IT Application in Business
IT Application in Business
IT Application in Business
UNIT 1
The technology, which is exclusively designed to store, process, and transmit information, is known as
Information Technology. it is the key driver of economic growth of not only a nation, but rather the whole
world.The growth and progress of every sector of the country today depends on the level of Information
Technology.
1. Computer Hardware: Physical equipment used for input, output and processing. The hardware
structure depends upon the type and size of the organization. It consists of an input and an output device,
operating system, processor, and media devices. This also includes computer peripheral devices.
2. Computer Software: The programs/ application program used to control and coordinate the hardware
components. It is used for analysing and processing of the data. These programs include a set of
instruction used for processing information. Software is further classified into 3 types:
System Software, such as an operating system program, which con controls and supports the
operations of a computer system.
Application Software, which are programs that direct processing for a particular use of computers by
end users. Examples are a sales analysis program, a payroll program, and a work processing program.
Procedures, which are operating instructions for the people who will use an information system.
Examples are instructions for filling out a paper form or using a software package.
3. Data: Data are the raw facts and figures that are unorganized that are later processed to generate
information. Softwares are used for organizing and serving data to the user, managing physical storage of
media and virtual resources. As the hardware can’t work without software the same as software needs
data for processing. Data are managed using Database management system.
Database software is used for efficient access for required data, and to manage knowledge bases.
4. Network: Networks resources refer to the telecommunication networks like the intranet, extranet and
the internet.These resources facilitate the flow of information in the organization. Networks consists of
both the physical devices such as networks cards, routers, hubs and cables and software such as operating
systems, web servers, data servers and application servers.
What is computer
Computer is an electronic device that receives input, stores or processes the input as per user instructions
and provides output in desired format.
It renders output just after performing mathematical and logical operations and can save the output for
future use. It can process numerical as well as non-numerical calculations. The term "computer" is derived
from the Latin word "computare" which means to calculate.
A computer is designed to execute applications and provides a variety of solutions through
integrated hardware and software components. It works with the help of programs and represents the
decimal numbers through a string of binary digits. It also has a memory that stores the data, programs,
and result of processing. The components of a computer such as machinery that includes wires,
transistors, circuits, hard disk are called hardware. Whereas, the programs and data are called software.
1. Speed:- Executing mathematical calculation, a computer works faster and more accurately than
human. Computers have the ability to process so many millions (1,000,000) of instructions per second.
Computer operations are performed in micro and nano seconds. A computer is a time saving device. It
performs several calculations and tasks in few seconds that we take hours to solve. The speed of a
computer is measure in terms of GigaHertz and MegaHertz.
2. Diligence:- A human cannot work for several hours without resting, yet a computer never tires. A
computer can conduct millions of calculations per second with complete precision without stopping. A
computer can consistently and accurately do millions of jobs or calculations. There is no weariness or lack
of concentration. Its memory ability also places it ahead of humans.
3. Reliability :- A computer is reliable. The output results never differ unless the input varies. the output is
totally depend on the input. when an input is the same the output will also be the same. A computer
produces consistent results for similar sets of data, if we provide the same set of input at any time we will
get the same result.
4. Automation :- The world is quickly moving toward AI-based technology. A computer may conduct tasks
automatically after instructions are programmed. By executing jobs automatically, this computer feature
replaces thousands of workers. Automation in computing is often achieved by the use of a program, a
script, or batch processing.
5. Versatility :- Versatility refers to a capacity of computer. Computer perform different types of tasks
with the same accuracy and efficiency. A computer can perform multiple tasks at the same time this is
known as versatility. For example, while listening to music, we may develop our project using power
point and Wordpad, or we can design a website.
6. Memory :- A computer can store millions of records. these records may be accessed with complete
precision. Computer memory storage capacity is measured in Bytes, Kilobytes(KB), Megabytes(MB),
Gigabytes(GB), and Terabytes(TB). A computer has built-in memory known as primary memory.
7. Accuracy:- When a computer performs a computation or operation, the chances of errors occurring
are low. Errors in a computer are caused by human’s submitting incorrect data. A computer can do a
variety of operations and calculations fast and accurately.
The general architecture diagram of a computer system is shown in the below figure
Input Unit
The computer components that help humans put data into the computer are called input unit. An input
unit is formed by connecting various input devices, such as a keyboard, mouse, touch screen, modem,
scanner, etc.
