KEEP IT SIMPLE

The Central Processing Unit (CPU) or the processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions.

In the early days of the computer industry, programming was done in assembly language or machine code, which encouraged powerful and easy to use instructions. CPU designers tried to make instructions that would do as much work as possible.

For example, the original IBM PC processor, Intel 8088, had a highly complex instruction set with many instructions and addressing modes. In the Seventies a new “do-less” design strategy started to gain more and more popularity: instructions which did less might still provide high performances if this simplicity could be used to make instructions execute very quickly. The Reduced Instruction Set Computer (RISC) philosophy was to minimize the number of instructions by using a scheme called a compiler, which was designed to work very fast with just a few simple instructions.

In October 1983, Acorn Computers Ltd started its RISC Machine project. Furber was the principal designer of the new microprocessor for their next personal computer. The team completed development samples called ARM1 in 1985, and finished the first production systems, ARM2 the following year. ARM1 was the world’s first commercially available RISC microprocessor, and possibly the simplest useful processor in the world, with only 25,000 transistors. This simplicity led to its excellent low-power needs, and yet it performed better than the Intel 286 processor used in the IBM PC.

Reducing the number of different instructions that a microprocessor can execute means it can execute them more quickly. The processor will be a lot simpler, cheaper to make and will use less power. These are the features which have made ARM chips so popular. They give the most processing power possible for a given amount of electricity. Thanks to a fundamentally simple and elegant design, ARM processors contain fewer components than the alternative solutions to getting the job done.