UNIT -1

FUNDAMENTALS OF COMPUTER

What is Computer:

A computer is an electronic device that can receive, store, process, and output data. It is a
machine that can perform a variety of tasks and operations, ranging from simple
calculations to complex simulations and artificial intelligence.

Basic Introduction to Computer

The history of computers can be traced back to the 19th century when mechanical devices
such as the analytical engine and tabulating machines were developed. However, modern
computers as we know them today were developed in the mid-20th century with the
invention of the transistor and the development of integrated circuits.

Today, computers are widely used in various industries such as education, finance,
healthcare, and entertainment, and they have revolutionized the way we live, work, and
communicate. They have also given rise to a new era of technology such as the internet,
cloud computing, and mobile devices, which have further transformed our daily lives.
Computer is a device that transforms data into meaningful information. It processes the
input according to the set of instructions provided to it by the user and gives the desired
output quickly. A Computer can perform the following set of functions:
 Accept data/input
 Store data
 Process data as desired
 Retrieve the stored data as and when required
 Give the result/output in desired format

Classification of Computers

The computer systems can be classified on the following basis:

1. On the basis of size.

2. On the basis of functionality.
3. On the basis of data handling.

Classification on the basis of size -

1. Super computers: The super computers are the highest performing system. A
supercomputer is a computer with a high level of performance compared to a general-
purpose computer. All of the world’s fastest 500 supercomputers run Linux-based
operating systems. Supercomputers actually play an important role in the field of
computation, and are used for intensive computation tasks in various fields, including
quantum mechanics, weather forecasting, climate research, oil and gas exploration,
molecular modelling, and physical simulations and also throughout the history,
supercomputers have been essential in the field of the cryptanalysis.
Eg: Titan, Jaguar, IBM Roadrunner, PARAM-Siddhi....

2. Mainframe computers: These are commonly called as big iron, they are usually used by
big organisations for bulk data processing. These are widely used as the server as these
systems has a higher processing capability as compared to the other classes of computers.
These are large and powerful computers that are used by large organizations such as
banks, airlines, and government agencies to process massive amounts of data and handle
multiple users simultaneously.
Eg: IBM z Series, System z9 and System z10 servers....

3. Mini computers: These are smaller and less powerful than mainframe computers, but
they are still capable of handling multiple users and processing large amounts of data.
They are commonly used by small to medium-sized businesses for accounting, inventory
management, and other data-intensive tasks. Mini computers that became possible with
the use of transistors and core memory technologies, minimal instructions sets and less
expensive peripherals. They usually took up one or a few inch rack cabinets, compared
with the large mainframes that could fill a room.
Eg: Personal Laptop, PC....

4. Micro computers: A microcomputer is a small, relatively inexpensive computer with a

microprocessor as its CPU. It includes a microprocessor, memory, and minimal I/O
circuitry mounted on a single printed circuit board. The previous to these computers,
mainframes and minicomputers, were comparatively much larger, hard to maintain and
more expensive. They actually formed the foundation for present day microcomputers
and smart gadgets that we use in day to day life. These are small and portable computers
that are designed for on-the-go use,
Eg: Tablets, Smart watches....

Classification on the basis of functionality -

1. Servers: Servers are nothing but dedicated computers which are set-up to offer some
services to the clients. They are named depending on the type of service they offered.
Eg: Security server, Database server.

2. Workstation: Those are the computers designed to primarily to be used by single user at
a time. They run multi-user operating systems. They are the ones which we use for our
day to day personal / commercial work.
Eg: Laptop, Personal computer

3. Information Appliances: They are the portable devices which are designed to perform a
limited set of tasks like basic calculations, playing multimedia, browsing internet etc. They
have very limited memory and flexibility and generally run on “as-is” basis.
Eg: Smartphones and Personal Digital Assistants (PDAs).
4. Embedded computers: They are the computing devices which are used in other
machines to serve limited set of requirements. They follow instructions from the non-
volatile memory and they are not required to execute reboot or reset.
Eg: In-vehicle computers, GPS systems, Fitness trackers, Medical devices, ATMs....

