Editing ARM architecture family (section)

===Acorn Business Computer===
{{Main|Acorn Business Computer}}
1981 was also the year that the [[IBM Personal Computer]] was introduced. Using the recently introduced [[Intel 8088]], a [[16-bit computing|16-bit]] CPU compared to the 6502's [[8-bit computing|8-bit]] design, it offered higher overall performance. Its introduction changed the desktop computer market radically: what had been largely a hobby and gaming market emerging over the prior five years began to change to a must-have business tool where the earlier 8-bit designs simply could not compete. Even newer [[32-bit computing|32-bit]] designs were also coming to market, such as the [[Motorola 68000]]<ref>{{cite web |last=Polsson |first=Ken |title=Chronology of Microprocessors |url=https://processortimeline.info/ |url-status=live |archive-url=https://web.archive.org/web/20180809022013/http://processortimeline.info/ |archive-date=2018-08-09 |access-date=2013-09-27 |website=Processortimeline.info}}</ref> and [[National Semiconductor NS32016]].<ref name="leedy198304">{{cite news |last=Leedy |first=Glenn |date=April 1983 |url=https://archive.org/details/byte-magazine-1983-04/page/n53/mode/2up |title=The National Semiconductor NS16000 Microprocessor Family |work=Byte |access-date=22 August 2020 |pages=53–66}}</ref>

Acorn began considering how to compete in this market and produced a new paper design named the [[Acorn Business Computer]]. They set themselves the goal of producing a machine with ten times the performance of the BBC Micro, but at the same price.{{sfn|Evans|2019|loc=6:00}} This would outperform and underprice the PC. At the same time, the recent introduction of the [[Apple Lisa]] brought the [[graphical user interface]] (GUI) concept to a wider audience and suggested the future belonged to machines with a GUI.<ref>{{cite news |url=https://www.electronicsweekly.com/Articles/29/04/1998/7242/ARM39s-way.htm |title=ARM's way |work=[[Electronics Weekly]] |date=29 April 1998 |access-date=26 October 2012 |author=Manners, David |url-status=dead |archive-url=https://web.archive.org/web/20120729024818/http://www.electronicsweekly.com/Articles/29/04/1998/7242/ARM39s-way.htm |archive-date=29 July 2012}}</ref> The Lisa, however, cost $9,995, as it was packed with support chips, large amounts of memory, and a [[hard disk drive]], all very expensive then.{{sfn|Evans|2019|loc=5:30}}

The engineers then began studying all of the CPU designs available. Their conclusion about the existing 16-bit designs was that they were a lot more expensive and were still "a bit crap",{{sfn|Evans|2019|loc=7:45}} offering only slightly higher performance than their BBC Micro design. They also almost always demanded a large number of support chips to operate even at that level, which drove up the cost of the computer as a whole. These systems would simply not hit the design goal.{{sfn|Evans|2019|loc=7:45}} They also considered the new 32-bit designs, but these cost even more and had the same issues with support chips.{{sfn|Evans|2019|loc=8:30}} According to [[Sophie Wilson]], all the processors tested at that time performed about the same, with about a 4&nbsp;Mbit/s bandwidth.<ref>{{cite AV media |url=https://www.youtube.com/watch?v=D4nWLIeBuf4 |archive-url=https://ghostarchive.org/varchive/youtube/20211211/D4nWLIeBuf4 |archive-date=2021-12-11 |url-status=live |title=Sophie Wilson at Alt Party 2009 (Part 3/8)}}{{cbignore}}</ref>{{efn|Using 32-bit words, 4&nbsp;Mbit/s corresponds to 1 [[Instructions per second#Millions of instructions per second (MIPS)|MIPS]].}}

Two key events led Acorn down the path to ARM. One was the publication of a series of reports from the [[University of California, Berkeley]], which suggested that a simple chip design could nevertheless have extremely high performance, much higher than the latest 32-bit designs on the market.<ref name="informit">{{cite book |last=Chisnall |first=David |date=23 August 2010 |url=https://www.informit.com/articles/article.aspx?p=1620207 |title=Understanding ARM Architectures |access-date=26 May 2013}}</ref> The second was a visit by [[Steve Furber]] and Sophie Wilson to the [[Western Design Center]], a company run by [[Bill Mensch]] and his sister, which had become the logical successor to the MOS team and was offering new versions like the [[WDC 65C02]]. The Acorn team saw high school students producing chip layouts on Apple II machines, which suggested that anyone could do it.{{sfn|Evans|2019|loc=9:00}}<ref>{{cite book |last=Furber |first=Stephen B. |year=2000 |title=ARM system-on-chip architecture |publisher=Addison-Wesley |location=Boston |isbn=0-201-67519-6 |title-link=ARM system-on-chip architecture}}</ref> In contrast, a visit to another design firm working on modern 32-bit CPU revealed a team with over a dozen members who were already on revision H of their design and yet it still contained bugs.{{efn|Available references do not mention which design team this was, but given the timing and known history of designs of the era, it is likely this was the National Semiconductor team whose NS32016 suffered from a large number of bugs.}} This cemented their late 1983 decision to begin their own CPU design, the Acorn RISC Machine.{{sfn|Evans|2019|loc=9:50}}