FUNDAMENTALS OF COMPUTERS
Introduction of computers:
The first computer was invented by Charles Babbage (1822) but was not built until 1991, Alan Turing invented computer science. The ENIAC (1945) was the first electronic general-purpose digital computer; it filled a room. The Micral was the world’s first “personal computer” (1973).
Computer is an electronic device that receives input, stores or processes the input as per user instructions and provides output in desired format.
A computer is a device that accepts information (in the form of digitalized data) and manipulates it for some result based on a program, software, or sequence of instructions on how the data is to be processed.
GENERATIONS OF COMPUTERS
The meaning of generations was derived from changes in the hardware technology of computers, but in present times, the meaning of generations is assumed by changes in the technology of both hardware and software.
History of computers – generation of computers
The generation of computers is mainly divided into five parts.
1st Generation
2nd Generation
3rd Generation
4th Generation
5th Generation
Note: Each generation of computers is defined by the technology they use.
First Generation (1942-1956)
First-generation computers used vacuum tubes as the main electronic component and a magnetic drum for data storage.
If we talk about vacuum tubes, these were the basic components of memory and CPU at that time. These components heated up very quickly, due to which the computer also heated up.
The weight of this computer was about 30 tons and it was as much as 50×30 rooms. They were very large in size. And an entire room was needed to keep it.
18,000 vacuum tubes were used in this computer.
1,50,000 watts of power was required to operate it.
This generation of computers required AC (Alternating Current).
This computer takes 200 microseconds to add and subtract and 2000 microseconds to multiply.
These computers were very expensive, heat emission was very high due to which it was very important to cool them and at the same time their maintenance was very difficult.
Machine language was used as its programming language to operate first-generation computers.
Punch cards, paper tape, and magnetic tape were used as input and output in first-generation computers.
First-generation computers were able to solve one problem at a time
Vacuum Tubes
Many computers were built in the first generation such as
ENIAC
EDVAC
EDSAC
UNIVAC
IBM-701
ENIAC (Electronic Numerical Integrator and Computer)
The first electronic computer ENIAC was invented by John Fish and J. Presper Eckert of the University of Pennsylvania, USA.
It was built for the United States Army, counts their artillery firing table.
Second Generation (1956-1965)
Second-generation computers used transistors as electronic devices.
The transistor size was much smaller than that of the vacuum tube and the power consumption was also much lower.
Compared to the first generation, it was more reliable and able to operate faster.
This generation used magnetic cores as primary memory.
Magnetic tape and magnetic disks were used for secondary memory.
In this generation, assembly and machine language have been made more easy and powerful.
Many computers were built in the second generation such as
IBM 7030
Honeywell 400
CDC 1604
Third-Generation (1965-1975)
In third-generation computers, integrated circuits were used in place of transistors.
The integrated circuit is made of silicon. Integrated circuits first used 10–20 electronic devices and this technique is called small-scale integration.
The third generation used more storage magnetic tape and magnetic disks.
Keyboards and monitors were used for input/output by this generation of computers
MICR, plotter and scanner were invented in this generation.
In this generation, the concept of time-sharing and multi-programming operating systems was introduced.
Many new high-level programming languages were introduced in this generation such as Pascal, Basic, Fortran.
Integrated Circuits
MICR (Magnetic Ink Character Recognition) in Computers
MICR (Magnetic Ink Character Recognition) is a technology used primarily in the banking industry to process and verify checks and other financial documents. It allows computers to read printed characters using magnetically charged ink.
Many computers were built in the third generation such as
IBM-360
IBM-370
CDC-6600
PDP-8
PDP-11
Fourth-Generation (1975-1989)
Microprocessors were introduced in the fourth generation, in which thousands of ICs could be manufactured on a single chip.
Large-scale integration was created by assembling around 5000 transistors together and over time this large-scale integration was expanded to form very large-scale integration.
The first microchip was built by Intel Corporation in 1971, the Intel-4004. This small chip came to be called a microprocessor.
The use of microprocessors greatly reduced the size of computers of this generation.
In this generation of computers, the storage device was absorbed into the computer itself, which greatly reduced the size of the computer and due to this, the personal computer could reach home.
In this generation, the concept of time-sharing, real-time processing distributed operating systems was used.
In this generation, C, C ++, DBASE were used as new high-level programming languages.
Supercomputers like CRAY were also born in the same generation, which could perform about a billion calculations in a second.
