View source for Risc PC

{{Short description|Family of personal computers}}
{{Use dmy dates|date=November 2017}}
{{Infobox personal computer
| 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 press release | 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 | access-date = 2011-01-06 | quote = 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 = 
| release_date = {{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
 | first         = Mike | last = 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>
| units_sold = 
| units_shipped = 
| media = 
| os = [[RISC OS]]
| power = 
| cpu = [[ARM core|ARMv3/ARMv4]]
| memory = 
| storage = 
| display = 
| graphics = VIDC20
| sound = 
| input = 
| controllers = 
| camera = 
| touchpad = 
| connectivity = 
| online_services = <!-- 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 = 
| top_game = 
| compatibility = 
| predecessor = [[Acorn Archimedes|Archimedes]] series
| successor = [[Phoebe (computer)|Phoebe]] (cancelled), [[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''' is<!--Although discontinued, they still exist. Past tense is inappropriate.--> a range of personal computers launched in 1994 by [[Acorn Computers|Acorn]], replacing the [[Acorn Archimedes|Archimedes]] series. The machines use an [[ARM architecture family|ARM]] CPU, developed by Acorn spinoff company [[Arm Holdings|ARM]], 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 |issue=33 |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 |website=Chris's Acorns |title=Risc PC Computers |url=http://chrisacorns.computinghistory.org.uk/Computers/RiscPCComputers.html |access-date=2018-01-26 |first=Chris |last=Whytehead}}</ref><!--SPS exception for subject matter expert-->

At launch, the original Risc PC 600 model was fitted as standard with an ARM 610, a 32-bit RISC CPU (with 26-bit address bus) 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=Retro-kit}}</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.

Alternative 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 [[Peripheral Component Interconnect|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 |website=RISC OS Open |title=Welcome |url=https://www.riscosopen.org/content/ |access-date=2023-09-10}}</ref>

== Technical specifications ==
[[File:riscpc internal.jpg|thumb|Risc PC with lid removed, showing fixing lugs. The top slice has not been internally sprayed for RF shielding.]]
[[File:Acorn-Risc-PC-ARM710-CPU.jpg|thumb|An ARM 710 CPU card for the Risc PC]]
[[File:Acorn ACA56 Risc PC x86 Card box open.jpg|thumb|The Acorn ACA56 Acorn PC card upgrade, showing the user guide, software disc, and card itself]]
{{unordered list
| '''CPU''': Dual-processor slots, one host processor and one guest processor.
{{unordered list
| '''Host processors''':
{{unordered list
| [[ARM architecture|ARM]]610 at 30&nbsp;MHz or 33&nbsp;MHz
| ARM710 at 40&nbsp;MHz
| [[StrongARM]] at 203&nbsp;MHz, 236&nbsp;MHz or 300&nbsp;MHz.
| Additionally prototypes of 33&nbsp;MHz ARM700 and 55&nbsp;MHz ARM810 processors were developed by Acorn, but not released.}}
| '''Guest processors''':
{{unordered list
| [[Intel 80486|486]]-class<ref name="independent holds right cards">{{cite news | url=https://www.independent.co.uk/extras/indybest/gadgets-tech/computers-system-that-holds-the-right-cards-1370124.html | title=Computers: System that holds the right cards | work=[[The Independent]] | date=1994-04-15 | access-date=6 September 2011 | author=Penman, Danny | location=London | quote=The modular design of the new computer allows a PC 486 processor to be added using a card ...}}</ref> and at least [[IBM 5x86C]]<ref>{{Cite web|url=https://www.ebay.com/itm/Used-Acorn-586-ACA57-Risc-PC-IBM-5x86C-100MHz-Second-Generation-PC-Card-/172405511966|title=Used Acorn 586 ACA57 Risc PC IBM 5x86C 100MHz Second Generation PC Card|website=eBay|language=en|quote=IBM 5x86C 100MHz Second Generation PC Card|access-date=2017-11-08}}</ref> co-processors at up to 133&nbsp;MHz. These ''PC cards'' and software allow PC compatible software to be run.
| [[digital signal processor|DSP]] chips (third party) were also available.{{Citation needed|date=February 2014}}}}}}

