<processor> (RISC) A processor whose design is based on the
rapid execution of a sequence of simple instructions rather
than on the provision of a large variety of complex
instructions (as in a Complex Instruction Set Computer).
Features which are generally found in RISC designs are uniform
instruction encoding (e.g. the op-code is always in the same
bit positions in each instruction which is always one word
long), which allows faster decoding; a homogenous register
set, allowing any register to be used in any context and
simplifying compiler design; and simple addressing modes
with more complex modes replaced by sequences of simple
arithmetic instructions.
Examples of (more or less) RISC processors are the Berkeley
RISC, HP-PA, Clipper, i960, AMD 29000, MIPS R2000
and DEC Alpha. IBM's first RISC computer was the RT/PC
(IBM 801), they now produce the RISC-based RISC
System/6000 and SP/2 lines.
Despite Apple Computer's bogus claims for their
PowerPC-based Macintoshes, the first RISC processor used
in a personal computer was the Advanced RISC Machine (ARM)
used in the Acorn Archimedes.