Classification on the basis of data handling -

1. Analog: Analog computers are specifically designed to process analog data. It is a type
of continuous data that continually changes and does not have discrete values. These
types of computers are being used when the users are not familiar with the exact values
like temperature, speed, current, and pressure.
Eg: Speedometer, Tide Predictors, Television, Telephone Lines....

2. Digital: These computers are designed in such a way that they can easily perform
calculations and logical operations at high speed. Such a type of computer takes up raw
data as input and processes it with programs stored in its memory to produce the final
output. A Digital computer only understands the binary input 0 and 1, so the raw input
data is converted to 0 and 1 by the computer and further processed by the computer to
give the result or final output.
Eg: Digital Clock, Weighing Machine, Smart Phones, Laptop/PC, ATM....

3. Hybrid: Hybrid computers are devices that exhibit the features of both digital and
analog computers. These computers have speeds similar to analog computers and are
identical in respect of memory and accuracy to digital computers. Hybrid computers have
the capabilities to process both discrete and continuous data. That is why these devices
have specialized applications where both analog and digital data have to be processed.
Eg: Gasoline Station, Electrocardiogram Machine, Ultrasound machine, CT scan
machine....

Peripheral Devices

These devices are used for performing the specific functions and are connected to the
computer externally. These peripheral devices enable the computer to operate according to
the user requirements by feeding data in and out of the computer. Peripheral devices are:

 Keyboard
 Mouse
 Light Pen
 Optical/magnetic Scanner
 Touch Screen
 Microphone for voice as input
 Track Ball
 Monitor (Visual Display Unit)
 Printers
 Plotter
 Speaker
Block Diagram of a Computer

A Block Diagram of a Computer provides an overview of the major components and their
interactions with each other.

The block diagram represents how data and instructions flow between the CPU, memory,
and I/O devices, managed by the Control Unit. In simple terms, a Block Diagram of a
Computer helps us understand how a computer works, from collecting input data,
processing & formatting the data, and generating the output results in the way user
commands. The computer system consists of three main parts: Input Units, CPU, and Output
Units.

 Step-by-step working of how data is received and displayed on the computer.

Step 1: Input devices allow the users to provide data and commands to the computer. The
data inserted manually is collected by input devices like keyboard, mouse, scanners, and
others. These devices generate electrical signals or data packets representing the input.

Step 2: The data generated by input devices is sent to the computer’s input
interface/memory unit which processes and formats the data for further use by the
computer.

Step 3: The processed input data is then sent to the computer’s Central Processing Unit
(CPU) which temporarily stores this data in memory (RAM) for immediate processing. The
CPU executes instructions related to the input data.

Step 4: After processing, the CPU sends the results or instructions to the computer’s output
interface where the data is formatted for transmission to the output devices.

Step 5: Then the output unit receives the final processed output. Output devices such as
monitors, printers, speakers, and others receive the formatted data. Monitors display visual
information, printers produce hard copies, and speakers play audio, based on the data they
receive.
Explanation for Block Diagram of Computer

There are three main parts of Block Diagram of Computer

1. Input Unit
2. Central Processing Unit (CPU)
3. Output Unit

1. Input Unit
The input unit takes all the data received by the computer. The input unit comprises
different devices such as a mouse, keyboard, scanner, joysticks, webcam, etc. All of these
devices act as intermediaries between the users and the computer. The input unit takes the
data that has to be processed. The raw data is accepted by the computer in binary form.
This data is then processed and the desired output is produced.

The major functions of the Input Unit are-

 The Input Unit takes the data to be processed by the user.
 The data is then converted into machine-readable form.
 The Input Unit then transmits the converted data into the main memory of the
computer.
 The main purpose of this process is to connect the user and the computer by creating
an easy connection between them.

2. Central Processing Unit (CPU)

The Central Processing Unit or CPU is known as the brain of the computer. Just like the
human brain controls all human activities, the CPU also takes care of all the tasks. The CPU is
responsible for performing all the arithmetic and logical operations within the computer. All
the major calculations, operations and comparisons are performed inside the CPU.

