20170622">{{Cite news |last=Rhines |first=Walden C. |author-link=Walden C. Rhines |date=June 22, 2017 |title=The Inside Story of Texas Instruments' Biggest Blunder: The TMS9900 Microprocessor |language=en |work=[[IEEE Spectrum]] |url=https://spectrum.ieee.org/the-inside-story-of-texas-instruments-biggest-blunder-the-tms9900-microprocessor |access-date=July 8, 2017}}</ref> The [[IBM 801]] RISC processor was also considered, since it was considerably more powerful than the other options, but rejected due to the design constraint to use [[Commercial off-the-shelf |off-the-shelf]] parts{{dubious|date=February 2024|reason=According to wiki page [[IBM 801]] the processor wasn't production ready either}}. The TMS9900 had only 16 bits of address space which was the same as other 8 bit chips and was rejected as it was inferior to the Intel 8088 which had 20 bits of address space which could use one megabyte of memory.<ref>{{cite web | url=https://spectrum.ieee.org/the-inside-story-of-texas-instruments-biggest-blunder-the-tms9900-microprocessor | title=The Inside Story of Texas Instruments' Biggest Blunder: The TMS9900 Microprocessor - IEEE Spectrum }}</ref>
The Intel 8086 architecture had 16 bit registers and used a segment scheme to increase the address space to 20 bits or 1MB of memory which complicated programming but was a big step up from 64K limit of most 8 bit chips. IBM chose the 8088 8-bit bus variant of the 16 bit [[Intel 8086|8086]] because Intel offered a better price for the former and could provide more units,<ref name="freiberger19820823">{{cite news|author=Freiberger, Paul|date=August 23, 1982|title=Bill Gates, Microsoft and the IBM Personal Computer|page=22|work=InfoWorld|url=https://books.google.com/books?id=VDAEAAAAMBAJ&pg=PA22|access-date=January 29, 2015}}</ref> and the 8088's 8-bit bus reduced the cost of the rest of the computer. The 8088 had the advantage that IBM already had familiarity with the 8085 from designing the [[IBM System/23 Datamaster]]. The 62-pin expansion bus slots were also designed to be similar to the Datamaster slots,<ref>{{cite web|url=https://www.edn.com/whence-came-the-ibm-pc/|title=Whence Came the IBM PC|website=edn.com|date=September 15, 2001|access-date=October 13, 2020|author=John Titus}}</ref> and its keyboard design and layout became the [[IBM Model F|Model F]] keyboard shipped with the PC,<ref name="bradley199009">{{cite news | url=https://archive.org/stream/byte-magazine-1990-09/1990_09_BYTE_15-09_15th_Anniversary_Summit#page/n451/mode/2up | title=The Creation of the IBM PC | work=[[Byte (magazine)|Byte]] | date=September 1990 | access-date=April 2, 2016 | author=Bradley, David J. | pages=414–420}}</ref> but otherwise the PC design differed in many ways.
The 8088 motherboard was designed in 40 days,<ref>{{Cite news|title=Remembering the Beginning|work=PC Magazine|url=http://www.pcmag.com/article/0,2997,s=1754&a=11072,00.asp|url-status=dead|archive-url=https://web.archive.org/web/20020206040238/http://www.pcmag.com/article/0%2C2997%2Cs%3D1754%26a%3D11072%2C00.asp|archive-date=February 6, 2002|access-date=September 4, 2020}}</ref> with a working prototype created in four months,<ref name=nyt>{{Cite news|last=Sanger|first=David E.|date=August 5, 1985|title=Philip Estridge Dies in Jet Crash; Guided Ibm Personal Computer|language=en-US|work=The New York Times|url=https://www.nytimes.com/1985/08/05/us/philip-estridge-dies-in-jet-crash-guided-ibm-personal-computer.html|access-date=October 4, 2020|issn=0362-4331}}</ref> demonstrated in January 1981. The design was essentially complete by April 1981, when it was handed off to the manufacturing team.<ref>{{Cite web|date=January 23, 2003|title=IBM Archives: The birth of the IBM PC|url=https://www.ibm.com/ibm/history/exhibits/pc25/pc25_birth.html|access-date=October 4, 2020|website=www.ibm.com|language=en-US}}</ref> PCs were assembled in an IBM plant in Boca Raton, with components made at various IBM and third party factories. The monitor was an existing design from [[IBM Japan]]; the printer was manufactured by [[Epson]].<ref>{{Cite book|url=https://books.google.com/books?id=WSBVAAAAMAAJ&pg=RA1-PA128|title=U-M Computing News|date=1988|publisher=Computing Center|language=en}}</ref>{{fv|date=July 2023}} Because none of the functional components were designed by IBM, they obtained only a handful of patents on the PC, covering such features as the bytecoding for color monitors, DMA access operation, and the keyboard interface. They were never enforced. <ref name="R.Turner one attorney who obtained these patents for IBM.">{{Cite magazine|magazine=InfoWorld|url=https://books.google.com/books?id=VDAEAAAAMBAJ|page=[https://books.google.com/books?id=VDAEAAAAMBAJ&pg=PA29 21]|date=August 23, 1982|title=Let's Keep Those Systems Open|publisher=InfoWorld Media Group, Inc.|language=en|via=Google Books}}</ref>
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