A computer receives input in two ways: either manually or directly. In the case of manual data entry, the
user put the data into the computer by hand, either using keyboard or mouse. In case of direct entry, data
is entered into the computer automatically from a source document, such as barcode.
As instructions and data put through different input devices are in the different form, the input unit
converts them into a form that a computer can understand. After it, the input unit sends the data and
instructions to the CPU for further processing.
Central Processing Unit (CPU)
The central processing unit (CPU) is considered as the “brain” of any computer system, which performs all
the processing of input data. Its function is to convert data (input) into meaningful information (output).
In a microcomputer, CPU is a highly complex, extensive set of electronic integrated circuit (IC), which fetch,
examine, and then execute program instructions stored in the main memory of a computer. We also call it
a microprocessor that is basically a single chip.
A central processing unit controls all internal and external devices, as well as performs arithmetic and
logical operations. It operates only on the binary data that consists of “1s” and “0s”.
Moreover, it also controls the usage of main memory to store program instructions and data, as well as
controls the sequence of several operations. The central processing unit has three main subsystems:
Arithmetic and logic unit
Control unit
Registers
Arithmetic and Logic Operations: The CPU performs basic arithmetic operations like addition,
subtraction, multiplication, and division. It also handles logical operations such as comparisons, bitwise
operations, and boolean operations.
Control Unit: The CPU includes a control unit that coordinates and manages the execution of
instructions. It controls the flow of data between the CPU, memory, and other peripherals.
Registers: The CPU features a number of registers that are used to store data and interim findings.
Operands, addresses, and other information needed for calculations are temporarily stored in these
registers. Data transfer between registers and memory is controlled by the CPU.
Output Unit
In a microcomputer, output unit is formed by connecting output devices, such as monitor, speakers,
printer, and plotter to the computer.
An output device is a device that outputs or presents the processes data (result or information) to the
user. The basic function of an output unit is just opposite to that of input unit.
It accepts the outputs (in machine coded form) from the CPU, and converts them into the user
understandable form (which are called information) such as texts, audio, video, or graphical. After
converting it, it sends the converted results to the user with the help of output devices.
User can understand and use the output either in the hard copy or soft copy. The physical form of output
is called hard copy. The electronic form of an output, which usually stores in the computer memory
and/or on the hard disk is called soft copy.
Memory or storage unit is that component of a computer system, which stores the program instructions,
and data before processing starts and stores the information generated by computer before sending them
to the output unit.
A memory unit is basically that area within the computer system, where the CPU stores the program
instructions and data. The memory unit or storage unit of a computer consists of two types of memory or
storage. They are as:
Primary memory (also known as main memory)
Secondary memory
The main memory holds the program instructions and data currently being processed by the CPU, the
intermediate results generated during the calculations, and the recently processed data. When the
instructions and data remain in the main memory, the CPU can access them directly and quickly.
Because of the limited size of main memory, a computer system uses a secondary memory, which is
extensively used to store instructions and data. Then, it sends the stored information to other units of the
computer as and when need.
There are several types of secondary memory devices, such as hard disk drives (HDD), solid-state drives
(SSD), optical disks (including CDs and DVDs), and USB flash drives. These devices have varying storage
capacities, read and write speeds, and different capabilities that make them appropriate for different
types of applications.
Input and Output Devices( Hardware, Software, Human ware and Firmware)
An input/output device, often known as an IO device, is any hardware that allows a human operator or
other systems to interface with a computer. Input/output devices, as the name implies, are capable of
delivering data (output) to and receiving data from a computer (input). An input/output (I/O) device is a
piece of hardware that can take, output, or process data. It receives data as input and provides it to a
computer, as well as sends computer data to storage media as a storage output.
Input Devices
Input devices are the devices that are used to send signals to the computer for performing tasks. The
receiver at the end is the CPU (Central Processing Unit), which has work to send signals to the output
devices. Some of the classifications of Input devices are:
Keyboard
The keyboard is the most frequent and widely used input device for entering data into a computer.
Although there are some additional keys for performing other operations, the keyboard layout is similar to
that of a typical typewriter.
Generally, keyboards come in two sizes: 84 keys or 101/102 keys but currently keyboards with 104 keys or
108 keys are also available for Windows and the Internet.
Keyboard
Types of Keys
Numeric Keys: It is used to enter numeric data or move the cursor. It usually consists of a set of 17 keys.
