A computer is an electronic device that can be programmed to accept data (input), process it and generate result (output). A computer system primarily comprises a central processing unit (CPU), memory, input/output devices and storage devices. All these components function together as a single unit to deliver the desired output.
Central Processing Unit (CPU):-
It is commonly called processor also. The CPU fetches the program and data from the memory and performs arithmetic and logic operations as per the given instructions and stores the result back to memory.
Arithmetic Logic Unit (ALU):-
Performs all the arithmetic and logic operations that need to be done as per the instruction in a program.
Control Unit (CU):-
Controls sequential instruction execution, interprets instructions and guides data flow through the computer’s memory, ALU and input or output devices.
Input Devices
The devices through which control signals are sent to a computer are termed as input devices. These devices convert the input data into a digital form that is acceptable by the computer system.
Some examples of input devices include keyboard, mouse, scanner, touch screen, etc.,
Output Devices
The device that receives data from a computer system for display,, is called output device. It converts digital information into human understandable form. For example, monitor, projector, headphone, speaker, printer, etc.
Evolution of Computer
Abacus(500 BC):-
It was a mechanical device capable of doing simple arithmetic calculations only.
Pascaline(1642):-
Blaize Pascal invented a mechanical calculator known as Pascaline to do addition and subtraction of two numbers directly and multiplication and division through repeated addition and subtraction.
Analytic Engine(1834):-
Charles Babbage invented analytical engine, a mechanical computing device for inputting, processing, storing and displaying the output.
Tabulating Machine(1890):-
Herman Hollerith designed it for summarising the data stored on the punched card.
Turing Machine(1937):-
Was a general purpose programmable machine.
EDVAC/ENIAC(1945):-
Computers was introduced by John Von Neumann based on the concept of stored program computer
Transistor(1947):-
Vacuum tubes were replaced by transistors
Integrated Circuit (1970):-
An Integrated Circuit (IC) is a silicon chip which contains entire electronic circuit on a very small area.
Computer Memory
A computer system needs memory to store the data and instructions for processing.
Units of Memory
A computer system uses binary numbers to store and process data. The binary digits 0 and 1, which are the basic units of memory, are called bits.
A 4-bit word is called a Nibble. Examples of nibble are 1001, 1010 etc
8-bit word is called a byte, for example, 01000110
Types of Memory
Computers have two types of memory — primary and secondary.
Primary Memory
- Primary memory is an essential component of a computer system. Program and data are loaded into the primary memory before processing.
- The CPU interacts directly with the primary memory to perform read or write operation.
- It is of two types viz. (i) Random Access Memory (RAM) and (ii) Read Only Memory (ROM).
Secondary Memory/auxiliary memory
- It store data permanently for future use.
- The secondary memory is non-volatile.
- It has larger storage capacity than primary memory.
- It is slower and cheaper than the main memory.
Cache Memory:-
To speed up the operations of the CPU, a very high speed memory is placed between the CPU and the primary memory known as cache memory.
Data Transfer between Memory and CPU
- Data need to be transferred between the CPU and primary memory as well as between the primary and secondary memory.
- Data are transferred between different components of a computer system using physical wires called bus.
Bus is of three types —
- Data bus to transfer data between different components
- Address bus to transfer addresses between CPU and main memory.
- Control bus to communicate control signals between different components of a computer. All these three buses collectively make the system bus.
Microprocessor :-
A microprocessor is a small-sized electronic component inside a computer that performs basic arithmetic and logical operations on data. Microprocessors are classified on the basis of different features which include chip type, word size, memory size, clock speed, etc. These features are briefly explained below:
(A) Word Size
Word size is the maximum number of bits that a microprocessor can process at a time. Earlier, a word was of 8 bits, as it was the maximum limit at that time. At present, the minimum word size is 16 bits and maximum word size is 64 bits.
(B) Memory Size
Depending upon the word size, the size of RAM varies. Initially, RAM was very small (4MB) due to 4/8 bits word size. As word size increased to 64 bits, it has become feasible to use RAM of size upto 16 Exabytes (EB).
(C) Clock Speed
Clock speed simply means the number of pulses generated per second by the clock inside a computer. The clock speed indicates the speed at which the computer can execute instructions. Earlier, it was measured in Hertz (Hz) and Kilohertz (kHz). But with advancement in technology , it is now measured in Gigahertz (GHz), i.e., billions of pulses per second.
(D) Cores
Core is a basic computation unit of the CPU.
Microcontrollers
The microcontroller is a small computing device which has a CPU, a fixed amount of RAM, ROM and other peripherals all embedded on a single chip. Washing machine, digital camera, remote controller, microwave are few examples of microcontrollers.
Software:-
The software comprises a set of instructions
Need of Software
The sole purpose of a software is to make the computer hardware useful and operational.
The software can be broadly classified into three categories viz.
System software:-
The software that provides the basic functionality to operate a computer. Examples of system software include operating systems, system utilities, device drivers, etc.
Operating system:-
The operating system is a system software that operates the computer. Some of the popular operating systems are Windows, Linux, Macintosh, Ubuntu, Fedora, Android, iOS, etc.
- System Utilities:- Software used for maintenance and configuration of the computer system is called system utility. for example, anti-virus software, disk cleaner tool, disk compression software, etc.
- Device Drivers:- The purpose of a device driver is to ensure proper functioning of a particular device.
Classification of Programming Languages
Two major categories of computer programming languages are low-level languages and high-level languages. Low level language or machine language includes 0 and 1. High level language include C++,Java, Python, etc.
To convert low level language into high level language and vise versa translator is required. There are three types of translators:-
Compiler:- It translate the whole program in one go.
Interpreter:- It translate the program line by line.
Assembler:- To convert assembly language
Application software:-
This specific software that works on top of the system software is termed as application software. There are again two broad categories of application software —
General Purpose Software:-
The application software developed for generic applications, to cater to a bigger audience in general are called general purpose software for example Adobe Photoshop, GIMP, Mozilla web browser, iTunes, etc.
Customised Software :-
These are custom or tailor-made application software, that are developed to meet the requirements of a specific organisation or an individual.
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