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The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in embedded designs. Because of their power saving features, ARM CPUs are dominant in the mobile electronics market, where low power consumption is a critical design goal. Today, the ARM family accounts for approximately 75% of all embedded 32-bit RISC CPUs, making it one of the most widely used 32-bit architectures. ARM CPUs are found in most corners of consumer electronics, from portable devices (PDAs, mobile phones, media players, handheld gaming units, and calculators) to computer peripherals (hard drives, desktop routers); however it no longer has significant penetration as the main processor in the desktop computer market and has never been used in a supercomputer or cluster. Important branches in this family include Marvell's XScale and the Texas Instruments OMAP series.
|Contents | |[hide] | |1 History | |2 ARM cores | |3 Design notes | |3.1 Thumb | |3.2 DSP Enhancement Instructions | |3.3 Jazelle | |3.3.1 Implementation | |3.3.2 Instruction set | |3.3.3 Application binary interface (ABI) | |22.214.171.124 CPSR: Mode indication | |126.96.36.199 BXJ: Branch to Java | |188.8.131.52 Low-level registers | |3.4 Thumb-2 | |3.5 Thumb Execution Environment (ThumbEE) | |3.6 Advanced SIMD (NEON) | |3.7 VFP | |3.8 Security Extensions (TrustZone) | |4 ARM licensees | |4.1 Approximate licensing costs | |5 References | |6 See also | |7 External links |
A Conexant ARM processor used mainly in routers
The ARM design was started in 1983 as a development project at Acorn Computers Ltd to build a compact RISC CPU. Led by Sophie Wilson and Steve Furber, a key design goal was achieving low-latency input/output (interrupt) handling like the MOS Technology 6502 used in Acorn's existing computer designs. The 6502's memory access architecture allowed developers to produce fast machines without the use of costly direct memory access hardware. The team completed development samples called ARM1 by April 1985, and the first "real" production systems as ARM2 the following year. The ARM2 featured...