Typing Keys: The letter keys (A-Z) and number keys (09) are among these keys.
Control Keys: These keys control the pointer and the screen. There are four directional arrow keys on it.
Home, End, Insert, Alternate(Alt), Delete, Control(Ctrl), etc., and Escape are all control keys (Esc).
Special Keys: Enter, Shift, Caps Lock, NumLk, Tab, etc., and Print Screen are among the special function
keys on the keyboard.
Function Keys: The 12 keys from F1 to F12 are on the topmost row of the keyboard.
Mouse
The most common pointing device is the mouse. The mouse is used to move a little cursor across the
screen while clicking and dragging. The cursor will stop if you let go of the mouse. The computer is
dependent on you to move the mouse; it won’t move by itself. As a result, it’s an input device.
A mouse is an input device that lets you move the mouse on a flat surface to control the coordinates and
movement of the on-screen cursor/pointer.
The left mouse button can be used to select or move items, while the right mouse button when clicked
displays extra menus.
Mouse
Joystick
A joystick is a pointing device that is used to move the cursor on a computer screen. A spherical ball is
attached to both the bottom and top ends of the stick. In a socket, the lower spherical ball slides. You can
move the joystick in all four directions.
Joystick
The joystick’s function is comparable to that of a mouse. It is primarily used in CAD (Computer-Aided
Design) and playing video games on the computer.
Track Ball
Track Ball is an accessory for notebooks and laptops, which works on behalf of a mouse. It has a similar
structure to a mouse. Its structure is like a half-inserted ball and we use fingers for cursor movement.
Different shapes are used for this like balls, buttons, or squares.
Track Ball
Light Pen
A light pen is a type of pointing device that looks like a pen. It can be used to select a menu item or to
draw on the monitor screen. A photocell and an optical system are enclosed in a tiny tube. When the tip
of a light pen is moved across a monitor screen while the pen button is pushed, the photocell sensor
element identifies the screen location and provides a signal to the CPU.
Light Pen
Scanner
A scanner is an input device that functions similarly to a photocopier. It’s employed when there’s
information on paper that needs to be transferred to the computer’s hard disc for subsequent
manipulation. The scanner collects images from the source and converts them to a digital format that may
be saved on a disc. Before they are printed, these images can be modified.
Scanner
An Optical Mark Reader is a device that is generally used in educational institutions to check the answers
to objective exams. It recognizes the marks present by pencil and pen.
Optical Mark Reader
OCI stands for optical character recognition, and it is a device that reads printed text. OCR optically scans
the text, character by character turns it into a machine-readable code, and saves it to the system memory.
It is a device that is generally used in banks to deal with the cheques given to the bank by the customer. It
helps in reading the magnetic ink present in the code number and cheque number. This process is very
fast compared to any other process.
A bar code reader is a device that reads data that is bar-coded (data that is represented by light and dark
lines).Bar-coded data is commonly used to mark things, number books, and so on. It could be a handheld
scanner or part of a stationary scanner. A bar code reader scans a bar code image, converts it to an
alphanumeric value, and then sends it to the computer to which it is connected.
Bar Code Reader
Digitizer
Digitizer is a device that is used to convert analog signals to digital signals. it converts signals into numeric
values. An example of a Digitizer is Graphic Tablet, which is used to convert graphics to binary data.
Digitizer
Microphone
The microphone works as an input device that receives input voice signals and also has the responsibility
of converting it also to digital form. It is a very common device that is present in every device which is
related to music.
Output Devices
Output devices are the devices that show us the result after giving the input to a computer system.
Output can be of many different forms like image, graphic audio, video, etc. Some of the output devices
are described below.
Monitor
The monitor is the display unit or screen of the computer. It is the main output device that displays the
processed data or information as text, images, audio or video.The types of monitors are given below.
o CRT Monitor
o LCD Monitor
o LED Monitor
o Plasma Monitor
CRT monitors are based on the cathode ray tubes. They are like vacuum tubes which produce images in
the form of video signals. Cathode rays tube produces a beam of electrons through electron guns that
strike on the inner phosphorescent surface of the screen to produce images on the screen.
The LCD monitor is a flat panel screen that is compact and light-weight as compared to CRT monitors. It is based on
liquid crystal display technology which is used in the screens of laptops, tablets, smart phones, etc.
