Digital Logic
	ä Registers are made up of and connected by digital logic circuitry ä And, or, and not gates ä Values in registers + values on pins is input, new set of values in registers + pins is output ä Clock used to activate changes in processor state ä Several clock cycles are often needed to accomplish what we think of as an instruction ä In general: ä The faster the clock the faster we can execute instructions ä The more complex the instruction the more cycles that are needed ä Some processors can execute parts of several instructions in parallel (pipeline) to increase their instructions processed per second