WHAT IS ARM?
ARM (previously an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computing (RISC) architectures for computer processors, configured for various environments. Arm Ltd. develops the architecture and licenses it to other companies, who design their own products that implement one of those architectures.
WHEN HAS IT EMERGED?
Acorn Computers' first widely successful design was the BBC Micro, introduced in December 1981. This was a relatively conventional machine based on the MOS 6502 CPU but ran at roughly double the performance of competing designs like the Apple II due to its use of faster DRAM. Typical DRAM of the era ran at about 2 MHz; Acorn arranged a deal with Hitachi for a supply of faster 4 MHz parts.1981 was also the year that the IBM PC was introduced. Using the recently introduced Intel 8088, a 16-bit CPU compared to the 6502's 8-bit design, it was able to offer higher overall performance. Acorn began considering how to compete in this market and produced a new paper design known as the Acorn Business Computer. They set themselves the goal of producing a machine with ten times the performance of the BBC Micro, but at the same price point. This would outperform and underprice the PC. At the same time, the recent introduction of the Apple Lisa brought the Xerox Star's concept to a wider audience and suggested the future belonged to machines with a graphical user interface. The Lisa, however, cost $9,995, as it was packed with support chips, large amounts of memory and a hard drive, all very expensive at that time. Two key events led Acorn down the path to ARM. One was the publication of a series of reports from the University of California, Berkeley, which suggested that a simple chip design could nevertheless have extremely high performance, much higher than the latest 32-bit designs on the market. The second was a visit by Steve Furber and Sophie Wilson to the Western Design Center, a company run by Bill Mensch and his sister, which had become the logical successor to the MOS team and was offering new versions like the WDC 65C02. The Acorn team saw high school students producing chip layouts on Apple II machines, which suggested that anyone could do it. In contrast, a visit to another design firm working on modern 32-bit CPU revealed a team with over a dozen members which were already on revision H of their design and yet it still contained bugs. This cemented their late 1983 decision to begin their own CPU design, the Acorn RISC Machine. The first samples of ARM silicon worked properly when first received and tested on 26 April 1985.Known as ARM1, these versions ran at 6 MHz. The first ARM application was as a second processor for the BBC Micro, where it helped in developing simulation software to finish development of the support chips (VIDC, IOC, MEMC), and sped up the CAD software used in ARM2 development.
The result of the simulations on the ARM1 boards led to the late 1986 introduction of the ARM2 design running at 8 MHz, and the early 1987 speed-bumped version at 10 to 12 MHz. In the late 1980s, Apple Computer and VLSI Technology 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, Arm Holdings plc, floated on the London Stock Exchange and NASDAQ in 1998. Apple used the ARM6-based ARM610 as the basis for their Apple Newton PDA.
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