The LED monitor is an improved version of an LCD monitor. It also has a flat panel display and uses liquid
crystal display technology like the LCD monitors. The LED monitor has many LED panels, and each panel
has several LEDs to backlight the display,
Printer
A printer produces hard copies of the processed data. It enables the user, to print images, text or any other
information onto the paper. Printers enable the generation of tangible copies for record-keeping, presentations,
marketing materials, and other purposes, from household to professional settings. Printers are essential for personal
and commercial use due to their simplicity and adaptability.
o Impact Printers
1. Character Printers
1. Dot Matrix printers
2. Daisy Wheel printers
2. Line printers
1. Chain printers
2. Drum Printer
o Non-impact printers
1. Laser printers
2. Inkjet printers
Speakers
Speakers are important output devices that transform electrical impulses into audible sounds. They're essential to
many modern devices, including computers, televisions, music players, and mobile phones. The audio system
improves the multimedia experience by providing high-quality audio output, whether listening to the song, viewing
films, playing video games, or participating in virtual meetings.
Headphones/Earphones
Headphones and earphones are personal audio devices worn over the ears or inserted into the ear canal, respectively.
They deliver Music to the user directly, giving a private and immersive listening experience. Earphones are tiny and fit
within the ear, whereas headphones have two speakers that cover both ears.
Projector
A projector is an output device that enables the user to project the output onto a large surface such as a big screen or
wall. It can be connected to a computer and similar devices to project their output onto a screen. It uses light and
lenses to produce magnified texts, images, and videos.
1. Hardware: Hardware refers to the physical components of a computer or electronic devices and
resources information. includes components like the central processing unit (CPU), memory (RAM),
storage devices (hard drives, SSDs), input/output devices (keyboard, mouse, monitor), and other
tangible parts. Hardware provides the foundation for a computing system and is responsible for
executing instructions provided by software.
Examples of hardware
There are many different types of hardware. Below are some examples of common hardware components:
CPU: The brain of the computer; responsible for processing all instructions
Hard Drive: A type of long-term storage; used to store data permanently
Graphics Card: Generates images for the monitor
Monitor: Displays images and text generated by the graphics card
Keyboard: Allows users to input text instructions
Mouse: Allows users to input graphical instructions
Printers: Produce physical copies of documents
Scanners : Digitise physical documents into digital format
One example of firmware is the BIOS (Basic Input/Output System) found in computers. The BIOS controls
how the computer starts up and interacts with other devices and software. Another example of firmware
is found in smartphones. The firmware in a smartphone holds the operating system and applications and
so controls how the phone operates and runs applications.
3. Software: Software refers to a collection of programs, data, and instructions that are stored
electronically and run on a computer or electronic device's includes operating systems, applications,
utilities, and any other code that provides specific functionality or services to users. Software can be
categorized into two categories:-
System Software(OS): This type of software manages all of the hardware resources associated with your
computer. For example, when you want to print a document, the OS will send that request to the printer
connected to your computer.
Application software: This type of software allows users to perform specific tasks. For example, Microsoft
Word is application software that allows you to edit text, create layouts,web browser and more.
In summary, hardware is the physical foundation of computing systems, firmware is software embedded
in hardware, software is a collection of programs and data that run on hardware, and humanware
represents the human factor in technology, including user expertise and interaction. All of these
components work together to create a functional and usable technology ecosystem.
Classification of Computers
The computer systems can be classified on the following basis:
1. On the basis of size.
2. On the basis of purpose.
3. On the basis of work type.
Classification on the basis of size
Super computers : The super computers are the most high performing system. Supercomputers are very
expensive and are employed for specialized applications that require an immense amount of
mathematical calculations (number-crunching). They are big and may have multiple CPUs [Central
Processing Units] for faster data and information access. The supercomputer also uses parallel processing
for better functionality, performance, and processing. A speed is measured or counted in “FLOPS”
(Floating Point Operation per Second). It can perform a speed of over 1 billion per second. supercomputer
is a million times faster than the mini, mainframe, and microcomputers because of thousands of
processors installed on them
The supercomputer is designed and developed for special purposes like weather forecasting, scientific
simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design,
and analysis of geological data (e.g. in petrochemical prospecting).
Mainframe computers : They are small in size compared to a supercomputer. Mainframes are fast and
can store a massive amount of data and information. They have extremely impressive data processing and
handling abilities, and hence the number of users can connect to them quickly for better data sharing and
functionality.
