Computing & Telecommunications

Steve Furber and Sophie Wilson, The ARM processor

After studying mathematics and computer science at Cambridge University, Sophie Wilson joined Acorn Computers in 1979. Steve Furber earned a B.A. in mathematics and a Ph.D. in aerodynamics from the University of Cambridge and became an employee of Acorn in 1981. Both had worked for Acorn part time since it was founded.

Wilson and Furber led the development of the BBC Micro, creating the operating system and BBC BASIC, designing the hardware, and managing all the people and documentation involved. By the end of its life cycle in 1989, the BBC Micro was used in thousands of schools and more than 1 million units were sold, far beyond the sales goal of 12,000.

In 1983, Wilson designed the instruction set for one of the first RISC processors, called the Acorn RISC Machine or ARM. RISC or reduced instruction set computing means a microprocessor chip that uses a reduced and limited set of simple instructions rather than the more complex set of instructions that until then caused most chips to run more slowly than desired.

Once Wilson completed the basic work on the instruction sets, it was up to Furber to turn Wilson’s design into something that could be implemented and manufactured. It took Wilson, Furber and their team about 18 months and 10-12 person-years of work to go from idea to usable chip.

When they first tested the chip, however, the team was puzzled. The device seemed to be using no electrical power whatsoever according to a multimeter. It turned out that the board had a fault and there was no current being sent to the power supply line. The processor was running on electricity that was leaking from the input/output connections.

The ARM chip was not designed to be a low power device, simply to be inexpensive. But its low power consumption turned out to be of extreme importance years later and became one of its biggest selling points. Though ARM chips sold well for a few years, it was not until computing devices got radically smaller with the appearance of MP3 music players, smart phones and tablet computers that low power consumption became a chief selling point for microprocessors.

Today, ARM chips dominate the processor chips inside smart phones, digital cameras and other mobile devices. They can be found in the Apple iPhone and Samsung Galaxy, for example. ARM shipments to date exceed 40 billion units and the company says they are at the heart of more than 35% of all consumer devices worldwide. ARM’s goal is to have its processors in more than half of all tablets, mini-notebooks and other mobile PCs sold by 2015.

Unlike other semiconductor companies, ARM Holdings does not manufacture its own chips. ARM licenses its intellectual property and companies such as Qualcomm, Apple, Intel, Samsung, and Texas Instruments make processors based on its designs. ARM now has 973 licensees and signed 22 new ones in the first quarter of 2013. Shipment of ARM chips are running at about 10 billion a year, up 35% from a year ago.

Furber today is ICL professor of computer engineering at the University of Manchester. Wilson is senior technical director in Broadcom’s Cambridge, UK office.


Steve Furber and Sophie Wilson, The ARM processor

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