Some of the main functions of a CPU are-

 All the components of a computer system, software, and data processing are
controlled by the CPU.
 The Input devices provide data to the CPU which is then executed and then the CPU
sends the output to the Output devices.
 All the operations including the arithmetical and logical are processed by the CPU.

The CPU comprises three parts- ALU (Arithmetic Logic Unit), CU (Control Unit) and MU
(Memory Unit). These units work in sync to help the CPU process the whole data.

 Arithmetic Logic Unit (ALU)

The Arithmetic Logic Unit is comprised of two terms- arithmetic and logic. The two primary
functions that the ALU performs are-

Data is entered into the primary memory via the input unit. Then, the ALU carries out
essential arithmetic operations on this data, including addition, subtraction, multiplication,
and division. After performing all sorts of calculations required on the data, it sends back
data to the storage.
The ALU also performs logical operations such as AND, OR, Equal to, Less than, etc. In
addition, it also handles tasks like merging, sorting, and selecting the given data.

 Control Unit (CU)

As the name suggests, the Control Unit (CU) is the controller of all the activities, tasks and
operations. All these operations are performed inside the computer. The memory unit sends
a set of instructions to the control unit which is then converted by the CU. These
instructions are then converted to control signals. The purpose of these control signals is to
help in prioritizing and scheduling activities. So, the control unit ensures that all tasks inside
the computer work together smoothly, coordinating with the input and output units.

 Memory Unit (MU)

The Memory Unit stores all the data that has to be processed or has been processed. The
memory unit serves as a central hub for all the data. This data is then transmitted to the
required part of the computer whenever necessary. This unit works in sync with the Central
Processing Unit to help in faster accessing and processing of the data. This results in making
the tasks easier and quicker.

Computer Memory is of two types-

Primary memory
Secondary memory

3. Output Unit
Once the information sent to the computer is processed, the user receives the results
through the output unit. Examples of output units are devices such as printer, monitor,
projector, speaker, headphones, etc.

The output unit presents the data either as a soft copy (on the screen) or as a hard copy (on
paper). The printer is for the hard copy. The monitor is for the display. The output unit
receives data in binary form from the computer and converts it into a readable format for
the user.

The major functions of the Output Unit are-

 The Output Unit accepts all the data and information from the main memory of a
computer system in binary form.
 The Output Unit also converts the binary data into a human-readable form for a better
understanding.
Characteristics of a Computer

1. Speed: Computers can perform millions of calculations per second. The computation
speed is extremely fast.
2. Accuracy: Because computers operate on pre-programmed software, there is no space for
human error.
3. Diligence: They can perform complex and long calculations at the same time and with the
same accuracy.
4. Versatile: Computers are designed to be versatile. They can carry out multiple operations
at the same time.
5. Storage: Computers can store a large amount of data/ instructions in its memory, which
can be retrieved at any point of time.

Computer and its components:

The computer has mainly two major components:

 Hardware
 Software

 Hardware

Computer hardware is a physical device of computers that we can see and touch. For
example Monitor, Central Processing Unit, Mouse, Joystick, etc. Using these devices, we can
control computer operations like input and output.

Types of Hardware in Computer:

These hardware components are further divided into the following categories, which are:
1. Input Devices
2. Output Devices
3. Storage Devices
4. Internal Components

1. Input Devices
An input device is a computer device or hardware component of a computer system that
allows the user to provide data, input, instructions to the computer system.
Examples - Keyboard, Mouse, Scanner, Track Ball, Light Pen, Microphone, Bar Code
Reader....
2. Output Devices
An output device is a computer device or hardware component of a computer system that
gives information to users in the form of text, visuals, audio or a hard copy (printed on
paper).
Examples - Monitor, Printer, Plotter, Speakers, Projector....

3. Storage Devices
A storage device is an integral part of the computer hardware which stores
information/data to process the result of any computational work.

Storage Devices are two types-

o Primary storage devices: They are fit internally to the computer and very fast in terms
of accessing data files. The RAM and cache memory are the examples of the primary
storage devices.

o Secondary storage devices: The hard disk, USB storage devices and optical disk drive are
examples of secondary storage devices, which are designed to store data permanently.
They include a large storage capacity while comparing with primary storage devices.