| '''Memory type''': Two 72-pin FPM [[SIMM]] slots, supporting a maximum memory size of 256&nbsp;MiB.
| '''Video subsystem''': [[VIDC20]] controller, with optional dual-port VRAM up to 2&nbsp;MiB.<ref name="apdl acorn appnote 254">{{cite web|title=APDL RiscWorld|url=http://www.apdl.org.uk/riscworld/volumes/volume4/issue4/makemode2/index.htm|work=Application Note 254|publisher=[[Acorn Computers]]|access-date=30 August 2019|date=9 June 2003}}</ref>
| '''Expansion''': [[Eurocard (printed circuit board)|Eurocard]]-sized [[Podule (expansion card)|Podule]] support in common with Archimedes-series machines. The Risc PC also offers DMA support in the first two podules on the bus. Third parties produced similar cards.
| '''Operating system''': [[RISC OS]], stored in 4&nbsp;MiB ROM (RISC OS 3.50 shipped on 2&nbsp;MiB ROMs) supplemented by disc-based components.
{{unordered list
| Fitted as standard:
{{unordered list
| RISC OS 3.50 (Risc PC 600)
| RISC OS 3.60 (Risc PC 700)
| RISC OS 3.70 (StrongARM Risc PC)
| RISC OS 3.71 (StrongARM Risc PC J233)
| RISC OS 4.03 (Kinetic Risc PC)}}
| RISC OS 4, RISC OS Select, RISC OS Adjust and RISC OS 6 are available from [[RISCOS Ltd]] as a replacement for the Acorn-implemented versions.<ref name=chris-rol>{{cite web|title=Chris's Acorns: RISC OS Ltd|url=http://chrisacorns.computinghistory.org.uk/AfterAcorn/RISCOSLtd.html|publisher=Chris Whytehead|year=2009|access-date=2018-01-26}}</ref>
| RISC OS 5 from [[RISC OS Open]] with the CPU running in 32-bit mode.
| [[Linux]]
| [[NetBSD]]<ref name=netbsd>{{cite web|title=NetBSD/acorn32|url=http://www.netbsd.org/ports/acorn32|publisher=NetBSD|year=2009|access-date=13 August 2009}}</ref>}}
| '''Case''': Designed by industrial designer [[Allen Boothroyd]]<ref name="pcw burley 199406">{{cite news | url=http://chrisacorns.computinghistory.org.uk/docs/Mags/PCW/PCW_Jun94_RPC600.pdf | title=Acorn RISC PC 600 | work=[[Personal Computer World]] | date=June 1994 | access-date=30 August 2013 | author=Burley, Ian}}</ref> of Cambridge Product Design (designer of the BBC Micro case). Custom plastic-based design with a 'slice' feature which allows extra case modules to be added to increase internal expansion space. Each slice adds two podule bays at the rear, and two [[drive bay]]s (one 3.5-inch, one 5.25-inch) at the front, covered by a retractable flap to hide cosmetic inconsistencies in hue. Some slices were internally sprayed with nickel paint to meet electromagnetic and radio emissions regulations.
| '''CD-ROM drive''': Optional extra, offering limited compatibility with [[multimedia]] PC [[CD-ROM]]s.<ref name="tes misguided loyalties">{{cite news | url=http://www.tes.co.uk/article.aspx?storycode=94608 | title=Trading on misguided loyalties? | work=[[Times Educational Supplement]] | date=20 October 1995 | access-date=10 November 2011 | author=Lambert, Andy | quote=Acorn has been pressed to give its users access to Windows Multimedia PC CDs ... there are still doubts about full compatibility.}}</ref>
| '''Ports''': [[RS-232]] serial, parallel, [[PS/2 port|PS/2]] keyboard, Acorn mouse, headphone audio out, [[D-subminiature|DE15]] [[Video Graphics Array|VGA]], network (optional).
| '''Additional configurations''':
{{unordered list
| Hydra multi-processor development system from Simtec. This plugged into the front processor slot and propagated the two original slots from the standard Risc PC, adding five extra slots, four being used by processor cards (these being the existing ARM610 or ARM710 cards at that time) with one slot accepting a static RAM card acting as a cache or shared memory. The Hydra card provided arbitration logic to manage the multiprocessor functionality, avoiding the need for each processor card to have such logic (as was the case with the 486 processor card which had an ASIC for this purpose), thus providing the hardware basis of a multiprocessing solution for the Risc PC. Simtec were considering Taos and Helios as potential operating systems to make use of the card.<ref name="acornuser199512">{{ cite news | url=https://archive.org/details/AcornUser162-Dec95/page/n8/mode/1up | title=Simtec multi-processor board arrives | work=Acorn User | date=December 1995 | access-date=1 April 2021 | pages=9 }}</ref> }}
| '''Dimensions''': 117 (182 for two centre-sections) × 355 × 384&nbsp;mm (H×W×D).}}

== Use ==
[[File:Omnibus RiscPC.jpg|thumb|upright|Customised Risc PC, running OmniBus Systems's OUI software, shown here in a training centre]]

