Editing Risc PC (section)

{{Short description|Family of personal computers}}
{{Use dmy dates|date=November 2017}}
{{multiple issues|
{{refimprove|date=February 2021}}
{{Prose|date=January 2011}}
}}
{{Infobox information appliance
| name = Risc PC
| logo = [[File:Acorn risc pc logo.svg|100px]]
| image = [[File:Acorn Risc PC 600.jpg|250px]]
<!-- include the [[File:]] tag -->| caption = Acorn Risc PC 600 with two case slices, 3.5-inch disk drive and DVD-ROM drive
<!-- include if image is not a logo -->| developer = [[Acorn Computers]]
| manufacturer = [[Acorn Computers]], [[Castle Technology]]<ref name="Acorn press release 1998-10-12">{{cite news | author = Acorn Computers Ltd | title = Acorn announces distribution deal with Castle Technology for RISC based products | date = 1998-10-12 | publisher = Acorn Computers Ltd | url = http://www.acorn.co.uk/acorn/news/press/castle.html | work = Press release | access-date = 2011-01-06 | quote = (October 12th 1998), Cambridge, UK-Acorn announced today that it has completed negotiations with Castle Technology for them to distribute Acorn products. | archive-url = https://web.archive.org/web/19990506180305/http://www.acorn.co.uk/acorn/news/press/castle.html | archive-date = 1999-05-06}}</ref>
| family = 
| type = 
| generation = 
| releasedate = {{Start date and age|1994|04|15|df=y}}
| lifespan = 
| price = <!-- this is price at initial release, not the current price -->
| discontinued = {{Start date|2003|11|11|df=y}}<ref name="CastlePress 2003-11-11">{{Cite newsgroup
 | title         = Risc PC to Cease Production
 | author        = Mike Williams
 | date          = 11 November 2003
 | newsgroup     = comp.sys.acorn.announce
 | message-id    = slrnbr2fvo.ngt.n.g.boalch@compsoc.dur.ac.uk
 | url           = https://groups.google.com/d/msg/comp.sys.acorn.announce/jj28EsPTBYY/sibw4WJA8-kJ
 | access-date   = 30 August 2019}}</ref>
| unitssold = 
| unitsshipped = 
| media = 
| os = [[RISC OS]]
| power = 
| cpu = [[ARM core|ARMv3/ARMv4]]
| memory = 
| storage = 
| display = 
| graphics = VIDC20
| sound = 
| input = 
| controllers = 
| camera = 
| touchpad = 
| connectivity = 
| service = <!-- online service/s offered -->
| dimensions = {{plainlist|
*{{convert|117|mm|in|abbr=on}}&nbsp;''(h)''
*{{convert|355|mm|in|abbr=on}}&nbsp;''(w)''
*{{convert|384|mm|in|abbr=on}}&nbsp;''(d)''}}
| weight = 
| topgame = 
| compatibility = 
| predecessor = [[Acorn Archimedes|Archimedes]] series
| successor = [[Phoebe (computer)|Phoebe]], [[Iyonix PC]], [[A9home]]
<!-- predecessors / successors listed chronologically -->| related = [[Acorn A7000|A7000]]
| website = {{web archive|url=https://web.archive.org/web/19980202060639/http://www.acorn.com/acorn/products/desktop/section.cgi?section=rpc|title=acorn.com}}
| carrier = 
| location = <!-- GPS or Wi-Fi based -->
| output = 
}}

'''Risc PC''' was a range of personal computers launched in 1994 by [[Acorn Computers|Acorn]], replacing the [[Acorn Archimedes|Archimedes]] series. The machines use the Acorn developed [[ARM architecture family|ARM]] CPU and were thereby not [[IBM PC–compatible|IBM PC-compatible]].<ref name="AcornDevNews 33, 1994-04-30">{{cite news |date=1994-04-30 |title=Acorn launches the Risc PC |work=Developers' Newsletter No. 33 – April 1994 |publisher=[[Acorn Computers]] |url=http://chrisacorns.computinghistory.org.uk/docs/Acorn/DN/Acorn_DevNL33.pdf |access-date=2018-01-26 |quote=... on Friday April 15th ...}}</ref><ref name="chris-rpc">{{cite web |year=2009 |title=Chris's Acorns: Risc PC Computers |url=http://chrisacorns.computinghistory.org.uk/Computers/RiscPCComputers.html |access-date=2018-01-26 |publisher=Chris Whytehead}}</ref> 

At launch, the original Risc PC 600 model was fitted as standard with an ARM 610, a 32-bit RISC CPU with 4&nbsp;KB of cache and clocked at 30&nbsp;MHz. CPU technology advanced rapidly in this period though and within only two years a DEC [[StrongARM]] could be installed at 233&nbsp;MHz which was around 8 times faster.<ref>{{Cite web |title=RiscPC processors - ARM 610, ARM710 and StrongARM |url=https://www.retro-kit.co.uk/page.cfm/content/RiscPC-processors/index.html#StrongARM |access-date=2023-09-11 |website=www.retro-kit.co.uk}}</ref>

The machines were supplied with the [[RISC OS]] operating system which has a windowed cooperative multi-tasking design. Unusually for a PC of the period the O/S was stored in [[Read-only memory|ROM]], which enabled a relatively fast boot time. In addition Acorn sold a Virtual PC package that permitted x86 applications to be run in a virtual machine, they also supported the development of an ARM Linux distribution, from 1996.<ref>{{Cite web |title=Interview with Russell King, originator of the ARM Linux port [kerneltrap] |url=https://linuxdevices.org/interview-with-russell-king-originator-of-the-arm-linux-port-kerneltrap/ |access-date=2025-02-19}}</ref>

In contrast to most contemporary IBM clones, the machines supported multiple processors as a standard feature. Secondary (or "guest") CPUs did not need to be ARM based and could be an entirely different architecture. It was possible to add an [[x86]] CPU which enabled use of operating systems including [[DOS]] and [[Windows 95]]. Cards could often be added to other machines of the era to run DOS software but more usually these would implement the majority of an IBM PC clone on the card. The Risc PC required only the addition of the relevant CPU with some interface logic.

Alternate operating systems ran concurrently with RISC OS in a window. Applications from both operating systems could run at the same time in a similar fashion to a [[virtual machine]] with data shared between them. While now a ubiquitous technology, this was a less common feature in 1994 and more usually only one operating system would run at once on a single PC.

The Risc PC had a novel case design where additional chassis, known as "slices", could be stacked on top of each other, expanding the height of the machine. Up to six additional slices could be stacked, each containing additional drives or expansion cards (known as "podules"). At the time the IBM clone industry was standardised around the PCI bus, but Acorn used its own bus implementation that was not compatible and required its own unique expansion cards. The machines did use the then industry standard IDE or [[SCSI]] drives found in contemporary PCs. 

Acorn discontinued production of the Risc PC in 1998 after a corporate reorganisation but [[Castle Technology]] continued manufacturing the machines until 2003 and subsequently then produced their own similar designs. RISC OS is still available after becoming an open source product.<ref>{{Cite web |title=RISC OS Open: Welcome |url=https://www.riscosopen.org/content/ |access-date=2023-09-10 |website=www.riscosopen.org}}</ref>