× Back Introduction to Computers Components of Computer Hardware Software Categories of Computer Generation of Computer Hardware Organization of a Computer
Next Topic →

Introduction to Computers

Definition :

  1. A programmable usually electronic device that can store, receive, and process data.
  2. A computer is a programmable machine designed to perform arithmetic and logical operations automatically and sequentially on the input given by the user and give the desired output after processing.

Functions of computer :

characteristics of computer :

  1. Speed → The computer can process data very fast at the rate of millions of instructions per second.
  2. Accuracy → Computers provide a high degree of accuracy. They respond to the user as per the input instructions.
  3. Storage Capacity → Computers are capable of storing huge amounts of data which depends on the capacity of the hard disk.
  4. Versatility → Computers can do different types of work simultaneously. They can perform multiple tasks at the same time.
  5. Automation → Once the instruction to do any work is given to the computer, the computer does its work automatically by itself.
  6. Diligence (steady and careful application) → Unlike human beings, a computer is free from monotony (remaining same), tiredness, lack of concentration, etc. and can work for hours without creating any errors.
  7. Secrecy → Leakage of information is reduced by creating a login system with password protection.
  8. Reliability → Computers are more reliable than human beings.
    • Computer always produce exact results.
    • The possibility of error occurs only if the input is wrong, i.e., the computers never make mistakes of their own accord.

Capabilities of Computer :

Limitations of computer :

Application of computer in today's world :

Components of Computers

There are five basic components of the computer that help make this processing of data easier and more convenient.

  1. Input Unit
  2. Output Unit
  3. Memory Unit
  4. Control Unit
  5. Arithmetical and Logical Unit

Input Unit

Output Unit

Memory Unit

Control Unit

Arithmetic & Logical Unit

Central Processing Unit (CPU)

Hardware

Computer Hardware is defined as the physical part or component of a computer system which can be felt, seen and touched.

Types of Hardware Component used in Computer

Cabinet Case

  • Caninet case comes in various shape and sizes but commonly used case is a tower case whose height ranges from 15 to 25 inches.
  • They enable different types of hardware devices to be fit in themselves to make it a whole and all the devices are connected to the case using screws.
  • The commonly attached hardware devices to the PC case are Power supply, Motherboard, CPU, Ram, Hard disk, DVD-RW

Motherboard

  • The computer motherboard or mainboard is nothing but a piece of PCB (printed circuit board) where all the other devices are connected to it using cables & wires.
  • Motherboard generally distributes all the voltages and power received from power supply to other parts of the hardware devices attached to the PC.

RAM

  • RAM (Random Access Memory) is an essential part of the computer system which is used for storing data or program temporarily.
  • It is a volatile memory that tends to lost data when power is missing from a power supply.
  • When RAM is found missing mother board gives a sound, and not display is found on monitors.

Hard Disk Drive

  • Computer Hard disk drives are used to store the data permanently.
  • It is type of non-volatile memory that does not lose data or programs when there is no power.
  • Nowadays huge volume of data can be stored in a hard disk which are called as secondary storage hardware devices.
  • The hard disk capacity is measured in MB-MEGABYTES, GB-GIGAbYTES & TB-TERABYTES

CPU

  • CPU stands for Central Processing Unit which is responsible for almost all the operation computer system performs.
  • CPU performs Arithmetical and Logical Operation which includes additon, subtraction, division, and multiplication, and logical operations include comparision, less and greater values.
  • Every input which is sent by input devices is first collected in primary memory and later transfered to the CPU for further processing.

SMPS (Power Supply)

  • SMPS is known as Switching Mode Power Supply. Which is responsible to give power to the motherboard later this power is distributed among the other hardware devices for better functionality.
  • Mainly three types of power supply is used in modern day PC
    • AT (Advance Technology)
    • AT-X (Advanced Technology-Extended)
    • AT-XT (Advanced Technology with Extended Technology)

Keyboard

  • The keyboard is an input device that is primarily used for entering text as input to the CPU.

Mouse

  • The mouse is a Pointing device that is used for selecting, pinting, and to drag icons, files, and folders from one location to another in hard drives.