The Risc PC was used by music composers and scorewriters to run the [[Sibelius (computer program)|Sibelius]] scorewriting software.<ref name="guardian20011101_sibelius">{{cite news | url=https://www.theguardian.com/technology/2001/nov/01/onlinesupplement3 | first1=Derek | last1=Bourgeois | title=Score yourself an orchestra | date=11 November 2001 | work=The Guardian | access-date = 10 May 2011 | quote=Many composers bought an Archimedes simply to have access to the program.}}</ref>

Between 1994 and 2008, the Risc PC and [[Acorn A7000|A7000+]] were used in television for broadcast automation, programmed by the UK company OmniBus Systems: once considered "the world leader in television station automation" and at one point automating "every national news programme on terrestrial television in the United Kingdom".<ref name="guardian19990105_omnibus">{{ cite news | url=https://www.theguardian.com/business/1999/jan/05/11 | title=Radio ham makes the TV news | work=The Guardian | date=5 January 1999 | access-date=31 March 2022 | last1=Nightingale | first1=Julie }}</ref> The Risc PC, in the form of the OmniBus Workstation, and a customised version of the A7000+ built into a 19-inch rack mount unit, known as the OmniBus Interface Unit, were used to control/automate multiple television broadcast devices from other manufacturers in a way that was unusual at the time. In 2002, OmniBus products were "in constant use worldwide at nearly 100 broadcasters" including the BBC and ITN.<ref name="riscos_brochure">{{ cite book | url=http://www.riscos.com/the_archive/rol/brochure/a4.pdf | title=RISC OS Promotional Brochure | publisher=RISCOS Ltd | date=14 August 2002 | access-date=31 March 2022 }}</ref>{{rp|pages=2}}

== {{anchor|Podule}} Timeline ==
* 1994 – Risc PC 600 launched, featuring a 30&nbsp;MHz ARM610 CPU.<ref name="chris-rpc"/>
* 1995 – 40&nbsp;MHz ARM710 CPU upgrade and Risc PC 700 model launched.<ref name="chris-rpc"/><ref name="acornuser199512_arm710">{{ cite news | url=https://archive.org/details/AcornUser162-Dec95/page/n50/mode/1up | title=ARM710 upgrade | work=Acorn User | date=December 1995 | access-date=15 November 2021 | last1=Barlow | first1=Richard | pages=51 }}</ref>
* 1996 – 200&nbsp;MHz StrongARM CPU upgrade released, offering a five-fold increase in raw processing power compared to the ARM7 used in the previous high-end machines.<ref name=chris-sa>{{cite web|title=Chris's Acorns: ART StrongARM CPU|url=http://chrisacorns.computinghistory.org.uk/32bit_UpgradesA2G/Acorn_ART10_StrongARM202.html|publisher=Chris Whytehead|year=2009|access-date=2018-01-26}}</ref>
* 1997 – Acorn launch Acorn J233 StrongARM Risc PC, featuring an uprated 233&nbsp;MHz model of StrongARM and including Browser and Java software.<ref>{{cite web|first=Chris|last=Whytehead|title=Acorn J233 StrongARM Risc PC|url=http://chrisacorns.computinghistory.org.uk/Computers/SARiscPCJ233.html}}</ref>
* 1998 – [[Castle Technology]] acquire the rights to continue to market and produce the Risc PC during the breakup of Acorn Computers.<ref name=drobe-cease>{{cite web|title=Castle bids farewell to Risc PC|url=http://www.drobe.co.uk/article.php?id=869|publisher=[[Drobe]]|date=11 November 2003|first=Chris|last=Williams|access-date=2019-08-30|archive-date=29 August 2016|archive-url=https://web.archive.org/web/20160829033155/http://www.drobe.co.uk/article.php?id=869|url-status=dead}}</ref>
* 2000 – In May, Castle Technology reveal the Kinetic Risc PC range which included a faster processor card with onboard memory.<ref name=iconbar-kinetic>{{cite web|title=Castle reveal Kinetic to the press|url=http://www.iconbar.com/forums/viewthread.php?newsid=918|publisher=[[The Icon Bar]]|date=9 May 2000|first=Alasdair|last=Bailey|access-date=13 August 2009}}</ref>
* 2001 – Viewfinder Podule, AGP adapter allows the use of IBM PC clone AGP graphics cards (e.g. a range of ATI Rage and Radeon).<ref name=drobe-viewfinder>{{cite web|title=Viewfinder 2 revealed|url=http://www.drobe.co.uk/article.php?id=352|publisher=[[Drobe]]|date=19 January 2002|access-date=30 August 2019}}</ref>
* 2003 – Castle Technology announce the end of production and sale of the Risc PC.<ref name=drobe-cease/>