Examples - CD (Compact disc), DVD (Digital Video/Versatile Disc), Hard Disk....

4. Internal Components
Some important hardware devices/components which are present in computer internally
usually we cannot see are known as the internal components
Examples - CPU (Central Processing Unit) parts, Motherboard, Video Graphics Array Port
(VGA), Power Supply Cord, Cooling Fan....

 Software

Software is a collection of instructions, data, or computer programs that are used to run
machines and carry out particular activities.

Types of Software in Computer

1. System Software
o Operating System
o Language Processor
o Device Driver

2. Application Software
o General Purpose Software
o Customize Software
o Utility Software
1. System Software
System Software is a component of Computer Software that directly operates with
Computer Hardware

o Operating System
It is the main program of a computer system. When the computer system ON it is the first
software that loads into the computer’s memory. Basically, it manages all the resources and
provides an interface to the user, which helps the user to interact with the computer
system.
Examples – Linux, Apple mac OS, Microsoft Windows, etc.

o Language Processor
As we know that system software converts the human-readable language into a machine
language and vice versa. So, the conversion is done by the language processor.
Examples –
 Assembler
 Interpreter
 Compiler

o Device Driver
A device driver is a program or software that controls a device and helps that device to
perform its functions. Every device like a printer, mouse, modem, etc. needs a driver to
connect with the computer system eternally

2. Application Software
Application Software is the software that works the basic operations of the computer. It
performs a specific task for users.

o General Purpose Software

This type of application software is used for a variety of tasks and it is not limited to
performing a specific task only.
For example - MS-Word, MS-Excel, MS PowerPoint, etc.

o Customize Software
This type of application software is used or designed to perform specific tasks or functions
or designed for specific organizations.
For example - Railway reservation system, Airline reservation system, Invoice management
system, etc.

o Utility Software
This type of application software is used to support the computer infrastructure. It is
designed to analyze, configure, optimize and maintains the system, and take care of its
requirements as well.
For example - Antivirus, Disk fragmenter, Memory tester, Disk repair, Disk cleaners, Registry
cleaners, Disk space analyzer, etc.
Firmware
Firmware is a form of microcode or program embedded into hardware devices to help them
operate effectively. Hardware like cameras, mobile phones, network cards, optical drives,
printers, routers, scanners, and television remotes rely on firmware built into their memory
to function smoothly. Firmware is nothing but "Software for Hardware". Firmware software
programs cannot be changed and they won’t be erased when there is no power supply.

However, there is a difference between firmware and software. Firmware provides

instructions to help hardware start up, communicate with other devices, and perform basic
input/output tasks. Software, on the other hand, is installed onto a device and used for
interaction, such as browsing the internet, word processing, listening to music, and
videoconferencing.

There are two types of firmware that can be serviced -

 System firmware: By controlling the flow of instructions and data between the
hardware and software components.
 Device firmware: Device firmware is associated with a particular device integrated into
a system.

Programming Language
A programming language defines a set of instructions that are compiled together to
perform a specific task by the CPU (Central Processing Unit). The programming language
mainly refers to high-level languages such as C, C++, Pascal, Ada, COBOL, etc.

Programming Language fall into three levels/categories -

Machine-level language
The machine-level language is a language that consists of a set of instructions that are in
the binary form 0 or 1. As we know that computers can understand only machine
instructions, which are in binary digits, i.e., 0 and 1, so the instructions given to the
computer can be only in binary codes.
Creating a program in a machine-level language is a very difficult task as it is not easy for
the programmers to write the program in machine instructions. It is error-prone as it is not
easy to understand, and its maintenance is also very high. A machine-level language is not
portable as each computer has its machine instructions, so if we write a program in one
computer will no longer be valid in another computer.

Assembly Language
The assembly language contains some human-readable commands such as mov, add, sub,
etc. The problems which we were facing in machine-level language are reduced to some
extent by using an extended form of machine-level language known as assembly language.
Since assembly language instructions are written in English words like mov, add, sub, so it is
easier to write and understand.
These short codes are called as Mnemonics.
High-Level Language
The high-level language is a programming language that allows a programmer to write the
programs which are independent of a particular type of computer. The high-level languages
are considered as high-level because they are closer to human languages than machine-
level languages.
When writing a program in a high-level language, then the whole attention needs to be
paid to the logic of the problem.
A compiler is required to translate a high-level language into a low-level language.