Many computers were built in the fourth generation such as
CRAY-I
CRAY-II
APPLE-II
VAX-9000
Fifth-Generation (1989-till)
As the fifth generation, a new technology emerged, called Ultra Large-scale Integration.
In this generation, the concept of artificial intelligence, voice recognition, mobile communication, satellite communication, signal data processing was introduced.
Java, VB, and .Net were introduced in this generation in high-level programming languages.
Today’s computers are so advanced that they are being used in every specific area, basic accounting, engineering, building construction, space, and other types of research work.
In this generation every day an attempt is being made to reduce the size of the computer, as a result of which we are also in the shape of the clock.
With the help of the internet, we can exchange documents, information, and money.
Ultra Large-scale Integration
In the fifth generation, many computers were built such as
IBM
NOTEBOOK
PARAM
PENTIUM
Sixth generation (future generations)
As of 2024, most still consider us to be in the fifth generation as AI continues to develop. One possible contender for a future sixth generation is the quantum computer. However, until quantum computing becomes more developed and widely used, it is still only a promising idea.
Some people also consider nanotechnology to be part of the sixth generation. Like quantum computing, nanotechnology is largely still in its infancy and requires more development before becoming widely used.
With a new generation of computers it’s also possible how we interact with a computer may also change. New ways of how we may interact with the next generation of computers include only using our voice, AR (Augmented Reality), VR (Virtual Reality), or MR (Mixed Reality).
The basic parts of a computer are as follows −
Input Unit
All computers accept inputs. An input is data that is entered into or received by a computer. This could include a user pressing a key on a keyboard, clicking a mouse to select something on screen or tapping a touch pad.
Some computer devices can also be categorized as input devices because we use these devices to send instructions to the computer, some examples of computer input devices are:
Mouse
Keyboard
Touchscreen
Mics
Webcam
Touchpad
Trackpad
Image scanner (scanners)
Trackball
Keyboard
The most common input device used for entering text. Includes keys for word processing and data inputting, and for performing specific functions. computer keyboard is a peripheral input device modelled after the typewriter keyboard which uses an arrangement of buttons or keys to act as electronic switches.
Keyboard keys
Alphabetical, numeric, and punctuation keys are used in the same fashion as a typewriter keyboard to enter their respective symbol into a word processing program, text editor, data spreadsheet, or other program. Many of these keys will produce different symbols when modifier keys or shift keys are pressed.
The alphabetic characters become uppercase when the shift key or Caps Lock key is depressed. The numeric characters become symbols or punctuation marks when the shift key is depressed. The alphabetical, numeric, and punctuation keys can also have other functions when they are pressed at the same time as some modifier keys.
The Space bar is a horizontal bar in the lowermost row, which is significantly wider than other keys. Like the alphanumeric characters, it is also descended from the mechanical typewriter. Its main purpose is to enter the space between words during typing. It is large enough so that a thumb from either hand can use it easily. Depending on the operating system, when the space bar is used with a modifier key such as the control key, it may have functions such as resizing or closing the current window, half-spacing, or backspacing. In computer games and other applications the key has myriad uses in addition to its normal purpose in typing, such as jumping and adding marks to check boxes. In certain programs for playback of digital video, the space bar is used for pausing and resuming the playback.
Important keys and uses in Word:
Tab – Moves the cursor .5’’
Caps Lock – Keeps typed letters capitalized until turned off
Control – Can be used for keyboard shortcuts
Spacebar – Inserts one space to the right of the cursor every time you press it
Shift – Can be used to create capital letters or special characters shown on the top level of keys
Enter – Moves cursor down one line
Backspace – Deletes characters to the left of the cursor
Delete – Removes characters to the right of the cursor
Keyboard Symbol
+
Plus
“
Double Quote
–
Minus
&
Ampersand
*
Asterisk
#
Hash
/
Slash
$
Dollar
\
Back slash
^
Caret
%
Percent
<
Lesser than
|
Vertical bar
>
Greater than
~
Tilde
=
Equal to
?
Question mark
(
Open Parenthesis
!
Exclamation mark
)
Close Parenthesis
,
Comma
[
Open bracket
.