== Risc PC 2 ==
{{Main|Phoebe (computer)}}
Acorn set about designing the [[Phoebe (computer)|Risc PC 2]], later renamed to Phoebe 2100{{snd}} a design with a 64&nbsp;MHz front-side bus, [[Peripheral Component Interconnect|PCI]] slots, and a yellow [[NLX (motherboard form factor)|NLX]] [[Computer form factor|form-factor]] case.<ref name=clan-aug-1998>{{cite web|title=Clan Newsletter August 1998|url=http://www.iconbar.com/forums/viewthread.php?newsid=1082#cn5|publisher=Acorn Computers|date=August 1998|access-date=19 August 2009}}</ref> Slated for release in late 1998, the project was abandoned just before completion, when Acorn's Workstation Division was closed. Only two prototypes were ever built, and one was publicly displayed for historical interest at the RISC OS 2001 show in [[Berkshire]], England.<ref name=drobe-rpc2-at-show>{{cite web|title=Risc PC 2 at RISC OS 2001|url=http://www.drobe.co.uk/article.php?id=337|publisher=[[Drobe]]|year=2001|access-date=13 August 2009}}</ref> The remaining cases were bought by CTA Direct who sold them off to the public.<ref name="iconbar=phoebe-case">{{cite web|title=Phoebe cases on sale|url=http://www.iconbar.com/articles/Phoebe_cases_on_sale/index37.html|publisher=[[The Icon Bar]]|date=12 August 2000|first=Richard|last=Goodwin|access-date=19 August 2009}}</ref>

== After Acorn ==
In 2003 it was confirmed that no more Risc PCs would be produced.<ref name=drobe-cease/> However RISC OS computers based on other ARM processors machines have been manufactured by companies since this date.

* [[Castle Technology]] – [[Iyonix PC]] based on the [[Intel XScale]] ARM processor and PCI [[Computer bus|bus]]
* [[Advantage Six]] – [[A9home]] based on the [[Samsung]] S3C2440 ARM processor
* [[RiscStation]] – [[R7500]] based on the ARM7500-FE processor

Significantly better performance has been reached on the aged Risc PC design by using the newer 203 (and later 236) MHz StrongARM CPU, using third-party [[video card]]s, [[overclocking]], and having specially designed CPU cards with [[random-access memory|RAM]] located upon them to sidestep the speed bottleneck of the slow system bus.

== Limitations ==
The 16&nbsp;MHz [[front-side bus]] is usually recognised as being the most significant fault of the computer; and the arrival of the (five times faster) [[StrongARM]] processor in 1996 meant that the Risc PC had a [[Central processing unit|CPU]] significantly faster than the computer had been designed for. Acorn had originally expected ARM&nbsp;CPUs to progress from the 30&nbsp;MHz ARM6 to the 40&nbsp;MHz ARM7, and then onto the ARM8 cores, which at the time were clocked at around 50–80&nbsp;MHz. In 2000, Castle released "Kinetic", a new StrongARM processor board with its own onboard memory slots augmenting main memory, reducing the need to negotiate the slow front-side bus for memory accesses.

The podule bus on the Risc PC can achieve a maximum data throughput of approximately 6100&nbsp;KByte/s. It is 32-bit and Risc PC predecessors have a 16-bit bus.<ref>{{cite web|url=http://www.drobe.co.uk/article.php?id=1076|title=Podule Bus review|date=2 June 2004|publisher=[[Drobe]]|first1=Andrew|last1=Hill|first2=Chris|last2=Williams|access-date=30 August 2019}}</ref> For comparison, the [[conventional PCI|PCI bus]], which was available in systems at the time of the Risc PC's introduction, is over 20 times faster. The transfer of 650&nbsp;MB would take 2 minutes via podule, compared to 5 seconds via PCI.

== See also ==
* [[Acorn A7000]]

== References ==
{{Reflist}}

== External links ==
* [https://web.archive.org/web/20161028092657/https://www.d1.dion.ne.jp/~r_high/memorial/rocketship.html Acorn's 10-slice ''Rocket Ship'' Risc PC, including pizza oven and kitchen sink]
* [https://www.iconbar.com/hardware/kinetic/ Castle reveal Kinetic Risc PC to the press]
* [https://www.iconbar.com/Happy_10th_Birthday_Risc_PC/news430.html Risc PC 10th Birthday]
* [https://www.iconbar.com/R.I.P.__Risc_PC/news374.html Risc PC production ceases]

{{Acorn computers, clones and compatibles}}
{{RISC OS}}

{{DEFAULTSORT:Risc Pc}}
[[Category:Acorn Computers]]<!-- may need focusing -->
[[Category:RISC OS]]
[[Category:ARM-based home computers]]
[[Category:Personal computers]]
[[Category:Computers designed in the United Kingdom]]
[[Category:Computer-related introductions in 1994]]
[[Category:32-bit computers]]