Mainframe computers can connect to another microcomputer to form a network.They support
tens of thousands of remote computers and can work as a “Host Computer”; they are pretty good when
considering working with different operating systems.They can store data and deliver millions of
instructions and guidelines per second.
Uses of Mainframe computers
Banking, Government Databases, Airline and Railway Reservation, Population Database.
Mini computers :Minicomputers are considerably smaller in size compared to supercomputers and
mainframe computers.
Minicomputer consists of more than 1 CPU [Central Processing Unit], making them faster than
microcomputers and costlier than microcomputers.
Mini computers work slower than mainframe computers. Minicomputers are called "Workstations" or
"Midrange Computers". Mini computers are extensively used in small businesses and medium-sized
companies.
Micro computers : Microcomputers are compact in shape and size and use a microprocessor, processor,
or CPU for processing and calculations. They are comparatively relatively smaller than other computers.
The microprocessor is cheaper than the technology used by [Mini, Mainframe, and Super].
This computer can be accommodated inside a briefcase and placed on a desk. Therefore these tiny
computers are called “Microcomputers“. The microprocessor is also called CPU [Central Processing Unit]
or Processor. The microprocessors are also known as the heart or brain of a computer. The primary
function of the microprocessor is to perform arithmetic and logical operations at high speed with great
accuracy. Microcomputers can perform trillions of operations per second. Microcomputers are also
called “Personal Computers” [PC]. These are personal computers at low cost, and users can purchase
them from the market.
Uses of Microcomputers.
They are personal or home computers, abundantly used in our daily activities.
They can comfortably work in the banking sector.
Small shops.
Shopping Malls.
General-purpose computer:- A general-purpose computer can be used for this task, as well as many
others. In the early days of computing, general-purpose computers were often referred to as general-
purpose digital computers or general-purpose electronic computers.
Special-purpose computer: Special-purpose computers are designed for one specific task or class of tasks
and wouldn't be able to perform general computing tasks.For example, a router is a special-purpose
computer designed to move data around a network,
Analog Computer: Analog computers are that computer that works with physical quantities like length,
current, height, temperature, pressure, and voltage. Analog computers were used in science and
engineering. Analog computers are designed and developed to measure things despite checking and
counting.
Some Examples of Analog Computers.
Operational Amplifiers, Mechanical integrators, Slide rules, Tide Predictors, Electric Integrators,
Thermometer, Speedometer, Seismometer, Voltmeter, Flight Simulators.
Digital Computers:- Digital computers are those computers that calculate numbers and digits. Today,
analog computers are almost obsolete, and digital computers are used and utilized globally. These
computers convert 0s and 1s to digital format. In other words, convert them into human-readable form.
Examples of Digital Computers
Digital Clock, Calculator, Weighing Machine, Consumer Electronic Equipment, Laptop, ATM Machines,
Smart Phones, Automobiles.
Hybrid Computer:- Hybrid computers are a combination of analog computers and digital computers.
They possess all the qualities of both analog and digital computers.
Examples of Hybrid Computers.
Gasoline Station, Electrocardiogram Machine, Monitoring Machine, Ultrasound Machine.
1. Primary Memory
It is also known as the main memory of the computer system. It is used to store data and programs or
instructions during computer operations. It uses semiconductor technology and hence is commonly called
semiconductor memory. Primary memory is of two types:
RAM (Random Access Memory): It is a volatile memory. Volatile memory stores information based on
the power supply. If the power supply fails/ interrupted/stopped, all the data and information on this
memory will be lost. RAM is used for booting up or start the computer. It temporarily
stores programs/data which has to be executed by the processor. RAM is of two types:
S RAM (Static RAM): S RAM uses transistors and the circuits of this memory are capable of
retaining their state as long as the power is applied. This memory consists of the number of flip flops with
each flip flop storing 1 bit. It has less access time and hence, it is faster.
D RAM (Dynamic RAM): D RAM uses capacitors and transistors and stores the data as a charge on
the capacitors. They contain thousands of memory cells. It needs refreshing of charge on capacitor after a
few milliseconds. This memory is slower than S RAM.
ROM (Read Only Memory): It is a non-volatile memory. Non-volatile memory stores information even
when there is a power supply failed/ interrupted/stopped. ROM is used to store information that is used
to operate the system. As its name refers to read-only memory, we can only read the programs and data
that is stored on it. It contains some electronic fuses that can be programmed for a piece of specific
information. The information stored in the ROM in binary format. It is also known as permanent memory.
