instruction set architecture definition architecture
(ISA) The parts of a processor
's design that need to be understood in order to write assembly language
, such as the machine language
instructions and registers
. Parts of the architecture that are left to the implementation, such as number of superscalar
functional units, cache
size and cycle
speed, are not part of the ISA.
The definition of SPARC
, for example, carefully distinguishes between an implementation and a specification.