Architecture

All classes of computers consist of 5 fundamental components datapath, control, memory, input, output

An instruction set architecture is a functional description (that is, abstract model) of a processor. It consists of the assembly language (instructions, registers, addressing modes), operating modes, exception handling, etc.

Each register can store 32 bits (one word). All registers live in the register file (part of the processor). Note that this is distinct from memory.

ALU operands come from registers, not memory. Load and store instructions move data between registers and memory.

In this way, registers are more "temporary" than memory. In order to operate on two numbers from memory, we would have to load them both into different registers.