Characteristics of a Programming Language -

 A programming language must be simple, easy to learn and use, have good
readability, and be human recognizable.
 A portable programming language is always preferred.
 A programming language should be well structured and documented so that it is
suitable for application development.
 A programming language should provide a single environment known as Integrated
Development Environment (IDE).
 A programming language must be consistent in terms of syntax and semantics.

Basic Terminologies in Programming Languages -

 Algorithm: A step-by-step procedure for solving a problem or performing a task.
 Variable: A named storage location in memory that holds a value or data.
 Data Type: A classification that specifies what type of data a variable can hold, such as
integer, string, or boolean.
 Function: A self-contained block of code that performs a specific task and can be
called from other parts of the program.
 Control Flow: The order in which statements are executed in a program, including
loops and conditional statements.
 Syntax: The set of rules that govern the structure and format of a programming
language.
 Comment: A piece of text in a program that is ignored by the compiler or interpreter,
used to add notes or explanations to the code.
 Debugging: The process of finding and fixing errors or bugs in a program.
 IDE: Integrated Development Environment, a software application that provides a
comprehensive development environment for coding, debugging, and testing.
 Operator: A symbol or keyword that represents an action or operation to be
performed on one or more values or variables, such as + (addition), – (subtraction), *
(multiplication), and / (division).
 Statement: A single line or instruction in a program that performs a specific action or
operation.

Advantages of programming languages:

o Increased Productivity: Programming languages provide a set of abstractions that
allow developers to write code more quickly and efficiently.
o Portability: Programs written in a high-level programming language can run on many
different operating systems and platforms.
 o Readability: Well-designed programming languages can make code more readable and
easier to understand for both the original author and other developers.
o Large Community: Many programming languages have large communities of users and
developers, which can provide support, libraries, and tools.
o Disadvantages of programming languages:
o Complexity: Some programming languages can be complex and difficult to learn,
especially for beginners.
o Performance: Programs written in high-level programming languages can run slower
than programs written in lower-level languages.
o Limited Functionality: Some programming languages may not have built-in support for
certain types of tasks or may require additional libraries to perform certain functions.
o Fragmentation: There are many different programming languages, which can lead to
fragmentation and make it difficult to share code and collaborate with other
developers.

Disadvantages of programming languages:

o Complexity: Some programming languages can be complex and difficult to learn,
especially for beginners.
o Performance: Programs written in high-level programming languages can run slower
than programs written in lower-level languages.
o Limited Functionality: Some programming languages may not have built-in support for
certain types of tasks or may require additional libraries to perform certain functions.
o Fragmentation: There are many different programming languages, which can lead to
fragmentation and make it difficult to share code and collaborate with other
developers.

Computer Memory
Computer memory is the storage space in the computer, where data is to be processed and
instructions required for processing are stored.

Types of Computer Memory

 Primary Memory/Main memory/Internal memory
 Secondary Memory/External memory/Auxiliary memory
 Tertiary Memory

Computer Storage Device

The storage unit is a part of the computer system which is employed to store the
information and instructions to be processed. Without a storage device, a computer would
not be able to run or even boot up. Or in other words, we can say that a storage device is
hardware that is used for storing, porting, extracting data files. It can also store
information/data both temporarily and permanently.

Types of Computer Storage Devices related to Computer Memory -

1. Primary Storage Device: These are the devices that store data temporarily and are
directly accessible by the CPU. They include RAM (Random Access Memory) and ROM (Read
Only Memory). RAM is volatile, meaning it loses its data when the power is turned off, while
ROM is non-volatile, meaning it retains its data even when the power is off. RAM is used to
store information that is currently being processed by the computer, while ROM is used to
store firmware and basic instructions for booting up the computer.