ROM is of four types:
PROM (Programmable Read Only Memory): This read-only memory is modifiable once by the user.
The user purchases a blank PROM and uses a PROM program to put the required contents into the PROM.
Its content can’t be erased once written.
EPROM (Erasable Programmable Read Only Memory): EPROM is an extension to PROM where you
can erase the content of ROM by exposing it to Ultraviolet rays for nearly 40 minutes.
EEPROM (Electrically Erasable Programmable Read Only Memory): Here the written contents can be
erased electrically. You can delete and reprogramme EEPROM up to 10,000 times. Erasing and
programming take very little time, i.e., nearly 4 -10 ms(milliseconds). Any area in an EEPROM can be
wiped and programmed selectively.
2. Secondary Memory
It is also known as auxiliary memory and backup memory. It is a non-volatile memory and used to store a
large amount of data or information. The data or information stored in secondary memory is permanent,
and it is slower than primary memory. A CPU cannot access secondary memory directly. The
data/information from the auxiliary memory is first transferred to the main memory, and then the CPU
can access it.
Characteristics of Secondary Memory
It is a slow memory but reusable.
It is a reliable and non-volatile memory.
It is cheaper than primary memory.
The storage capacity of secondary memory is large.
A computer system can run without secondary memory.
In secondary memory, data is stored permanently even when the power is off.
Types of Secondary Memory
a) Magnetic Tapes: Magnetic tape is a long, narrow strip of plastic film with a thin, magnetic coating on it
that is used for magnetic recording. Bits are recorded on tape as magnetic patches called RECORDS that
run along many tracks. Typically, 7 or 9 bits are recorded concurrently. Each track has one read/write head,
which allows data to be recorded and read as a sequence of characters. It can be stopped, started moving
forward or backward, or rewound.
b Magnetic Disks: A magnetic disk is a circular metal or a plastic plate and these plates are coated with
magnetic material. The disc is used on both sides. Bits are stored in magnetized surfaces in locations called
tracks that run in concentric rings. Sectors are typically used to break tracks into pieces. Hard discs are
discs that are permanently attached and cannot be removed by a single user.
c) Optical Disks: It’s a laser-based storage medium that can be written to and read. It is reasonably priced
and has a long lifespan. The optical disc can be taken out of the computer by occasional users.
d) Floppy Disk: A floppy disk consists of a magnetic disc in a square plastic case. It is used to store data
and to transfer data from one device to another device. Floppy disks are available in two sizes (a) Size: 3.5
inches, the Storage capacity of 1.44 MB (b) Size: 5.25 inches, the Storage capacity of 1.2 MB. To use a
floppy disk, our computer needs to have a floppy disk drive. This storage device becomes obsolete now
and has been replaced by CDs, DVDs, and flash drives.
e) Compact Disc: A Compact Disc (CD) is a commonly used secondary storage device. It contains tracks
and sectors on its surface. Its shape is circular and is made up of polycarbonate plastic. The storage
capacity of CD is up to 700 MB of data. A CD may also be called a CD-ROM (Compact Disc Read-Only
Memory), in this computers can read the data present in a CD-ROM, but cannot write new data onto it.
For a CD-ROM, we require a CD-ROM.
f) Flash Drive: A flash drive or pen drive comes in various storage capacities, such as 1 GB, 2 GB, 4 GB, 8
GB, 16 GB, 32 GB, 64 GB, up to 1 TB. A flash drive is used to transfer and store data. To use a flash drive,
we need to plug it into a USB port on a computer. As a flash drive is easy to use and compact in size,
Nowadays it is very popular.
3. Cache Memory
It is a type of high-speed semiconductor memory that can help the CPU run faster. Between the CPU and
the main memory, it serves as a buffer. It is used to store the data and programs that the CPU uses the
most frequently.
We store information on magnetic disks by recording it magnetically (on two surfaces of the platters)
2. The surface of a platter is divided into circular tracks - which are subdivided into sectors.
3. The set of tracks that are at ONE ARM position make up a cylinder
There are thousands of cylinders in a disk drive, and each track has thousands of sectors.
When the disk is in use, a driver motor spins it at high speed. Typical disks can transfer several megabytes
of data/second, and they have seek times/rotational latencies of several ms.