TABLE OF CONTENTS The Advanced RISC Machine (ARM) microprocessor is arguably the world s most popular processor for embedded applications. It can be found in applications ranging from simple street light sensors to ink-jet printers to life-critical heart monitors. The simplicity of the ARM design is an important reason for its success. A simpler processor is easy to use and frequently has faster performance. Of equal importance, a simpler processor requires less power and can therefore run from batteries. ARM has all these features and is used in many modern products, including the following:
| Cell phones | Disk drives |
| PDAs | Medical devices |
| Digital cameras | Automobile navigation systems |
| Ink and laser printers | Smart cards |
| Switches and routers | Modems |
| Wireless |
Acorn Computers Limited started development of the ARM processor in 1983. Acorn was enjoying the success of its 8-bit 6502-based microprocessor called the BBC (British Broadcasting Corporation) micro. The BBC micro was used widely in educational institutions throughout the United Kingdom. It was also a popular processor with researchers and hobbyists. However, it was an 8-bit processor, so it had many limitations. In looking for the replacement for the BBC micro, the 32-bit ARM architecture was born. The acronym ARM was formed originally from the phrase Acorn RISC Machine.
Acorn engineers evaluated many of the available processors in 1983, but those that met the functional requirements were unnecessarily complex. This undesired complexity, plus the encouraging results of the 1980 RISC (Reduced Instruction Set Computer) research at Stanford and the University of California,...
