u And Its Working Principle 3d3u3f

Central Processing Unit (U) Information Technology

U • A computer does mainly four functions: – Receive input: through various input device – Process Information: Perform arithmetic or logical operations on the information – Produce output: thru output device – Store Information: storage device

• Computer hardware falls into two categories – Processing hardware: Central Processing Unit, where data processing is done – Peripheral devices: interact with the U

Central Processing Unit (U) • The part of the computer that executes program instructions is known as the processor or central processing unit(U). • The central processing unit consists of three main components, the control unit, the arithmetic unit(ALU), and the s. The U has two parts- the control unit and the arithmetic logic unit.

Control Unit • It directs the movement of electronic signals between memory(which temporarily holds data, instructions and processed information) and the ALU. It also directs these control signals between the U and input/output devices. • Each instruction in the instruction set is expressed in microcode – a series of basic directions that tells the U how to execute more complex operations. Microcode is the lowest-level instructions that directly control a microprocessor.

Arithmetic Logic Unit • Performs two types of operationsarithmetic and logical. Arithmetic operations are the fundamental mathematical operations consisting of addition, subtraction, multiplication and division. Logical operation consist of comparisons. • Many instructions carried out in the control unit involve moving data from one place to another- from memory to storage device, from memory to the printer or monitor and so on.

Arithmetic Logic Unit •

Operations Performed by the ALU Arithmetic Logical Operations The ALU Addition Equal to includes a Subtraction Not equal to group of high Multiplication Greater than; not speed greater thannot less Division Less than; memory than Exponentiation Greater than or equalthan to; not greater locations(Re Less or equal than or equal to less or equal to; not gister) built than or equal to

directly into the U, which are used to hold data that is

s U and Memory

Workspace ALU Does all the computing

ROM

Control Unit Controls & checks RAM

• are a number of small, highspeed memory units. • They hold the material that the U is currently working with and they can be thought of as being the U’s workspace. • The ALU works on the data held in the s acting on the instructions which are also held there.

Machine Cycle • Every time the U executes an instruction, it takes a series of steps called the machine cycle. The machine cycle consists of two subcycles- the instruction cycle and the execution cycle. The machine four steps -- fetching, decoding, executing and storing. The first two forms the instruction cycle and the last two forms the execution cycle.

Machine Cycle 1.Fetching: fetches the instruction from the memory 2.Decoding: breakdown or decode the command 3.Executing: execute the command, U carries out the instruction in order by converting them into microcode. 4.Storing: The U may be required to store the results in the memory.

Working of U and Memory • Page 90 and 91 (write 15 steps and draw the diagram)