Monitors

  • Monitors are display units or commonly called as VDU which stands for [visual disply unit] they are used to display information received from computers on their screen.
  • They are also called as SOFTCOPY Terminals.
  • Types of monitors
    • CRT (Cathode Ray Tube) Monitors → The old type of monitors is the CRT monitor. This is most commonly used with television screens and other monitors perfect for streaming, design work and more.
    • LCD (Liquid Crystal Display) Monitors → LCD moniters were the most popular type of monitor for a few years. These monitors utilize a layer of color or monochrome pixels between two layers of electrodes and polarizing.
    • Touch Screen Monitors → It enables users to interact with the computer by using a finger or stylus instead of using a mouse or keyboard.
    • LED Monitors → It is a flat screen computer monitor, which stands for light-emitting diode display. It is lightweight in terms of weight and has a short depth.
    • OLED Monitors → It is a new flat light-emitting display technology, which is more efficient, brighter, thinner and better refresh rates feature and contrast as compared to the LCD display.

Printers

  • Printers are hardware component of the computer which is often used for producing outputs on papers as a HARDCOPY.
  • There are two types of printers
    • Impact printers → It is a type of printer that works by direct contact of an ink ribbon with paper. These printers are typically loud but remain in use today because of their unique ability to function with multipart forms. An impact printer has mechanisms resembling those of a typewriter. Examples → Dot-Matrix printers, Daisy-wheel printers, and line printers.
  • Non-Impact Printers → It is a type of printers that does not hit inkjet technologies. Non-impact printers are generally much quiter. They are less likely to need maintenance or repairs than earlier impact printers. Examples → inkject printers and laser printers.

Daisy-wheel Printer ↓

  • A daisy-wheel printer is an early type of impact printer invented in 1969.
  • The printer uses a metal or plastic disk containing each of the letters, numbers, and other characters it supports.

Dot matrix printer

  • A dot matrix printer is an impact printer that prints using a fixed number of pins or wires.

Laser Printer

  • Laser Printers use small beams of light, or lasers, to permanently draw text or images onto paper.

Inkjet Printer

  • Inkjet printers described as all-in-one printers come equipped with scanning and photocopying capabilities, in addition to printing.

Thermal Printer

  • thermal printers use a heated printhead to produce an image. This process creates images with high quality prints that can withstand greater abuse.

Speakers

  • Speakers are used to output digital signals.
  • You can use a speaker for hearing sound, videos and playing games.

Software

It can be defined as a set of instructions or collections of programs which are designed and developed to perform specific tasks.

System Software

Different Types of System Software & Their Uses

  • Translators
    • These are those programs that translate codes that are written in high-level or Assembly language into Machine Language or that language that is easily understood by the computer.
    • Assembler
    • Interpreter
    • Compiler
  • Device Drivers
    • These programs are used to help better functionality of hardware devices. Such as mouse, sound cards, and keyboards.
  • Utility Programs
    • Format Defragmentation, cleaning of hard disk space & installing and removing application programs from computer.
    • These utility programs help the user to better communicate and interact with software and hardware.
  • Operating System
    • This acts as the primary interface between a user and computer hardware.
    • It presents the user with a GUI (Graphical User Interface) where the user can directly communicate or interact with hardware and software used in computer systems.
    • The system software manages and controls hardware and user inputs.
    • They are also used in providing an interface for the development of application.

Application Softwares of Computer

Application Sofware is a program that is designed and developed for specific purposes and for a special task that is directly used by the user.

Categories of Computers

Now let us discuss each type of computer in detail:

Supercomputer :

Mainframe computer:

Minicomputer:

Workstation:

PC (Personal Computer):

Analogue Computer:

Digital Computer:

Hybrid Computer:

Generation of Computers

First Generation Computers: Vacuum Tubes (1940-1956)

Main characteristics of first generation computers are:

Main electronic component

Vaccum tube.

Programming language

Machine language

Main memory

Magnetic tapes and magnetic drums

Input/output devices

Paper tape and punched cards

Speed and size

Very slow and very large in size (often taking up entire room).

Examples of the first generation

IBM 650, IBM 701, ENIAC, UNIVAC1, etc.

Advantages and Disadvantages of first generation computers

Advantages

  • They were capable of making arithmetic and logical operations
  • They used the electronic values in place of the key punch machines or the unit record mahcines.

Disadvantages

  • They were too big in size, very slow, low level of accuracy and reliability.
  • They consumed lot of electricity, generated a lot of heat and break down frequently.

Second Generation Computers: Transistors (1956-1963)

Main characteristics of second generation computers are:

Main electronic component

Transistor

Programming language

Machine language and assembly language

Main memory

Magnetic core and magnetic tape/disk.

Input/output devices

Magnetic tape and punched cards

Power and size

Smaller in size, low power consumption and generated less heat (in comparision with the first generation computers).

