It is a cycle of input, processing and output. We input the data we have collected, then process it. When the data has been processed, some data is output. In response to the data output we may wish to respond by inputting further data in reply. This is in turn processed and the cycle continues until we have no further data to input.
The data processing cycle may be based on a computer shown below:
A present day computer has four components: Input unit, memory, central Processing Unit( CPU) and output unit. A brief Discussion of each component is given below:
1. Input unit
2. Memory unit
3. CPU (Central processing unit)
4. Output unit.
1.Input Unit:
An input device reads the data & program into the computer. The program contains instruction about what has to be done with the data. Some popular input devices are mouse, keyboard, joystick, scanner etc.
2.Memory Unit:
This part of the computer is used as storage of program as well as data. The memory can be both internal & external depending upon its location in the computer system. The internal memory generally known as primary memory or main memory is directly accessible to the CPU and volatile in nature. The external memory, generally known as secondary storage, includes magnetic storage devices such as hard disk, magnetic drums etc. The secondary memory is not directly accessible to the CPU and non- volatile in nature. It may be noted that the secondary storage can be accessed to the CPU through input/output controllers.
3.CPU (Central Processing Unit):
The purpose of a CPU is to process data and programs stored in the main memory. It performs arithmetic & logical operations in addition to control & supervision of the entire computer system. The CPU is in fact the heart of the computer.
The purpose of CPU is to execute the programs stored in the main memory by performing the following tasks:
1.Fetch instruction from memory
2.Undrestand the fetched instruction to determine what is needed.
3.Perform arithmetic or logical operation as data
4.Write data, if required, either to a memory location or an output device.
The main components of CPU are : CU (control unit), ALU (arithmetic & logical unit) & set of registers.
Arithmetic & Logical Unit (ALU):
The control unit is responsible for the movement of data & instructions in & out of the memory and CPU. This unit provides the facility to perform arithmetic & logical operation such as addition, subtraction, multiplication, comparison etc. The operators used by ALU are as follows:
Arithmetic Operation Logical Operation
+ Add =, != equal to, not equal to
- Subtraction > greater than
* Multiply < less than
/ Divide >= greater than equal to
^ Raised by a power <= less than equal to
Control Unit:
The control unit is responsible for the movement of data & instructions in & out of the memory & CPU. The basic responsibility of a CPU is to control I/O operations, guide the routing of the data between the memory and ALU and govern the interval operations of CPU.
The control unit tells the ALU where the data to be processed, what operation to perform, where in the memory that the results are to be stored. These successive command flows in the form of control signals along the control lines to the various components of the computer system.
Registers:
The set of registers is a set of temporary memory locations in the CPU & each register has specific function. These memory elements are capable of receiving information, holding it & transferring it very quickly. They are used as temporary memory locations in the sense that the information or data is held in them only for as long as it is necessary for one instruction. Registers can be of different sizes & capacities.
4.Output Unit:
This unit delivers the obtained results into the output devices. Some important output devices are monitor, printer, speaker box etc.
Exercise 1
Self-test
1. The term _____________________is used to describe a processing device made up of electronic and electromechanical parts.
2. Basic resources of human beings are _____________ ,_____________,_____________.
3. Computer system is a combination of _________ and software.
4. The four main components of a computer are : Input Unit, __________.__________ and________.
5. The purpose of CPU is to _____________ the programs stored in the _____________ memory.
6. Data processing system transforms data into_______________.
7. The sub units of CPU are: ALU, _____________ and___________.
8. Calculations are made in computer with the help of its_______(Memory/ALU/CU)
Short-Answer Questions
1. What is computer?
1. Differentiate data, information and knowledge.
2. What are the basic components and functions of a computer system?
3. What is a CPU? What are three sub units of CPU? Explain the functions of each unit.
4. What is the purpose of main memory in a computer system.
5. List out three input and three output devices.
6. Distinguish between primary and secondary memory.
7. What role does the input unit play in a computer.
Long- Answer Questions
1. Explain data, Information and knowledge with examples.
2. What is computer? Explain its basic architecture along with the functioning of each units.
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