Editing StrongARM RISC PC

{{Infobox computer
| name         = Acorn StrongARM Risc PC
| image        = [[File:Acorn StrongARM Risc PC.jpg|260px|frameless]]
| caption      = StrongARM Risc PC, model SRP26, running RISC OS 3.70 (photo: Chris Whytehead, CC BY-SA 3.0)
| manufacturer = Acorn Computers Ltd (Acorn Risc Technologies)
| type         = Desktop computer
| release date = September 1996<ref name="chrissa">Whytehead, Chris. [https://chrisacorns.computinghistory.org.uk/Computers/SARiscPC.html "StrongARM Risc PC"], Chris's Acorns (retrieved 2026-10-02). Launched September 1996; similar to the Risc PC 700 but with a 202 MHz StrongARM and RISC OS 3.70; models SRP05, SRP06, SRP10, SRP11, SRP15 and SRP16 at 202 MHz and SRP20, SRP20A, SRP21 and SRP26 at 233 MHz, differing in memory, hard disc and CD-ROM; one SRP26 with a 160 MHz part run at 202 MHz; two SRP26 machines photographed and specified: main board 1208,000 issue 3 with 16-bit sound, processor card 1111,150 issue 3, SA-110S and SA-110K processors, IOMD21 rev A, VIDC20, 16 MHz memory clock, 103 W power supply, Sony MPF920-H floppy, Seagate ST31276 hard disc, a corroded CMOS battery on one and a battery replaced by a rechargeable AAA cell on the other.</ref>
| cpu          = Digital StrongARM SA-110 at 202 MHz (233 MHz on later models), on a plug-in processor card
| memory       = 4 or 8 MB as supplied, with 2 MB of VRAM on some models
| storage      = 3.5-inch floppy; IDE hard disc; CD-ROM on some models
| display      = VIDC20
| sound        = 16-bit
| os           = RISC OS 3.70
| model        = SRP05, SRP06, SRP10, SRP11, SRP15, SRP16, SRP20, SRP20A, SRP21, SRP26
| predecessor  = [[Acorn Risc PC 700]]
}}
<templatestyles src="Template:StyledTable/styles.css" />
The '''StrongARM Risc PC''' is the version of Acorn's [[Acorn Risc PC 700|Risc PC]] fitted with a Digital StrongARM SA-110 processor card and RISC OS 3.70, launched in September 1996. Chris Whytehead describes it as similar to the Risc PC 700, with the 202&nbsp;MHz StrongARM and RISC OS 3.70 as the main differences; later models used a 233&nbsp;MHz part.<ref name="chrissa" /> Existing Risc PC 600 and 700 owners could fit the same StrongARM card and ROMs as an upgrade.<ref name="sa03">Acorn Risc Technologies, ''StrongARM Upgrade for Risc PC'', leaflet SA03, 1996, hosted as [[:File:ART StrongARM Upgrade for Risc PC leaflet (SA03).pdf]]. The upgrade for 30 MHz ARM610, 33 MHz ARM610 and 40 MHz ARM710 machines; a 200 MHz SA-110 card as a direct replacement for the existing processor card; a ROM set with a StrongARM-aware RISC OS containing the features of RISC OS 3.6; 350k Dhrystones, roughly 200 Dhrystone MIPS; !Draw interpolation 38.0 s on the ARM710 and 5.2 s on the StrongARM; an ArtWorks redraw 13.7 s and 3.0 s.</ref>

The case, main board, power supply, drives and battery arrangement are those of the Risc PC 700, so its maintenance, troubleshooting and capacitor guides apply: [[Acorn Risc PC 700 Maintenance Guide]], [[Acorn Risc PC 700 Troubleshooting Guide]] and [[Acorn Risc PC 700 Capacitor Guide]].