2. Secondary Storage Device: These are the devices that store data permanently and are
not directly accessible by the CPU. They include Hard Disks, CDs, DVDs, Pen/Flash drives,
SSD, etc. These devices have larger capacities and lower costs than primary storage devices,
but they are slower and require more power. They are used to store programs, files, and
backup data that are not frequently accessed by the computer.

3. Tertiary Storage Device: These are the devices that store data automatically without
human intervention. They include tape drives, cloud storage, etc. These devices have a very
large capacity and low cost, but they are very slow and require special software and
hardware to access. They are used to store archival data that are rarely accessed by the
computer.

Types of Computer Storage Devices

Now we will discuss different types of storage devices available in the market. These storage
devices have their own specification and use. Some of the commonly used storage devices
are:
i. Primary Storage Devices
ii. Magnetic Storage Devices
iii. Flash Memory Devices
iv. Optical Storage Devices
v. Cloud and Virtual Storage

i. Primary Storage Devices

Primary storage devices are the components of a computer system that store data and
instructions temporarily while the processor executes them.

RAM (Random Access Memory): It is a hardware device generally located on the

motherboard of a computer and acts as an internal memory of the CPU.

o DRAM (dynamic random access memory): This is the most common type of primary
storage device in modern computers. It consists of millions of tiny capacitors that store
bits of data as electrical charges. DRAM needs to be refreshed periodically to maintain
its data. Some types of DRAM are SDRAM (synchronous DRAM), DDR (double data rate),
and RDRAM (Rambus DRAM).

o SRAM (static random access memory): This is a faster and more expensive type of
primary storage device than DRAM. It consists of millions of tiny transistors that store
bits of data as on/off states. SRAM does not need to be refreshed, but it consumes
more power than DRAM. Some types of SRAM are L1 cache, L2 cache, and register files.
ROM (Read-Only Memory): This is a type of primary storage device that stores data and
instructions permanently and cannot be modified. It is used to store the basic input/output
system (BIOS) and other firmware that control the hardware and boot process of the
computer.

o PROM: PROM is Programmable Read-Only Memory. These are ROMs that can be
programmed. A special PROM programmer is employed to enter the program on the
PROM. Once the chip has been programmed, information on the PROM can’t be
altered. PROM is non-volatile, that is data is not lost when power is switched off.

o EPROM: Another sort of memory is the Erasable Programmable Read-Only Memory. It

is possible to erase the info which has been previously stored on an EPROM and write
new data onto the chip.

o EEPROM: EEPROM is Electrically erasable programmable read-only memory. Here, data

can be erased without using ultraviolet light, with the use of just applying the electric
field.

Cache Memory: This is a small and fast type of primary storage device that stores frequently
used data and instructions close to the processor. It reduces the access time and improves
the performance of the computer. Cache memory can be divided into levels (L1, L2, L3)
depending on their size and speed. L1 cache is the fastest and smallest, located inside the
processor chip. L2 cache is larger and slower than L1 cache, located either inside or outside
the processor chip. L3 cache is the largest and slowest level of cache, located outside the
processor chip.

ii. Magnetic Storage Devices

A magnetic storage device is a device that uses a magnetic medium to store data.

Hard disk drive (HDD): A hard disk drive consists of one or more rigid metal platters coated
with a thin layer of magnetic material. The platters spin at high speeds and are accessed by
read/write heads attached to an arm that moves across the surface of the platters. The
read/write heads generate or detect magnetic fields to read or write data on the platters.

Floppy disk: A floppy disk is a flexible plastic disk coated with a thin layer of magnetic
material. The disk is inserted into a floppy disk drive that has a read/write head that moves
across the surface of the disk. The read/write head generates or detects magnetic fields to
read or write data on the disk.

Magnetic tape: A magnetic tape is a long strip of plastic film coated with a thin layer of
magnetic material. The tape is wound on a spool and is moved past a read/write head that
generates or detects magnetic fields to read or write data on the tape.

Zip disk: A zip disk is similar to a floppy disk, but has a higher storage capacity and faster
data transfer rate. The zip disk is inserted into a zip drive that has a read/write head that
moves across the surface of the disk. The read/write head generates or detects magnetic
fields to read or write data on the disk.
Magnetic stripe cards: Magnetic stripe cards are used to store data on a thin strip of
magnetic material. Magnetic stripe cards are often used for identification and access control
purposes.

