StrongARM

The StrongARM microprocessor is a faster version of the Advanced RISC Machines ARM design. It was created by Digital Equipment Corporation, but later sold to Intel who continues to produce it today as the XScale.

History

The StrongARM was a collaborative project between DEC and ARM to create a faster CPU based on (but not totally compatible with) the existing ARM line. The StrongARM was designed to address the upper-end of the low-power embedded market, where users needed more performance than the ARM could deliver while being able to accept more external support. Targets were devices such as newer personal digital assistants and set-top boxes.

The project was set up in 1995, and quickly delivered their first design, the SA-100. This was immediately incorporated into newer versions of the Apple Newton as well as a number of other products.

Digital Semiconductor, DEC's chip division, was later sold to Intel as part of a lawsuit settlement. Intel used the StrongARM to replace their ailing line of RISC processors, the i860 and i960. Today the design is known as the Intel XScale.

Description

The StrongARM family are faster versions of the existing ARM processors with a somewhat different instruction set. They have limited software compatibility with the "real" ARM families due to their separate caches for data and instructions, which causes self-modifying code to fail (which, admittedly, is fairly rare).

The SA-100 was the first member of the family, updated as the SA-110 and then SA-1110. The SA-1110 is the core for the XScale line, which is packaged in an innovative "stacking" system which allows various support chips to be connected together without a backplane.