Examples of the second generation

PDP-8, IBM1400 series, IBM 7090 and 7094, UNIVAC 1107, CDC 3600 etc.

Advantages and Disadvantages of second generation computers

Advantages

  • They required very small space, were very fast and reliable and dependable.
  • They used less power and dissipated less heat and had large storage capacity.
  • They used better peripheral devices like card readers and printer etc.

Disadvantages

  • They did not have any operating system and used assembly languages.
  • They lacked in intelligence and decision making and needed constant upkeep and maintenance.

Third Generation Computers: Integrated Circuits (1964-1971)

Main characteristics of third generation computers are:

Main electronic component

Integrated circuits(ICs)

Programming language

High-level languages

Memory

Large magnetic core, magnetic tape/disk

Input/output devices

Magnetic tape, monitor, keyboard, printer, etc.

Examples of the third generation

BM 360, IBM 370, PDP-11, NCR 395, B6500, UNIVAC 1108, etc

Advantages and Disadvantages of third generation computers

Advantages

  • The size was very small in comparison less costly and built with thousands of transistor which were very cheap.
  • They used faster better device for storage, called auxiliary backing or secondary storage.
  • They used operating system for better resource management and used the concept of time sharing and multiple programming.

Disadvantages

  • They created lot of problems to the manufacturers at their initial stages.
  • They lacked thinking power and decision making capability.
  • They could not provide any insight into their internal working.

Fourth Generation Computers: Micro-processors (1971-1989)

Main characteristics of fourth generation computers are:

Main electronic component

Very large-scale integration (VLSI) and the microprocessor (VLSI has thousands of transistors on a single microchip).

Memory

semiconductor memory (such as RAM, ROM, etc.)

Input/output devices

pointing devices, optical scanning, keyboard, monitor, printer, etc.

Examples of the fourth generation

IBM PC, STAR 1000, APPLE II, Apple Macintosh, Alter 8800, etc.

Advantages and Disadvantages of fourth generation computers

Advantages

  • They were very small in size, and cost of operation was very less.
  • They were very compact faster and reliable as they used very large scale integrated circuits.
  • They were capable of facilitating the interactive on line remote programming by which one sitting at the distant place can get his programs executed by centrally located computer.

Disadvantages

  • They are less powerful and had less speed than the main frame computers.
  • They lacked thinking power and decision making ability.
  • They had less storage capacity and needed further improvement.

Fifth Generation Computers

Main characteristics of second generation computers are:

Main electronic component

Based on artificial intelligence, uses the Ultra Large-Scale Integration (ULSI) technology and parallel processing method (ULSI has millions of transistors on a single microchip and Parallel processing method use two or more microprocessors to run tasks simultaneously).

Language

Understand natural language (human language).

Size

Portable and small in size.

Main memory

Examples of the fifth generation

Desktops, laptops, tablets, smartphones, etc.

Advantages and Disadvantages of fifth generation computers

Advantages

  • They are oriented towards integrated data base development to provide decision models.
  • They faster very cheap and have the highest possible storage capacity.
  • They have thinking power and decision making capability and thereby they will be able to aid the executives in the management.

Disadvantages

  • They need very low level languages; they may replace the human force and cause grievous unemployment problems.
  • They may make the human brains dull and doomed.

Hardware Organization of a Computer

Computer Hardware Configuration

Memory Units

There are two memory units. i.e., Main Memory and Control Memory.

  • Main Memory
    • Memory is an essential component of computer hardware.
    • It enables a user to perform basic tasks on the system.
    • This memory is also known as Random Access Memory (RAM).
    • This computer part stores operating system software, applications and information related to the CPU to have fast and direct access to the stored data and perform tasks.
    • It is one of the fastest types of memory that allows reading and writing data.
    • RAM is further divided into two parts:
      • SRAM
        • It stands for Static Random Access Memory.
        • It is mainly used as a source of memory in embedded devices.
        • The data stored in SRAM does not need to be refreshed continuously.
        • This stored information in the memory remains a static image until it is overwritten or deleted.
        • SRAM is more preferred over DRAM for specific uses like caches located in CPU, as it is less dense and more power-efficient when not in use.
      • DRAM
        • It stands for Dynamic Random Access Memory
        • DRAM is a predominant memory source in PC and workstations.
        • The memory constantly restores the information held in the memory.
        • DRAM refreshes the data continously by sending millions of pulses per second to the memory storage block.
        • The density of DRAM makes it a better choice for main memory.
  • Control Memory
    • A control Memory is a part of the control unit.
    • A control memory consists of fixed microprograms that connnot be modified frequently.
    • It contains microinstructions that specify the internal control signals required to execute register micro-operations.
    • The machine instructions generate a micro instructions chain in the control memory that generates micro-operations that fetches instructions from the main memeory, comput an effective address, execute the operation, return control to fetch phase and continue the cycle.