Magnetic drums: Magnetic drums are a type of magnetic storage device that uses a rotating
cylinder coated with a magnetic material. Magnetic drums were once popular for storing
large amounts of data, but they have been largely replaced by other types of storage
devices.

Magnetic cards: Magnetic cards are a type of magnetic storage device that uses a thin,
flexible card coated with a magnetic material. Magnetic cards are often used for storing
credit card numbers, identification numbers, and other personal information.

Magnetic bubble memory: Magnetic bubble memory is a type of magnetic storage device
that uses tiny magnetic bubbles to store data. Magnetic bubble memory was once
considered a promising technology, but it was never widely adopted.

Magnetic random-access memory (MRAM): MRAM is a type of non-volatile magnetic

memory that uses a ferromagnetic material to store data. MRAM is still under development,
but it has the potential to replace traditional DRAM memory.

iii. Flash Memory Devices

Flash Memory Devices are devices that use EEPROM technology, which allows them to write
and erase data by applying electrical signals.

USB Drive: Also referred to as a USB flash drive, pen drive, keychain drive, memory unit,
thumb drive, or a jump drive is a transportable storage device. A USB drive is generally small
in size and can be connected to a computer via a USB port. It has a storage range between 2
GB to 1 TB. It comprises an integrated circuit that enables the USB drive to store and replace
data.

SD cards: SD cards are small, removable memory cards that are often used in digital
cameras, smartphones, and other portable devices.

CompactFlash cards: CompactFlash cards are larger and more durable than SD cards. They
are often used in professional digital cameras and other devices that require high-capacity
storage.

Memory sticks: Memory sticks are a type of flash memory that is used in laptops and other
devices. They are similar to USB flash drives, but they are typically larger and have a higher
capacity.

Solid-state drives (SSDs): SSDs are a type of flash memory that is used in computers instead
of traditional hard drives. SSDs are faster and more durable than hard drives, but they are
also more expensive.
Multimedia Card: It is also known as MMC. It is an integrated circuit that is generally used
in-car radios, digital cameras, etc. It is an external device to store data/information.

iv. Optical Storage Devices

Optical storage devices are devices that use light to store and retrieve data.

Compact Disc (CD): CDs are the most common type of optical storage device. They were first
introduced in 1982 and are used to store music, movies, and data files. CDs have a storage
capacity of up to 700MB.
CD-R: It stands for Compact Disc read-only.
CD-RW: It stands for Compact Disc Read Write.

Digital Versatile Disc (DVD): DVDs were introduced in 1996 and are high-capacity optical
storage devices. They can store up to 4.7GB of data, which is enough to store a full-length
movie.
DVD-R: It stands for Digital Versatile Disc read-only.
DVD-RW: It stands for Digital Versatile Disc Read Write.

Blu-ray Disc (BD): BDs were introduced in 2006 and are high-definition optical storage
devices. They can store up to 128GB of data, which is enough to store multiple full-length
movies.

Holographic Versatile Disc (HVD): HVDs are a new type of optical storage device that is still
under development. They have the potential to store up to 1TB of data, which is enough to
store thousands of full-length movies.

v. Cloud and Virtual Storage

Cloud storage: The term Cloud computing is related to the data centres available for users
over the Internet where they can collect their databases and files. It offers users reliability,
durability, confidentiality, and access to data or information from anywhere and anytime.
The requirement to store data online and in cloud storage is growing rapidly.

 Concept of Cache Memory

A faster and smaller segment of memory whose access time is as close as registers are
known as Cache memory. In a hierarchy of memory, cache memory has access time lesser
than primary memory. Generally, cache memory is very small and hence is used as a buffer.

Data in primary memory can be accessed faster than secondary memory but still, access
times of primary memory are generally in a few microseconds, whereas the CPU is capable
of performing operations in nanoseconds. Due to the time lag between accessing data and
acting on data performance of the system decreases as the CPU is not utilized properly, it
may remain idle for some time. In order to minimize this time gap new segment of memory
is Introduced known as Cache Memory.
Role of Cache Memory
 Cache memory plays a crucial role in computer systems.
 It provide faster access.
 It acts buffer between CPU and main memory(RAM).
 Primary role of it is to reduce average time taken to access data, thereby improving
overall system performance.

