Relation to instruction set architecture Microarchitecture

a microarchitecture organized around single bus

the isa same programming model of processor seen assembly language programmer or compiler writer. isa includes execution model, processor registers, address , data formats among other things. microarchitecture includes constituent parts of processor , how these interconnect , interoperate implement isa.

the microarchitecture of machine represented (more or less detailed) diagrams describe interconnections of various microarchitectural elements of machine, may single gates , registers, complete arithmetic logic units (alus) , larger elements. these diagrams separate datapath (where data placed) , control path (which can said steer data).

the person designing system draws specific microarchitecture kind of data flow diagram. block diagram, microarchitecture diagram shows microarchitectural elements such arithmetic , logic unit , register file single schematic symbol. typically, diagram connects elements arrows, thick lines , thin lines distinguish between three-state buses (which require three-state buffer each device drives bus), unidirectional buses (always driven single source, such way address bus on simpler computers driven memory address register), , individual control lines. simple computers have single data bus organization – have single three-state bus. diagram of more complex computers shows multiple three-state buses, machine more operations simultaneously.

each microarchitectural element in turn represented schematic describing interconnections of logic gates used implement it. each logic gate in turn represented circuit diagram describing connections of transistors used implement in particular logic family. machines different microarchitectures may have same instruction set architecture, , capable of executing same programs. new microarchitectures and/or circuitry solutions, along advances in semiconductor manufacturing, allows newer generations of processors achieve higher performance while using same isa.

in principle, single microarchitecture execute several different isas minor changes microcode.