variable. from the perspective of assemble laguage， variable is a register of memory corresponding to some address
pointer. pointer is a address variable
combinational circuits. combinational circuits's out is only related to input . ALU
sequential circuits. sequential circuits's output is not only related to the input, but also related to the output of the last clock。register counter
every line of assemble language is corresponding to a machine code. machine code is corresponding to the perspective of Computer, character and symbol(String) corresponding to the perspective of our human. symbolic programming. symbolic abstraction.