Instruction/Binary Instruction/Machine Instruction/Native Instruction: a sequence of bits understood by the processor to signal a certain action.
Different CPU’s recognize different instructions, but all CPU’s need instructions to do a few basic things:
- copy bits
- arithmetic
- bit logic
- jumps (including a conditional jump)
Register: a small memory area in a processor. Modern CPU’s tend to have between a few dozen and a few hundred registers, each usually 32 to 128 bits in size.
ISA (Instruction Set Architecture): the set of instructions and registers of a CPU. When two processors implement the same ISA, they can both run the same machine code. The most prevelant ISA today is x86, used in Intel and AMD processors in PC’s. ISA’s tend to evolve over time such that later processors extend the set of registers and instructions. So today’s x86 processors can run code which older x86 processors cannot.
