Define in detail about the Architecture

Architecture is the set of resources visible to machine language programmer: Registers, the memory, data representations, instructions formats, addressing modes, I/O controllers, control states, interrupts etc. Even though often the architecture is thought to be equivalent to machine language set of a computer, it is more than that. Still, a major portion of architecture coverage is devoted the machine language set. A related issue in past was whether the machine language set must be complex (complex instruction set computer, CISC) or simple (reduced instruction set computer, RISC).