ARM

ARM, previously Advanced RISC Machine, originally Acorn RISC Machine, is a family of RISC for computer processors, configured for various environments. (formerly ) develops the architecture and licenses it to other companies, who design their own products that implement one of those architectures—including s (SoC) and s (SoM) that incorporate memory, interfaces, radios, etc. It also designs that implement this  and licenses these designs to a number of companies that incorporate those core designs into their own products.

Background
Processors that have a RISC architecture typically require fewer s than those with a (CISC) architecture (such as the x86 processors found in most personal computers), which improves cost, power consumption, and heat dissipation. These characteristics are desirable for light, portable, battery-powered devices—including s, s and s, and other s —but are also useful for s and  to some degree. For s, which consume large amounts of electricity, ARM is also a power-efficient solution.

With over 130 billion ARM processors produced,    As of 2019, ARM is the most widely used  (ISA) and the ISA produced in the largest quantity. Currently, the widely used Cortex s, older "classic" cores, and specialized variants are available for each of these to include or exclude optional capabilities.

Market competition
Arm's main CPU competitors in servers include IBM, Intel and AMD. Intel competed with Arm-based chips in mobile, but Arm no longer has any competition in that space (however, vendors of actual Arm-based chips compete within that space). Arm's main GPU competitors include mobile GPUs from American and Japanese technology companies,  , and increasingly Nvidia and Intel. Despite competing within GPUs, Qualcomm and Nvidia have combined their GPUs with Arm-licensed CPUs.

Ownership
Arm had a primary listing on the and was a constituent of the. It also had a secondary listing on. However Japanese telecommunications company made an agreed offer for Arm on 18 July 2016, subject to approval by Arm's shareholders, valuing the company at £24.3 billion. The transaction was completed on 5 September 2016.

On 13 September 2020, it was announced that Nvidia would buy Arm from SoftBank for $40 billion, subject to regulatory approval, with the latter acquiring a 10% share in Nvidia. In December 2021, the filed a lawsuit to block the deal, claiming that Nvidia's ownership of  could stifle innovation and competition in the processor market.

Apple and ARM
In the late 1980s, Apple Computer and started working with Acorn on newer versions of the ARM core. In 1990, Acorn spun off the design team into a new company named Advanced RISC Machines Ltd., which became ARM Ltd when its parent company,  plc, was floated on the  and  in 1998. Apple invested 3 million for a 30% stake in the venture. The new Apple-ARM work would eventually evolve into the ARM6, first released in early 1992. Apple used the ARM6-based ARM610 as the basis for their Newton PDA. However, with disappointing sales, Apple closed down the Newton Systems Group in 1998 and sold its stake in ARM for $800 million in desperately needed cash.

In 2001, Apple released the first iPod, which used a ARM-based processor from PortalPlayer and ran an operating system designed by Pixo, which was co-founded and staffed by former Newton employees.

Apple licensed ARM technology for the A4, A5, and A5X and other early processors used in its iPhone and iPad lines. However, Apple acquired P.A. Semi for $278 million in April 2008 to bring in-house to the company. The Apple A6 contained a custom CPU designed internally at Apple (called "Swift") instead of one licensed from ARM.