Registers

  • The Registers are very fast computer memory used to execute programs efficiently.
  • This is done by giving access to commonly used values, i.e., values in the point of execution at that instant.
  • Hence, several classes of CPU registers work in coordination with the computer's memory to run operations efficiently.
  • Although accessing instructions from RAM is faster with a hard drive, it still is not enough for the CPU. For even better processing, registers are used.
  • Six registers commonly used in computer hardware are as follows:
    • Process Unit Register: AC(accumulator), AR(Address Register), PC(Program Counter), DR(Data Register).
    • Control Unit Register: SBR(Subroutine Register), CAR (Control Address Register).
  • Process Unit Registers
    • A processor register can hold an instruction, an address, or data such as bit sequence or individual characters.
    • These registers are required for manipulating data and storing a memory address.
    • After the current instruction's execution is completed, these registers are used to calculate the address of the next instructions.
    • Let's discuss some process unit registers used in computer hardware in detail:
      1. Accumulator (AC):
        • This is general-purpose processing register frequently used to store data taken from the memory.
        • It varies in numbers according to different microprocessors.
        • This register consists of 16 bits.
      2. Address Register (AR)
        • This register consists of 12 bits and is used to store the memory's address.
      3. Program Counter (PC)
        • This is ued to keep track of the execution of a program.
        • These registers consits of the memory address of the next instruction to be fetched.
        • It points to the next instruction's address to be fetched from the main memory when the previous instruction is executed.
        • It also counts the number of instructions.
        • The incrementation of the program counter depends on the type of architecture: For a 32-bit architecture, the counter gets incremented by four every time to fectch the instructions.
        • This register consists of 12 bits.
      4. Data Registers (DR)
        • These registers consist of 16 bits.
        • They are used to hold memory operands.
  • Control Unit Registers
    • Two control unit registers are used in computer hardware, i.e., SBR(Subroutine Register) and CAR (Control Address Register).
      1. Subroutine Register (SBR)
        • This registesr stores the return address for a substance whose value is further used to return the micro-program from the subroutine.
        • (Subroutine calls are the special type of branch where we return to one instruction below the calling instruction - provision must be made to save the return address since it cannot be written into ROM.)
      2. Control Address Register (CAR)
        • This register receives addresses from four different paths.
        • A multiplexer is used for this purpose.

Multiplexers

  • A multiplexer is a combinational circuit that contains several data inputs and a single data output depending on the select inputs.
  • They are generally denoted by MUX.
  • It also has data selector lines that specify which input signal needs to be switched to the output line.

Arithmetic and Logical Unit

  • ALU is a main component of the CPU that performs arithmetic and logic operations.
  • An ALU is also known as an integer unit, an integrated circuit within a CPU.
  • It is the last component to perform calculations in the processor.
  • It can perform all processes related to arithmetic and logic operations, including additon, subraction, shifting operations, and boolean comparisions (OR, AND and Not).
  • It is further split into arithmetic units (AU) and logic units (LU).
  • The operands and code used by the ALU help in predicting the operations that need to be performed according to the input data.
  • It sends the information to the memory after processing.
  • Besides addition and subtraction, ALU also handles the multiplication of two integers whose result is an integer.
  • However, division operations may not be performed by ALUs as division operations may produce floating-point numbers.
  • Instead, the floating-point unit (FPU) usually handles the non-integer calculations.
  • Additionally, we can design an ALU to perform any operation.
  • However, it becomes constly as the operations become complex as ALU takes up more space in the CPU.
  • The ALU handles the calculations required by the CPU.
  • Most of the operations among them are logical.
  • The ALU design decides how powerful the CPU will be.
  • More power means more heat and energy consumption: hence, it must be a moderation between complex and powerful ALU to adjuct the cost and speed.
  • The main operations performed by an ALU are as follows:
    1. Logical Operations → It consists of AND, OR, NOT, NAND, XOR, etc
    2. Bit-Shifting Operations → This operation is responsible for the displacement of bits to the right or left by a certain number of places, known as a multiplication operations.
    3. Arithmetic Operations → Multiplication and division operations are costly. Hence, we can substitute addtion in multiplication and subtraction in divisio.

References