Full stop
]
Close bracket
;
Semicolon
{
Open Set bracket
:
Colon
}
Close Set bracket
‘
Apostrophe
_
Underscore
Mouse
The most popular pointing device used to control the cursor on the screen and activated when moved across a flat surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface of a computer. The first public demonstration of a mouse controlling a computer system was in 1968. Mice originally used two separate wheels to track movement across a surface: one in the X-dimension and one in the Y. Later, the standard design shifted to utilize a ball rolling on a surface to detect motion.
Most modern mice use optical sensors that have no moving parts. Though originally all mice were connected to a computer by a cable, many modern mice are cordless, relying on short-range radio communication with the connected system.
In addition to moving a cursor, computer mice have one or more buttons to allow operations such as the selection of a menu item on a display. Mice often also feature other elements, such as touch surfaces and scroll wheels, which enable additional control and dimensional input.
Microphone – Used to convert analogue sound waves into a digital form that can be saved and manipulated by the computer. A microphone can also be used to input voice commands but they do not work well in noisy environments.
Scanner – Works in a similar way to a photocopier. Captures images from the source which are then converted into a digital form that can be stored.
Output devices
The output is how the computer presents the results of the process. Outputs can be returned to the user in many ways such as text on a screen, printed materials, or as sound from a speaker.
Monitor:
The main output device of a computer. It forms images by converting electrical energy into light in the form of tiny dots on the screen called pixels. The sharpness of the image depends upon the number of pixels.
Printer
Used to print information on paper. Commonly uses either lasers or inkjets to precisely place ink onto the page to recreate text and high-quality images.
Speaker – Converts digital signals into audible sound waves.
Projector – A device that is used to project video output from the computer onto a wall or screen.
Control Unit (CU) − As the name suggests, this unit controls all the functions of the computer. All devices or parts of computer interact through the control unit.
Arithmetic Logic Unit (ALU) − This is the brain of the computer where all arithmetic operations and logical operations take place.
Arithmetic operations − Examples include calculations like addition, subtraction, differentials, square root, etc.
Logical operations − Examples include comparison operations like greater than, less than, equal to, opposite, etc.
Memory − All input data, instructions and data interim to the processes are stored in the memory.
Memory is of two types –
primary memory and secondary memory. Primary memory resides within the CPU whereas secondary memory is external to it.
Central processing unit (CPU): Control unit, arithmetic logic unit and memory are together called the central processing unit or CPU. CPU is the most important hardware component in a computer.
The CPU receives instructions and data from an input or memory. The instructions and data are processed by the CPU and the results are either sent to an output or transferred to secondary storage. Data is held in primary storage while it is being processed.
Input is received from an input device such as a keyboard, mouse, camera or scanner. Output is sent to an output device such as a monitor, printer or speaker.
Computer devices like keyboard, mouse, printer, etc. that we can see and touch are the hardware components of a computer. The set of instructions or programs that make the computer function using these hardware parts are called software. We cannot see or touch software. Both hardware and software are necessary for working of a computer.
Motherboard:
The motherboard is the main circuit board of a computer. It connects the CPU and read only memory (ROM), which are mounted on the motherboard, and includes random access memory (RAM) expansion slots.
Processor:
The processor is a chip or a logical circuit that responds and processes the basic instructions to drive a particular computer. The main functions of the processor are fetching, decoding, executing, and write back the operations of an instruction. The processor is also called the brain of any system which incorporates computers, laptops, smartphones, embedded systems, etc. The ALU (Arithmetic Logic Unit) and CU (Control Unit) are the two parts of the processors. The Arithmetic Logic Unit performs all mathematical operations such as additions, multiplications, subtractions, divisions, etc and the control unit works like traffic police, it manages the command or the operation of the instructions. The processor communicates with the other components also they are input/output devices and memory/storage devices.
Characteristics of Computers (advantages)
Computers have several key characteristics that make them essential for various applications. Here are the main ones:
1. Speed
Computers can process data and execute tasks millions of times faster than humans.
Example: A modern CPU can perform billions of instructions per second (GHz speed).
2. Accuracy
Unlike humans, computers do not make mistakes unless there is a software or hardware error.
Example: In calculations, computers provide precise results without approximation errors.
3. Automation
Once a task is programmed, a computer can perform it without further human intervention.
Example: Automated banking transactions, payroll processing, and industrial control systems.
4. Versatility (Multitasking)
A computer can handle multiple tasks at once, such as browsing the web, running software, and playing music simultaneously.
Example: Running multiple applications like MS Word, Excel, and Zoom at the same time.
5. Storage
Computers can store vast amounts of data permanently or temporarily.
