Acorn pulled out of making desktop computers in 1998, when it cancelled the Risc PC 2, the Acorn Phoebe.
The machine was complete, but the software wasn't. It was finished and released as RISC OS 4, an upgrade for existing Acorn machines, by RISC OS Ltd.
by that era, ARM had lost the desktop performance battle. If Acorn had switched to laptops by then, I think it could have remained competitive for some years longer -- 486-era PC laptops were pretty dreadful. But the Phoebe shows that what Acorn was actually trying to build was a next-generation powerful desktop workstation.
Tragically, I must concede that they were right to cancel it. If there had been a default version with 2 CPUs, upgradable to 4, and that were followed with 6- and 8-core models, they might have made it, but RISC OS couldn't do that, and Acorn didn't have the resources to rewrite RISC OS to do it. A dedicated Linux machine in 1998 would have been suicidal -- Linux didn't even have a FOSS desktop in those days. If you wanted a desktop Unix workstation, you still bought a Sun or the like.
(I wish I'd bought one of the ATX cases when they were on the market.)
Castle Technology continued with new desktop machines -- the Iyonix and others -- but they never made sense in bang-for-the-buck terms. I'd have loved a slim light RISC OS laptop, though.
An idea occurs I've never had before: 1998, when the Phoebe was cancelled, is the same year that Be ported BeOS to x86. A multi-processor Acorn machine running ARM BeOS would have been a stunning machine at the time -- what BeOS did on limited hardware, without acceleration, was superb. I'm surprised this has never struck me before.
Acorn hardware with Be software would have been a gorgeous combination, and would have offered a fairly compelling proposition for the time. As radical in terms of "power without the price" as the Atari ST was a decade before.
But looking at the bigger picture -- the rising ascendance of Windows NT, by that time a decent credible OS; Apple's provident acquisition of NeXT; and the fact that Linux was getting serious, with Kernel 2.0, proper SMP support, and KDE 1.0 coming out that year -- no, whereas there might have been a flurry of interest, it would probably have been dead within a few years.
So no, the Phoebe could not have competed. The 200MHz StrongARM wasn't massively quicker than the Intel Pentium 90, as the Pentium was a superscalar chip.
But it was cheap and it didn't put out a lot of heat.
Before Acorn launched the StrongARM upgrade for the RISC PC, another company, Simtec, offered a multiprocessing add-on, the Hydra. It allowed a Risc PC to have 4 additional ARM processor daughterboards in its second processor slot.
Symmetric multiprocessing -- SMP -- was niche at first but it was blatantly obvious for years that this was the coming thing. But in the late '90s, CPUs were becoming a significant part of system cost, and heat dissipation was becoming an issue. I saw machines failing when their cooling systems failed, or you even left the lid off.
There was a niche for Acorn to aim at, but it didn't, because it was committed to RISC OS. However, the foundations of that OS were not sound. Same as classic MacOS, same as Win9x.
Apple fooled around for far too long before acquiring NeXT and doing a remarkable big-bang approach rip-and-replace OS upgrade. I'm amazed it worked, but boy, did it ever work well for them. The dev tools, the design and leadership genius of Steve Jobs, and some great hardware were part of it too, of course.
Microsoft made the best of the OS/2 debacle and Portable OS/2 codebase, hired Dave Cutler, and in a magnificent achievement of avoiding the Osborne effect, managed to nurse the whole damned PC industry along on Win9x until NT was ready for prime-time.
Acorn didn't, stuck with its decrepit old last-minute hack of an OS, and then gave up. Its stub remnant of ARM did extraordinarily well, though.
Commodore and Atari didn't, and died, too. If Commodore had executed better on either its Taos/Intent or its QNX plans, it might have made it.
But they didn't, and we're perilously close to a monoculture now as a result.
I have an Amiga (and a Mac Mini G4 with MorphOS), I have an ST, I have a QL. I recently sold my BlackBerry, my only QNX device. I've played with them all, but I didn't know them well and I didn't love AmigaOS or GEM or QDOS or any of them.
The ones I used a lot and really did love were Psion's EPOC16 and EPOC32, classic MacOS and RISC OS 2. (By RISC OS 3 and later releases, I'd moved on.)
But while I loved the elegance of the GUIs of both RISC OS and MacOS 6/7/8/9, they were always terribly unstable and had deep problems caused by poor, or at least dated, design.
But there is precedent, remarkably, for making and selling SMP computers even if your OS doesn't support it. The Macs went SMP in '95 (!) with the Daystar Genesis MP and later Apple's own PowerMac 9600.
Classic MacOS didn't support the extra CPUs. Only PhotoShop did at first. That was enough to sell some kit, even at over $7,000.
I said back then that Acorn should do it. Of course, nobody listened.
Only Acorn could have sold multiprocessor machines which were not significantly more costly than uniprocessor ones, because in Acorn kit, the CPU was cheap and didn't require any cooling. These were plastic-packaged chips. Not even heatsinks. They could have shipped a dual-CPU machine for under £50 more than a uniprocessor one, I reckon. Nobody else could have touched that.
The big problem is that Acorn was committed to RISC OS by then, and RISC OS was and is resolutely a single-core, single-tasking OS with a cooperative-multitasking GUI on top -- a little like Windows 3 on MS-DOS. Acorn had already discontinued its Unix, RISC iX, in 1992.
Linux wasn't ready to be a mainstream desktop SMP OS yet at the end of the 1990s -- the first version to support SMP, kernel 2.0, came out in 1996 and I'm told it only usefully supported 2 processors. KDE 1.0 wouldn't ship until 1998.
So what OS would this hypothetical SMP Acorn workstation have run?
Well, it occurs to me now, that there was an ideal candidate. BeOS.
Some, sadly, are what not to do.
For instance, it switched platforms 3, arguably 4 or 5 times, and that stopped it acquiring any momentum.
It started off with dual AT&T Hobbit CPUs in the prototype BeBox hardware (circa 1993). Be (sensibly) switched the BeBox to dual PowerPC CPUs before release (1995).
BeOS was fast, elegant, attractively GUI-centric. It was stable, it had superb media support without fancy hardware acceleration -- just the sort of kit Acorn made.
Now, true, it would have looked radically unfamiliar to RISC OS users, but I'm sure they could have built bridges. A RISC OS VM for BeOS, and a port of BBC BASIC, as a minimal starter.
BeOS needed its own great hardware, so instead of running on PowerMacs, it switched to Intel. Acorn had great hardware, but it needed an OS.
It never happened, but perhaps it should have.