Benefits of Cache Memory

 Faster access
 Reducing memory latency
 Lowering bus traffic
 Increasing effective CPU utilization
 Enhancing system scalability

Types of Cache Memory -

L1 or Level 1 Cache: It is the first level of cache memory that is present inside the processor.
It is present in a small amount inside every core of the processor separately. The size of this
memory ranges from 2KB to 64 KB.

L2 or Level 2 Cache: It is the second level of cache memory that may present inside or
outside the CPU. If not present inside the core, It can be shared between two cores
depending upon the architecture and is connected to a processor with the high-speed bus.
The size of memory ranges from 256 KB to 512 KB.

L3 or Level 3 Cache: It is the third level of cache memory that is present outside the CPU and
is shared by all the cores of the CPU. Some high processors may have this cache. This cache
is used to increase the performance of the L2 and L1 cache. The size of this memory ranges
from 1 MB to 8MB.
Generations of Computer:
The computer generations are classified into five generations. They are –

 First Generation Computers

The technology behind the primary generation computers was a fragile glass device, which
was called a vacuum tube. These computers were very heavy and really large. These weren’t
very reliable and programming on them was a tedious task as they used low-level
programming language and used no OS. First-generation computers were used for
calculation, storage, and control purpose. They were too bulky and large that they needed a
full room and consume a lot of electricity.

 Second Generation Computers

Second-generation computers used the technology of transistors rather than bulky vacuum
tubes. Another feature was the core storage. A transistor may be a device composed of
semiconductor material that amplifies a sign or opens or closes a circuit.

Transistors were invented in Bell Labs. The use of transistors made it possible to perform
powerfully and with due speed. It reduced the dimensions and price and thankfully the
warmth too, which was generated by vacuum tubes. Central Processing Unit (CPU),
memory, programming language, and input, and output units also came into the force
within the second generation.

The programming language was shifted from high level to programming language and made
programming comparatively a simple task for programmers. Languages used for
programming during this era were FORTRAN (1956), ALGOL (1958), and COBOL (1959).
  Third Generation Computers
During the third generation, technology envisaged a shift from huge transistors to
integrated circuits, also referred to as IC. Here a variety of transistors were placed on silicon
chips, called semiconductors. The most feature of this era’s computer was speed and
reliability. IC was made from silicon and also called silicon chips.

A single IC has many transistors, registers, and capacitors built on one thin slice of silicon.
The value size was reduced and memory space and dealing efficiency were increased during
this generation. Programming was now wiped out Higher level languages like BASIC
(Beginners All-purpose Symbolic Instruction Code). Minicomputers find their shape during
this era.

 Fourth Generation Computers

In 1971 First microprocessors were used, the large-scale of integration LSI circuits built on
one chip called microprocessors. The advantage of this technology is that one
microprocessor can contain all the circuits required to perform arithmetic, logic, and control
functions on one chip.
The computers using microchips were called microcomputers. This generation provided
even smaller size of computers, with larger capacities. That’s not enough, then Very Large
Scale Integrated (VLSI) circuits replaced LSI circuits. The Intel 4004 chip, developed in 1971,
located all the components of the pc from the central processing unit and memory to input/
output controls on one chip and allowed the dimensions to reduce drastically.

Technologies like multiprocessing, multiprogramming, time-sharing, operating speed, and

virtual memory made it a more user-friendly and customary device. The concept of private
computers and computer networks came into being within the fourth generation.

 Fifth Generation Computers

The technology behind the fifth generation of computers is AI. It allows computers to
behave like humans. It is often seen in programs like voice recognition, area of medicine,
and entertainment. Within the field of game playing also it’s shown remarkable
performance where computers are capable of beating human competitors.

The speed is the highest, size is the smallest and area of use has remarkably increased
within the fifth generation computers. Though not a hundred percent AI has been achieved
to date but keeping in sight the present developments, it is often said that this dream also
will become a reality very soon.