Example: Hard drives, SSDs, and cloud storage can hold terabytes (TBs) of data.
6. Connectivity (Communication)
Computers can communicate with other devices via the internet, Bluetooth, or LAN/Wi-Fi.
Example: Emails, video calls, and cloud computing services.
7. Artificial Intelligence & Learning
Modern computers use AI and Machine Learning to analyze data and make decisions.
Example: ChatGPT, self-driving cars, voice assistants (Siri, Alexa).
8. Diligence (No Fatigue)
Computers do not suffer from tiredness, emotions, or lack of concentration like humans.
Example: A computer can run 24/7 without losing efficiency.
9. Logical Decision Making
Computers follow predefined logic and algorithms to solve problems.
Example: Traffic light systems, automated trading bots, and medical diagnosis AI.
10. Security & Data Protection
Computers provide security features like encryption, firewalls, and biometric authentication to protect data.
Example: Fingerprint sensors on smartphones, VPNs, and antivirus software.
Disadvantages of Computers
While computers have many advantages, they also come with some drawbacks. Here are the main disadvantages:
1. Cybersecurity Threats & Hacking
Computers are vulnerable to hacking, viruses, and cyberattacks.
Example: Phishing scams, ransomware, and data breaches in banks and businesses.
2. Privacy Concerns
Online activities are often tracked and monitored, leading to privacy issues.
Example: Social media platforms collecting personal data and surveillance technologies.
3. Unemployment Due to Automation
Many jobs are replaced by AI, robots, and automated systems, reducing the need for human labor.
Example: Self-checkout kiosks, customer service chatbots, and manufacturing robots replacing workers.
4. Health Issues
Prolonged computer use can cause eye strain, back pain, obesity, and mental health problems.
Example: Computer Vision Syndrome (CVS), posture problems, and internet addiction.
5. Expensive Upgrades & Maintenance
High-performance computers require frequent upgrades, which can be costly.
Example: Gaming PCs, professional software, and server maintenance.
6. Social Isolation & Reduced Physical Activity
Overuse of computers can lead to social isolation and reduced outdoor activity.
Example: People spending hours on social media or gaming instead of engaging in real-world interactions.
7. Environmental Impact
Computers contribute to electronic waste (e-waste) and high energy consumption.
Example: Discarded laptops, smartphones, and data centers consuming massive electricity.
8. Dependence & Over-Reliance
People rely too much on computers for calculations, decision-making, and daily tasks.
Example: Students using AI for homework instead of learning concepts.
9. Misinformation & Fake News
The internet spreads false information quickly, leading to confusion and misinformation.
Example: Fake news on social media, deepfake videos, and misinformation campaigns.
10. Ethical & Moral Concerns with AI
AI-powered systems can be biased, unethical, or used for harmful purposes.
Example: AI surveillance, deepfake manipulation, and biased hiring algorithms.
Booting in Computers
Booting is the process of starting or restarting a computer. It loads the operating system (OS) into the computer’s memory (RAM) so that it can be used.
Types of Booting
1. Cold Booting (Hard Booting)
When the computer is turned on from a completely powered-off state.
Example: Pressing the power button on a switched-off PC or laptop.
Steps:
Power is supplied to the computer.
The BIOS/UEFI initializes the hardware.
The OS is loaded into RAM.
The system is ready for use.
2. Warm Booting (Soft Booting)
Restarting the computer without turning off the power.
Example: Clicking Restart in Windows or pressing Ctrl + Alt + Del.
Used when:
✅ A system update is installed.
✅ The computer freezes or slows down.
Booting Process (Step-by-Step)
Power On – Computer gets electrical power.
POST (Power-On Self-Test) – BIOS/UEFI checks hardware components.
Bootloader Execution – The system locates the OS bootloader.
OS Loading – The operating system (Windows, macOS, Linux) loads into RAM.
User Login – The system is ready for user interaction.
Common Booting Issues & Solutions
🔴 Black Screen on Startup → Check power supply & monitor.
🔴 Boot Device Not Found → Check hard drive & BIOS settings.
🔴 Slow Boot Time → Disable unnecessary startup programs.
🔴 Frequent Crashes → Update drivers & scan for malware.
Classification of computers
Historically computers were classified according to processor types because development in processor and processing speeds were the developmental benchmarks. Earliest computers used vacuum tubes for processing, were huge and broke down frequently. However, as vacuum tubes were replaced by transistors and then chips, their size decreased and processing speeds increased manifold.
