Computer Architecture is the field of study of selecting and
interconnecting hardware components to create computers that satisfy
functional performance and cost goals. It refers to those
attributes of the computer system that are visible to a programmer
and have a direct effect on the execution of a program.
Computer Architecture concerns Machine Organization, interfaces,
application, technology, measurement & simulation that Includes:
- Instruction set
- Data formats
- Principle of Operation (formal description of every operation)
- Features (organization of programmable storage, registers used,
interrupts mechanism, etc.)
In short, it is the combination of Instruction Set Architecture, Machine
Organization and the related hardware.