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ack! relevant.

RISC OS uses ARM, so the ISA is owned by ARM Ltd. Intel bought a license to produce ARM-compatible processors (well, actually they took over the license from Digital, when they bought parts of it), but they don't "own" the ISA.

Has what was Acorn always used ARM? I remember at school we used to have a tech studies room full of Acorn RISC Archimedes computers... I remember posters on the walls advertising the RISC chip as 24bit... I vaguely remember reading that intel were CISC whereas AMD was a mix of RISC/CISC architectures

So those posters would have been about ARM chips?

cheers.
Ian.

AMD use CISC now I think. I remember them using RISC internaly with a CISC interpreter in the past.

1) RISC isn't an instruction set but a concept; the ISA itself are things like SPARC, POWER, MIPS and so forth, which implement in their respective ISA's in a RISC manner.

2) AMD bought out an MIPS processor company which created embedded processor designs, IIRC the name was called Alchemy. The last time I had a check it was pretty good.

3) Intel used to sell an ARM varient called Xscale, but have since sold it off to Marvell.

4) Intel have decided that x86 is the future, they've already demonstrated a super-duper low powered chip based on the ISA which delivers lower power than traditional RISC based processors.

5) Both Intel and AMD have RISC cores internally, but then again, there is a major difference now between what the ISA is and what the microarchitecture is.

In the Past Acorn Archimedes was based on RISC processor manufactured by ARM.

http://en.wikipedia.org/wiki/Acorn_Archimedes

The actual Acorn Archimedes derivative "clone" (Iyonix) is based on Intel XScale 80321 RISC processor.

http://www.iyonix.com/

ahhh ok gotcha

Is there any real significant reason to be using this architecture today in a desktop/server computer?

I ask this as a real question rather than flamebait. I keep wishing something better than CISC and cheaper than SPARC/POWER6 comes out that I can get my hands on and so far with the Amiga/PPC I've been a bit let down with the specs:£ ratio :-|

It was 26bit if I remember correctly. Well, they were internally 32bit but had a 26bit address bus.

ack! yes it was... you just reminded me :-|

RISC was the second coming while I was at school.. nowadays the only place I see it is the ARM in my XDA and the XSCALE in my XDAII... I realise they must still make a shedload of money from embedded devices but it would be nice if they still had a decent cpu for the 'desktop'.

yeah, pretty much every portable device that doesnt have an x86 cpu shoved into them uses an ARM cpu of some form. I always had REALLY good performance out of them compared to other chips. I guess it was partly because of the OSes running on top of them as well. My Psion 5 had a 18mhz arm6, I believe, with 8mb of ram and I could run a crapload of programs on it at once with no real slowdown I miss that...

Acorn designed the ARM processor (the acronym used to be for "Acorn RISC Machine") and used it in the Archimedes and RISC PC series of desktop computers and the A4 laptop. At the time the Archimedes was launched, it was by far the most powerful home computer on the market -- it even outperformed many professional workstations. The ARM IP was spun off in a separate company (ARM Ltd.) after Apple showed interest in using it (which they did in the Newton PDA). Since the Newton required a low-power processor, development of ARM was taken in this direction rather than towards desktop use. This has been successful in the sense that nearly all PDAs and most mobile phones use ARM, but it also means that ARM can not compete against desktop processors from Intel and AMD in terms of compute power.

Since the speed increase in these has slowed down in recent years, ARM is closing in on them, though. Current dedicated RISC OS machines use rather old versions of the ARM processor, though, mainly for development cost reasons (the market is too small to support high development costs).

Thanks for the info

"Since the speed increase in these has slowed down in recent years, ARM is closing in on them, though"

Question though, 600mhz is catching up? I notice they quote 'over 1ghz' on their website. I'm sure the architecture would be nice to compare against CISC cycle per cycle... but I'm guessing the lowpower parallel configuration of these is where they really shine. Too bad I dont have the workroom to print off my own motherboard

A bit like the MIPS chips in the ye olde Sgi machines?

You know, I also just realised - the Nintendo DS is powered by both an ARM7 and an ARM9 chip... I'm kinda surprised no one has launched a RISCOS PDA considering most arms run linux or WinCE

OS9, RISCOS, BeOS, AmigaOS4 -- I think would all run pretty well on a handheld device.

Edited 2007-11-28 16:35