All modern computers and computing devices use microprocessors whose speeds and storage capacities are skyrocketing day by day. The developmental benchmark for computers is now their size. Computers are now classified on the basis of their use or size
Desktop
Laptop
Tablet
Server
Mainframe
Supercomputer
Let us look at all these types of computers in detail.
Desktop
Desktop computers are personal computers (PCs) designed for use by an individual at a fixed location. IBM was the first computer to introduce and popularize use of desktops. A desktop unit typically has a CPU (Central Processing Unit), monitor, keyboard and mouse. Introduction of desktops popularized use of computers among common people as it was compact and affordable.
Riding on the wave of desktop’s popularity many software and hardware devices were developed specially for the home or office user. The foremost design consideration here was user friendliness.
Laptop
Despite its huge popularity, desktops gave way to a more compact and portable personal computer called laptop in 2000s. Laptops are also called notebook computers or simply notebooks. Laptops run using batteries and connect to networks using Wi-Fi (Wireless Fidelity) chips. They also have chips for energy efficiency so that they can conserve power whenever possible and have a longer life.
Modern laptops have enough processing power and storage capacity to be used for all office work, website designing, software development and even audio/video editing.
Tablet
After laptops computers were further miniaturized to develop machines that have processing power of a desktop but are small enough to be held in one’s palm. Tablets have touch sensitive screen of typically 5 to 10 inches where one finger is used to touch icons and invoke applications.
Keyboard is also displayed virtually whenever required and used with touch strokes. Applications that run on tablets are called apps. They use operating systems by Microsoft (Windows 8 and later versions) or Google (Android). Apple computers have developed their own tablet called iPad which uses a proprietary OS called iOS.
Server:
Servers are computers with high processing speeds that provide one or more services to other systems on the network. They may or may not have screens attached to them. A group of computers or digital devices connected together to share resources is called a network.
Servers have high processing powers and can handle multiple requests simultaneously. Most commonly found servers on networks include
File or storage server
Game server
Application server
Database server
Mail server (internet)
Print server
Mainframe computers
Mainframes are computers used by organizations like banks, airlines and railways to handle millions and trillions of online transactions per second. Important features of mainframes are
Big in size
Hundreds times Faster than servers, typically hundred megabytes per second
Very expensive
Use proprietary OS provided by the manufacturers
In-built hardware, software and firmware security features
Super computer
Supercomputers are the fastest computers on Earth. They are used for carrying out complex, fast and time intensive calculations for scientific and engineering applications. Supercomputer speed or performance is measured in teraflops, i.e. 1012 floating point operations per second.
Chinese supercomputer Sunway TaihuLight is the world’s fastest supercomputer with a rating of 93 petaflops per second, i.e. 93 quadrillion floating point operations per second.
Most common uses of supercomputers include
Molecular mapping and research
Weather forecasting
Environmental research
Oil and gas exploration
Software
Software is a collection of instructions or programs that tell a computer how to perform specific tasks. It is the intangible part of a computer system that works with hardware to carry out operations, from basic functions to complex tasks.
Types of Software
System Software
Manages and controls hardware, enabling the application software to work.
Examples:
Operating Systems (OS):
Windows (PCs)
macOS (Apple devices)
Linux (Open-source OS)
Android/iOS (Mobile OS)
Device Drivers: Programs that allow the operating system to interact with hardware (e.g., printer drivers, graphics card drivers).
Application Software
Designed to help users complete specific tasks. It runs on top of system software.
Examples:
Productivity Software:
Microsoft Word (word processing)
Excel (spreadsheets)
PowerPoint (presentations)
Multimedia Software:
Photoshop (image editing)
VLC Media Player (video and audio playback)
Web Browsers:
Google Chrome
Firefox
Safari
Utility Software
Helps manage, maintain, and optimize the performance of a computer.
Examples:
Antivirus Software:
Norton Antivirus
McAfee
Disk Cleanup Tools:
CCleaner
Backup Software:
Acronis True Image
Programming Software
Tools that help software developers create, debug, and maintain applications.
Examples:
IDEs (Integrated Development Environments):
Visual Studio Code
Eclipse
Compilers and Interpreters:
GCC (C/C++ compiler)
Python Interpreter
Hardware
Hardware refers to the physical components of a computer system or device that work together to execute tasks. It is the tangible part of a computer that can be touched and seen, as opposed to software, which is intangible.
