How was the ARM architecture born

The ARM CPU architecture is used not only in CPUs for many smartphones, but also in the M1 chip designed by Apple and Microsoft’s own chip. In addition, supercomputers equipped with ARM-based CPUs are attracting attention as they record the fastest performance in the world. How was this ARM structure developed and used in devices around the world?

Acorn Computer, a predecessor to ARM Holdings that develops ARM, was founded in Cambridge in 1978. At the time, the company developed the Acorn Atom, a home computer based on the MOS 6502 on the Apple II and Atari 2600.

In the 1980s, a project called the BBC Computer Literacy Project started in the UK to promote computer knowledge to the public. As part of this project, The Computer Program, a program that teaches computer concepts and basic programming basics, began broadcasting in 1982. The program needed a machine to process graphics and audio to describe the basic program, but there were no computers on the market that met the BBC’s requirements at the time. Therefore, the BBC asks Acorn Computer to develop a computer that meets the specifications required for the program.

Acorn Computer, which received a request from the BBC, develops BBC Micro, an educational computer using MOS 6502. At the time, BBC Micro had a great success in the UK as a very high-performance computer, and in the 1980s, it monopolized its share of domestic educational computers.

The 1980s, when BBC Micro was developed, was an important turning point in the computer industry, with IBM launching the IMB PC in 1981 and Apple launching Lisa in 1983. Acorn Computer believes that it needs a higher-performance CPU than the MOS 6502 to compete with this machine. Accordingly, in order to develop a high-performance CPU, Intel requested a development permission based on Intel 80286. But Intel ignores this request.

Acorn Computer, which has not obtained Intel cooperation, makes a decision to design its own CPU. Acorn Computer develops the RISC-based architecture ARM (Acorn Risc Machine) based on its long experience in designing MOS 6502, which has similar characteristics to RISC-based CPUs. Acorn Archimedes, a personal computer released in 1987 with a clock frequency of 8 MHz and an ARM2 with 27,000 transistors, which adopted this ARM architecture, showed higher performance than a computer with Intel 80286. From Intel’s point of view, it was a big mistake to ignore Acorn’s request for Intel 80286.

Because ARM operates with lower power and lower heat than other CPUs, it caught the eye of Apple who was developing Apple Newton at the time, and Acorn formed a business alliance with Apple. Acorn will establish Advanced RISC Machines, which will become ARM Holdings after spin-off of the ARM division. Although it cannot be said that Apple’s Newtonon was a successful product, most of the mobile terminals that require low-power and low-heat CPUs such as the iPod released in 2001 and the Nintendo DS released in 2004 have adopted ARM.

These ARMs were also adopted in the first iPhones released in 2007, and are still used in most smartphone processors, and are running on over 130 billion devices worldwide. Related information can be found here .