Feeds

ARM creators Sophie Wilson and Steve Furber

Part Two: the accidental chip

5 things you didn’t know about cloud backup

Call to ARMs

The first ARM used 25,000 transistors. "It was a really small, simple piece of design," says Furber.

Today one of the most significant features of the ARM family is its low power consumption. But that hadn't been an initial goal, according to Furber. “We designed the ARM for an Acorn desktop product, where power isn't of primary importance. But it had to be cheap. Cheap meant it had to go in a plastic package, plastic packages have a fairly high thermal resistance, so we had to bring it in under 1W.”

The orginal ARM chip at 3µm

The original 3µm ARM chip

The power test tools they were using were unreliable and approximate, but good enough to ensure this rule of thumb power requirement. When the first test chips came back from the lab on the 26 April 1985, Furber plugged one into a development board, and was happy to see it working perfectly first time.

Deeply puzzling, though, was the reading on the multimeter connected in series with the power supply. The needle was at zero: the processor seemed to be consuming no power whatsoever.

As Wilson tells it: “The development board plugged the chip into had a fault: there was no current being sent down the power supply lines at all. The processor was actually running on leakage from the logic circuits. So the low-power big thing that the ARM is most valued for today, the reason that it's on all your mobile phones, was a complete accident."

Wilson had, it turned out, designed a powerful 32-bit processor that consumed no more than a tenth of a Watt.

Steve Furber's ARM SoC Architecture

From the horse's mouth...

“Running on leakage” also happened to be an appropriate description of Acorn outside the lab. To staunch the haemorrhaging finances, Italian computer manufacturer Olivetti stepped in with an initial cash injection in February 1985. By the end of the year, Olivetti had taken a controlling interest, effectively buying the company.

“Olivetti wasn't told about the ARM when they bought Acorn,” Steve Furber remembers. When they found out, he says, “they didn't know what to do with it”. Wilson and Furber did, and were able to push through the ARM’s initial commercial appearance in the ARM Development System, a specialist add-on to BBC Micro costing £4500.

The essential guide to IT transformation

More from The Register

next story
So, Apple won't sell cheap kit? Prepare the iOS garden wall WRECKING BALL
It can throw the low cost race if it looks to the cloud
Samsung Gear S: Quick, LAUNCH IT – before Apple straps on iWatch
Full specs for wrist-mounted device here ... but who'll buy it?
Apple promises to lift Curse of the Drained iPhone 5 Battery
Have you tried turning it off and...? Never mind, here's a replacement
Now that's FIRE WIRE: HP recalls 6 MILLION burn-risk laptop cables
Right in the middle of Burning Mains Man week
HUGE iPAD? Maybe. HUGE ADVERTS? That's for SURE
Noo! Hand not big enough! Don't look at meee!
AMD unveils 'single purpose' graphics card for PC gamers and NO ONE else
Chip maker claims the Radeon R9 285 is 'best in its class'
prev story

Whitepapers

Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Advanced data protection for your virtualized environments
Find a natural fit for optimizing protection for the often resource-constrained data protection process found in virtual environments.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Next gen security for virtualised datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.