Types of Hardware 🛠️
Hardware can be broadly classified into the following categories:
1. Input Devices ⌨️🖱️
Input devices allow users to input data into the computer.
Examples:
Keyboard: For typing text and commands.
Mouse: For pointing, clicking, and navigating.
Scanner: For digitizing physical documents.
Microphone: For audio input.
Webcam: For video input.
2. Output Devices
Output devices allow the computer to display or output data to the user.
Examples:
Monitor: For displaying visual information (text, images, videos).
Printer: For printing physical copies of digital documents.
Speakers: For audio output (sound, music, voice).
Projector: For projecting visual output onto a large screen.
3. Storage Devices
Storage devices store data, both temporarily and permanently, for the computer.
Examples:
Hard Disk Drive (HDD): Magnetic storage for large amounts of data (e.g., 1TB, 2TB).
Solid-State Drive (SSD): Faster, more reliable storage compared to HDDs.
USB Flash Drive: Portable storage for transferring data.
Optical Discs: CD, DVD, or Blu-ray discs for storing data.
Cloud Storage: Remote servers for storing data over the internet (e.g., Google Drive, Dropbox).
4. Processing Devices
Processing devices are responsible for executing the instructions and performing calculations.
Examples:
Central Processing Unit (CPU): The “brain” of the computer that processes data and instructions.
Graphics Processing Unit (GPU): Specializes in rendering graphics and images, often used in gaming and video rendering.
Motherboard: The main circuit board that connects all hardware components.
5. Communication Devices
Communication devices enable the computer to connect to networks and other devices for communication.
Examples:
Network Interface Card (NIC): Connects the computer to a local area network (LAN) or internet.
Modem: Converts digital data to analog signals and vice versa, used for internet connections.
Wi-Fi Adapter: Allows wireless connectivity to networks.
Bluetooth Adapter: For wireless communication with Bluetooth-enabled devices (e.g., headphones, speakers).
6. Power Supply Unit (PSU)
Provides electrical power to all components of the computer.
Examples:
Internal PSU: Inside desktop computers, supplying power to the motherboard, CPU, and other parts.
Laptop Power Adapter: External unit used for powering and charging laptops.
Software vs. Hardware
Aspect
Software
Hardware
Nature
Intangible (instructions, programs)
Tangible (physical components)
Function
Tells the computer how to perform tasks
Performs the physical tasks (e.g., processing, storing data)
Examples
Operating Systems, Apps, Utilities
CPU, RAM, Hard Disk, Monitor, Keyboard
Units of Memory
The storage capacity of the memory is expressed in various units of memory. These are as follows:
Bit
A microprocessor uses binary digits 0 and 1 to decide the OFF and ON state respectively, of various circuits. Furthermore, a bit is the smallest unit of representation in the binary language.
Nibble
A nibble is a collection of 4 bits.
Byte:
A byte is the representation of a group of 8 bits. Moreover, a byte is a unit that expresses any word, symbol, or character in the computer language. Besides, computer memory is always in terms of multiples of bytes.
Word
A computer word is similar to a byte, as it is also a group of bits. Moreover, a computer word is fixed for each computer. At the same time it varies from computer to computer. Besides, the length of a computer word is the word-size or word length. Therefore, a computer stores information in the form of computer word.
Memory measurements:
Computer memory is measured in terms of how many bits it can store. Here is a chart for memory capacity conversion.
1 bit = binary digit
1 nibble = 4 bits
1 byte (B) = 8 bits
1 Kilobytes (KB) = 1024 bytes
1 Megabyte (MB) = 1024 KB
1 Gigabyte (GB) = 1024 MB
1 Terabyte (TB) = 1024 GB
1 Exabyte (EB) = 1024 TB
1 Zettabyte = 1024 EB
1 Yottabyte (YB) = 1024 ZB
Memory
Memory is required in computers to store data and instructions. Memory is physically organized as a large number of cells that are capable of storing one bit each. Logically they are organized as groups of bits called words that are assigned an address. Data and instructions are accessed through these memory address. The speed with which these memory addresses can be accessed determines the cost of the memory. Faster the memory speed, higher the price.
Computer memory can be said to be organized in a hierarchical way where memory with the fastest access speeds and highest costs lies at the top whereas those with lowest speeds and hence lowest costs lie at the bottom. Based on this criteria memory is of two types – primary and secondary. Here we will look at primary memory in detail.