== Models ==

{| class="wikitable styled-table" style="width:70%; text-align:left;"
|+'''StrongARM Risc PC models (Chris's Acorns)'''
! Model !! Processor !! Memory !! Hard disc !! CD-ROM
|-
| SRP05 || 202 MHz || 8 MB, 2 MB VRAM || 1 GB || –
|-
| SRP06 || 202 MHz || 8 MB, 2 MB VRAM || 1 GB || 8×
|-
| SRP10 || 202 MHz || 4 MB || 1.2 GB || –
|-
| SRP11 || 202 MHz || 4 MB || 1.2 GB || 8×
|-
| SRP15 || 202 MHz || 8 MB, 2 MB VRAM || 1.2 GB || –
|-
| SRP16 || 202 MHz || 8 MB, 2 MB VRAM || 1.2 GB || 8×
|-
| SRP20 || 233 MHz || 4 MB || 1.2 GB || –
|-
| SRP20A || 233 MHz || 4 MB || 1.7 GB || –
|-
| SRP21 || 233 MHz || 4 MB || 1.2 GB || 8×
|-
| SRP26 || 233 MHz || Not listed || Not listed || Not listed
|}
Source: Chris's Acorns.<ref name="chrissa" /> The J233 Risc PC of 1997, with RISC OS 3.71 and a web browser and Java bundled, is described on [[Acorn J233]].

== Hardware ==

[[File:Acorn StrongARM Risc PC main board.jpg|thumb|right|300px|Issue 3 main board 1208,000: IOMD21, the two processor-card connectors, the RISC OS 3.70 ROMs, VIDC20, VRAM and RAM, and a corroded CMOS battery at the right (photo: Chris Whytehead, CC BY-SA 3.0)]]
Both StrongARM Risc PCs that Chris Whytehead examined have the issue 3 main board, part 1208,000, with 16-bit sound, the IOMD21 memory controller and VIDC20, and processor card part 1111,150 issue 3. The front processor connector carries the StrongARM card and the rear one takes an optional x86 PC card. The supply is rated 103&nbsp;W.<ref name="chrissa" />

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''StrongARM processor cards'''
! Card !! Notes
|-
| ART10, 200 MHz || Digital SA-110, supplied in the original upgrade packs and the first StrongARM Risc PCs
|-
| ART10, 233 MHz || Digital SA-110 revision S; used in later StrongARM Risc PCs
|-
| ART10 with a 160 MHz part || Found in one SRP26; reported by !Sick as 200 MHz, so run above its marking
|}
Sources: Chris's Acorns.<ref name="chris202">Whytehead, Chris. [https://chrisacorns.computinghistory.org.uk/32bit_UpgradesA2G/Acorn_ART10_StrongARM202.html "Acorn ART10 200MHz StrongARM CPU"], [https://chrisacorns.computinghistory.org.uk/32bit_UpgradesA2G/Acorn_ART10_StrongARM233.html "Acorn ART10 233MHz StrongARM CPU"] and [https://chrisacorns.computinghistory.org.uk/32bit_UpgradesA2G/Acorn_ART10_StrongARM160.html "Acorn ART10 160MHz StrongARM CPU"], Chris's Acorns (retrieved 2026-10-02). The 200 MHz card as supplied in the upgrade packs and first machines, with a Digital processor (later StrongARMs were made by Intel); the 233 MHz card with a revision S Digital part; the 160 MHz part from an SRP26 that !Sick reports as 200 MHz; performance over a 30 MHz ARM610 of about 750 % and more than 800 %.</ref><ref name="chrissa" />

Acorn's 1996 folder quotes 356,000 Dhrystones (204 MIPS) for the StrongARM Risc PC against 55,000 (32 MIPS) for the Risc PC 700, and processor power consumption under 1&nbsp;W.<ref name="folder">Acorn Risc Technologies, ''The StrongARM Risc PC'', folder, 6 pages, hosted as [[:File:Acorn StrongARM Risc PC brochure (ART).pdf]]. Dhrystone table (Risc PC 700 55k, 32 MIPS; StrongARM Risc PC 356k, 204 MIPS); processor power consumption under 1 W; modular case expandable to seven sections.</ref>

== Fitting or refitting the StrongARM card and ROMs ==

Acorn's upgrade pack held the processor card, two RISC OS 3.7 ROMs, four floppy discs with a new hard disc image, a CD-ROM and an anti-static wrist strap; a ROM extractor tool is needed.<ref name="inst">Acorn Computers, ''Acorn StrongARM card and RISC OS 3.7 Upgrade Instructions'', part no. 1403,222, issue 1, August 1996, hosted as [[:File:Acorn StrongARM Card and RISC OS 3.7 Upgrade Instructions.pdf]]. Pack contents, p. 1; overview and tools, p. 2; static precautions, p. 3; software installation with !Installer and the inactive resources directory $.InactivRes, pp. 4–7; hardware installation (ROMs 1203,191-xx in ROM 1 and 1203,192-xx in ROM 2, dimple to the left; card in PROC I/F slot 0; keep the old card), pp. 7–9; restart with Delete held for factory-default CMOS, p. 9; reconfiguration of !Boot, networking and printing, pp. 10–19.</ref> The same steps apply when a StrongARM machine's card or ROMs are reseated or replaced.

