<P> The arithmetic logic unit (ALU) is a digital circuit within the processor that performs integer arithmetic and bitwise logic operations . The inputs to the ALU are the data words to be operated on (called operands), status information from previous operations, and a code from the control unit indicating which operation to perform . Depending on the instruction being executed, the operands may come from internal CPU registers or external memory, or they may be constants generated by the ALU itself . </P> <P> When all input signals have settled and propagated through the ALU circuitry, the result of the performed operation appears at the ALU's outputs . The result consists of both a data word, which may be stored in a register or memory, and status information that is typically stored in a special, internal CPU register reserved for this purpose . </P> <P> Most high - end microprocessors (in desktop, laptop, server computers) have a memory management unit, translating logical addresses into physical RAM addresses, providing memory protection and paging abilities, useful for virtual memory . Simpler processors, especially microcontrollers, usually don't include an MMU . </P> <P> Most CPUs are synchronous circuits, which means they employ a clock signal to pace their sequential operations . The clock signal is produced by an external oscillator circuit that generates a consistent number of pulses each second in the form of a periodic square wave . The frequency of the clock pulses determines the rate at which a CPU executes instructions and, consequently, the faster the clock, the more instructions the CPU will execute each second . </P>

A very fast type of memory that is found within the processor