Microprocessor has two types of memory
Primary Memory
Secondary memory
Primary Memory
RAM − Random Access Memory is volatile memory that gets erased when power is switched off. All data and instructions are stored in RAM.
ROM − Read Only Memory is non-volatile memory whose data remains intact even after power is switched off. Microprocessor can read from it any time it wants but cannot write to it. It is preprogrammed with most essential data like booting sequence by the manufacturer.
Secondary memory
Secondary memory device is part of CPU or not, there are two types of secondary memory – fixed and removable.
Let us look at some of the secondary memory devices available.
Hard Disk Drive:
Hard disk drive is made up of a series of circular disks called platters arranged one over the other almost ½ inches apart around a spindle. Disks are made of non-magnetic material like aluminum alloy and coated with 10-20 nm of magnetic material.
Standard diameter of these disks is 14 inches and they rotate with speeds varying from 4200 rpm (rotations per minute) for personal computers to 15000 rpm for servers. Data is stored by magnetizing or demagnetizing the magnetic coating. A magnetic reader arm is used to read data from and write data to the disks. A typical modern HDD has capacity in terabytes (TB).
Solid-state drives (SSD)
Solid-state drives (SSDs) are the most common storage drives today. SSDs are smaller and faster than hard disk drives (HDDs).
CD Drive
CD stands for Compact Disk. CDs are circular disks that use optical rays, usually lasers, to read and write data. They are very cheap as you can get 700 MB of storage space for less than a dollar. CDs are inserted in CD drives built into CPU cabinet. They are portable as you can eject the drive, remove the CD and carry it with you. There are three types of CDs
CD-ROM (Compact Disk – Read Only Memory) − The data on these CDs are recorded by the manufacturer. Proprietary Software, audio or video are released on CD-ROMs.
CD-R (Compact Disk – Recordable) − Data can be written by the user once on the CD-R. It cannot be deleted or modified later.
CD-RW (Compact Disk – Rewritable) − Data can be written and deleted on these optical disks again and again.
DVD Drive
DVD stands for Digital Video Display. DVD are optical devices that can store 15 times the data held by CDs. They are usually used to store rich multimedia files that need high storage capacity. DVDs also come in three varieties – read only, recordable and rewritable.
Pen Drive
Pen drive is a portable memory device that uses solid state memory rather than magnetic fields or lasers to record data. It uses a technology similar to RAM, except that it is non-volatile. It is also called USB drive, key drive or flash memory.
Blu Ray Disk
Blu Ray Disk (BD) is an optical storage media used to store high definition (HD) video and other multimedia filed. BD uses shorter wavelength laser .as compared to CD/DVD. This enables writing arm to focus more tightly on the disk and hence pack in more data. BDs can store up to 128 GB data.
Input/Output Ports
A connection point that acts as interface between the computer and external devices like mouse, printer, modem, etc. is called port. Ports are of two types −
Internal port − It connects the motherboard to internal devices like hard disk drive, CD drive, internal modem, etc.
External port − It connects the motherboard to external devices like modem, mouse, printer, flash drives, etc.
Let us look at some of the most commonly used ports.
Parallel Port
Parallel ports can send or receive 8 bits or 1 byte at a time. Parallel ports come in form of 25-pin female pins and are used to connect printer, scanner, external hard disk drive, etc.
USB Port
USB stands for Universal Serial Bus. It is the industry standard for short distance digital data connection. USB port is a standardized port to connect a variety of devices like printer, camera, keyboard, speaker, etc.
PS-2 Port
PS/2 stands for Personal System/2. It is a female 6-pin port standard that connects to the male mini-DIN cable. PS/2 was introduced by IBM to connect mouse and keyboard to personal computers. This port is now mostly obsolete, though some systems compatible with IBM may have this port.
Infrared Port
Infrared port is a port that enables wireless exchange of data within a radius of 10m. Two devices that have infrared ports are placed facing each other so that beams of infrared lights can be used to share data.
Bluetooth Port
Bluetooth is a telecommunication specification that facilitates wireless connection between phones, computers and other digital devices over short range wireless connection. Bluetooth port enables synchronization between Bluetooth-enabled devices. There are two types of Bluetooth ports −
Incoming − It is used to receive connection from Bluetooth devices.
Outgoing − It is used to request connection to other Bluetooth devices.
Bluetooth icon