# Install the new hard disc resources first, from the floppies, with !Installer; the old !Boot, Apps, Printing and Utilities move to $.InactivRes and are not deleted.
# Switch off, remove the mains lead, take off the top cover and middle section, and clip the wrist strap to a metal earth point such as the serial port shell.
# Remove any expansion cards; Acorn recommends testing without them first.
# Lever out the old ROMs and fit the RISC OS 3.7 ROMs with the dimple to the left of the case: part 1203,191-xx in the socket marked ROM 1 and 1203,192-xx in ROM 2.
# Replace the processor card with the StrongARM card in the slot marked PROC I/F slot 0, and keep the old card.
# Refit the covers, then switch on holding Delete until the desktop appears, to start with factory-default CMOS settings.
# Reconfigure from !Boot. Acorn warns against reinstating old Choices settings.

Source: Acorn's instructions.<ref name="inst" /> A StrongARM machine whose CMOS settings have been lost can be reset the same way, by holding Delete at power-on.<ref name="inst" />

== Software compatibility ==

Programs that modify their own code can fail on the StrongARM. Acorn Risc Technologies' 1996 compatibility notes record that some early Aspex products used self-modifying code during start-up and would not run, that Acorn C/C++ needed a new shared C library supplied in the RISC OS 3.7 ROM, and that DDT and some TCP/IP applications needed patches; ART later issued a patch for Acorn Advance release 2.<ref name="artsw">Acorn Risc Technologies, ''Software Tested and Working on StrongARM'', 2 pages, 1996, [https://chrisacorns.computinghistory.org.uk/docs/Acorn/Tech/Acorn_ART_SWTestedonSA.pdf PDF at Chris's Acorns], and ART Engineering Support, [https://chrisacorns.computinghistory.org.uk/docs/Acorn/PR/Advance_patch_for_SA-110.txt "Advance patch for SA-110"] (both retrieved 2026-10-02). C/C++ changes confined to the shared C library in the RISC OS 3.7 ROM; a new DDT on the upgrade disc; TCP/IP Release 2 applications needing patches; early Aspex products using self-modifying code during initialisation; a patch for Acorn Advance Release 2.</ref>

== Maintenance notes ==

* Backup battery: as on the Risc PC 700, the 1208,000 board has a rechargeable cell for the clock and CMOS RAM, and it leaks. One of Chris Whytehead's SRP26 boards had a corroded battery and the other had had its battery replaced by a socketed rechargeable AAA cell wired to the board.<ref name="chrissa" /> See [[Acorn Risc PC 700 Maintenance Guide]] and [[Battery Refurbishment]].
* Front flap: Chris Whytehead notes that the spring holding up the front flap has broken on many Risc PCs, including one of his.<ref name="chrissa" />
* Processor card: handle it with static precautions and avoid touching the chip pins, as Acorn's instructions require.<ref name="inst" />

== Documentation ==

* [[StrongARM Risc PC Documentation]]: the documents below, with their contents.
* [[:File:Acorn StrongARM Card and RISC OS 3.7 Upgrade Instructions.pdf]]: Acorn's fitting instructions, 1403,222.
* [[:File:ART StrongARM Upgrade for Risc PC leaflet (SA03).pdf]] and [[:File:Acorn StrongARM Risc PC brochure (ART).pdf]]: ART's 1996 leaflet and folder.
* [[Acorn Risc PC Technical Reference Manual]]: Acorn's Risc PC hardware reference (for the earlier 0197,000 board).

== Gallery ==
<gallery mode="packed" heights="200">
File:Acorn StrongARM Risc PC with top cover removed.jpg|Top cover removed: PC card and 233 MHz StrongARM card at top left, two-slot backplane, 103 W supply on the right
File:Acorn StrongARM Risc PC main board.jpg|Issue 3 main board 1208,000
</gallery>
Photographs: Chris Whytehead, Chris's Acorns (CC BY-SA 3.0).

== Related pages ==

* [[Acorn Risc PC 700]]
* [[Acorn Risc PC 600]]
* [[Acorn Risc PC 700 Maintenance Guide]]
* [[Acorn Risc PC 700 Troubleshooting Guide]]
* [[Acorn Risc PC 700 Capacitor Guide]]

== References ==

<references />

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