Arithmetic Logic Unit
Terms in this set (5)
addition and subtraction
these two tasks are performed by constructs of logic gates, such as half adders and full adders. while they may be termed 'adders' with the aid of they can also perform subtraction via use of inverters and twos complement arithmetic.
multiplication and division
in most modern processors, the multiplication and division of integer values is handled by specific floating point hardware within the CPU. earlier processors used either additional chips known as maths co processors, or used a completely different method to perform the task.
further logic gates are used within the ALU to perform a number of different logical tests, including seeing if an operation produces a result of zero. most of these logical tests are used to then change the values stored in the flag register
comparison operations compare values in order to determine such things as whether one number is greater than, less than or equal to another.
shifting operations move bits left or right within a word, within different operations filling the gaps created in different ways. this is accomplished via the use of the shift register which uses pulses from the clock within the control unit to trigger a chain reaction of movement across the bits that make up a word.