The processor

The processor

A microprocessor is a multipurpose, programmable, clock driven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions and provides result as output. The processor (really a short form for microprocessor and also often called the CPU (Central Processing Unit) is the central component of the PC. In another sense, microprocessor is IC chip which contains ALU, memory unit which performs all related operations and control all parts. This vital component is in some way responsible for every single thing the PC does.

When the Hungrian born John Von Newmann, first suggested storing a sequence of instruction (a program) in the same memory as the data, it was a truly innovative idea. That was in his "First Draft of a Report on the EDVAC", written in 1945. The report organized the computer system into four main parts: the Central Arithmetical unit, the Central Control Unit, the Memory and the Input/ Output devices. Today, more than half a century later, nearly all processors have a Von Newmann's architecture.

Principle:

The underlying principle of all computer processors are the same. Fundamentally, they all take signals in the form of 0's and 1's(thus binary signals), manipulate them according to a set of instructions, and produce output in the form of 0's and 1's. the voltage on the line at the time a signal is sent determines whether the signal is a 0 or a 1. On a 3.3 volt system, an application of 3.3 volts means that it's a 1, while an application of 0 volts means it's a 0.

Processors work by reacting to an input of 0's and 1's in specific ways and then returning an output based on the decision. The decision itself happens in a circuit called a logic gate, each of which requires at least one transistor, with the inputs and outputs arranged differently by different operations. The fact that today's processors contain millions of transistors offers a clue as to how complex the logic system is. The processor's logic gates work together to make decisions using Boolean logic, which is based on the algebraic system established by mathematician George Boolean. The main Boolean operators are AND, OR, NOT and NAND (AND with NOT), many combinations of these are possible as well.

The flow of electricity through each gate is controlled by that gate's transistor. However, these transistors aren't individual and discrete units. Instead, large numbers of them are manufactured from a single piece of silicon (or other semiconductor material) and linked together without wires or other external materials. These units are called Integrated Circuits (ICs), and their development basically made the complexity of the microprocessor possible. The integration of circuits didn't stop with the first ICs. Just as the first ICs connected multiple transistors, multiple ICs became similarly linked, in a process known as Large-Scale Integration (LSI); eventually such sets of ICs were connected in a process called Very Large Scale Integration(VLSI).

Modern day microprocessor contain tens of millions of microscopic transistor. Used in combination with resistors, capacitors and diodes, these make up logic gates. Logic gates make up integrated circuits, and ICs make up electronic system. Intel's first claim to fame lay in its high level integration of all the processor's logic gates into a single complex processor chip. The Intel 4004 released in late 1971. This was 4-bit microprocessor, intended for use in calculator. It processed data in a 4 bits, but its instructions were 8 bits long.

According to von-Newmann, the overall computer system has input device to input data and information, central processing unit to process input data, and output devices to output the result after processing which in shown in above figure. Computer does not understand user's information directly, so we need input devices to give information to the computer to converts users information in computer understandable form. Keyboard, mouse, joystick, digital camera are the examples of input devices. Every input device has their own function e.g. the use of keyboard is to input text and character input, function of mouse is to select the options, highlight the portion of documents etc. like this, function of digital camera is to input images and photos etc.

After input the data by the user that data will go to central processing unit which is most important part, of computer. It have different parts like control unit to control all parts of computer system. ALU to perform arithmetic and logical operations, memory unit to store data etc. Arithmetic operations means calculations like addition, subtraction, multiplication, division, square root etc. in this way, logical operation means AND, OR, NOT operation. Logical operations are mainly used for decision. To perform any operation ALU receives data from memory, that memory is called register. So, after input data, data will store in memory and system performs operation for that data and gives result. The result is either stored in secondary memory or give result from output devices. All the system and operations are control by clock pulses which is generated by control unit. If the user need result or any data in future use then that data can be save in secondary memory. So, secondary memory is that type of memory which can store data without electricity. This type of memory is called non-volatile memory.

The result or output of central processing unit can not directly understand by user therefore that result should be converting to user understandable form. That function is performed by output devices like printer which gives output in the form of hard copy, monitor which gives the output in displayed form, speaker which gives output in the form of sound etc.