UNIT 2: COMPUTER SYSTEMS AND

SMART DEVICES
Structure
2.1 Introduction
2.2 Objectives
2.3 Components of a computer
2.4 Central Processing Unit (CPU)
2.5 Storage and storage devices
2.6 I/O devices
2.7 Networking and networking devices
2.8 Plug and play devices
2.9 Smart Devices
2.10 Communication technology
2.11 Types of computer
2.12 Summary
2.13 Unit End exercises
2.14 References and Suggested Further Readings

2.1 INTRODUCTION
For an information system, hardware is defined as any machinery that helps
in input, processing, storage, and output activities. Similarly for a computer,
the hardware is the collection of devices that perform the functions of input,
processing, data storage, and output. In other words, all physical units of a
computer system constitute computer hardware. The input device gets the
data from the outside world and the data is stored in the memory. The central
processing unit (CPU) processes this data and the various output devices
provide the results. The components communicate with each other through
system bus. Each hardware component plays an important role in computing.
The arrangement of the component within the system even today is what
was suggested in 1945 as stored program concept of computing by Von
Neumann and is known as Von Neumann architecture. Smart devices use
internet or the organizational network and work as information processors
and information providers. A smart device is an electronic device, generally
connected to other devices or networks via different wireless protocols
such as Bluetooth, Wi-Fi etc., that can operate to some extent interactively
and autonomously. They can be used in almost any industry, from smart
manufacturing to healthcare, helping to improve efficiency and optimize
operations.

2.2 OBJECTIVES
After reading this unit you should be able to:
●● Identify the components of a computer system;
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●● Describe the elements of a CPU; Computer Systems and
Smart Devices
●● Explain the concept of networking;
●● Use plug and play devices; and
●● Understand about smart devices.

2.3 COMPONENTS OF A COMPUTER

Input
Devices Central Processing Unit

Arithmetic Control Communication

& Unit Devices
Logic Unit

Output
Primary Storage Devices

Secondary Storage

Fig 2.1: Components of a Computer

The computer memory is categorized into primary storage and secondary

storage. Primary storage stores the data and programs during processing
and secondary storage is used to store the data and programs for future
use. Communication devices connect a computer to other computers and
devices to facilitate data exchange with them.
Computers have been around since 1940s and have been evolving ever
since. Computer hardware has mainly evolved through four stages.
The so-called first generation (1946-1956) computer was built by vacuum
tubes and programming was done by plugging and unplugging chords.
The second-generation (1957-1963) computers had transistors. The third
generation (1964-1979) computers had Integrated Circuits (ICs). The fourth
generation (1979 onwards) systems use Very Large-Scale Integrated (VLSI)
circuits. Along with the hardware technology, the software also improved in
terms of being user friendly and capability. Every system has software as its
integral part, which makes the computer work. The most important software
is an operating system (OS), which performs two functions:
●● Extend the machine - OS presents to the user an extended machine
that is easier to program than the underlying hardware.
●● Manage resources such as processor(s), memories, timers, disks,
mouse, network, printer etc. OS provides an orderly and controlled
allocation of the resources among the various programs competing
for them.

2.4 CENTRAL PROCESSING UNIT

In order to work, a computer needs some sort of “brain”. At the core of each
computer, there is a device called central processing unit (CPU), which is
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Information Technology the brain of the computer. CPU reads the program from the main memory,
for Managers and executes each step of the program, which may involve calculations and
decision-making. The CPU is responsible for controlling all devices of the
computer through it’s component – the Control Unit. It initiates a memory
operation, which may involve reading data from an input device and storing
it into memory or read data from the memory and display it on an output
device.
The CPU mainly consists of three parts- Control Unit, Arithmetic and Logic
Unit (ALU), and it’s storage also referred to as the CPU registers.
The ALU is the unit, which performs all mathematical calculations and
logical operations. It performs addition, subtraction, multiplication, and
division. It performs a logical operation by comparing two numbers. It
can determine the smaller number, larger number or determine if the two
numbers are equal. It can also determine whether a number is positive,
negative or zero.
A program is a sequence of instructions. An instruction may be an arithmetic
operation, a logical operation, an assignment, or a jump. The control unit
sequentially accesses program instructions, decodes them, and directs ALU,
Main Memory also referred to as Primary Storage, input devices, and output
devices so that the program instructions can be carried out. Execution of
one program instruction may require control unit to issue many directives.
The ALU may also perform many operations to complete one program
instruction. Each operation performed by ALU and control unit is referred
to as machine instruction. Each program instruction may involve many
machine instructions. A single machine instruction is completed in a
machine cycle. The number of machine instructions completed in a second
is called the speed of the CPU and it is measured in MIPS (Millions of
Instructions Per Second) or BIPS (Billions of Instructions Per second). A
CPU also contains a set of registers, which are specialized, small, high-
speed memory for storing temporary results of ALU and for storing control
information.
Computer Speed
The word length of a CPU is the number of bits it can process in a single
cycle. A 64-bit machine can process 64 bits in a single cycle. A 64-bit
machine is faster than a 32-bit machine. Today as faster as 256 bit processors
are available which are much faster than what we used to have earlier.
The cycle is defined by the internal clock of the control unit. We have
systems with as much as 5.1 GHz (Giga Hertz). Intel Core i7 & Core i9
based systems provide this speed. Similarly it may be available with other
manufacturers like AMD also. In yester years, systems used to be with KHz
(Kilo Hertz) and MHz (Mega Hertz).
The bus carries data, control signals, and address in a system. If the data bus
width is same as the word length, then one word can be moved at a time.
If the bus width is half of word length, two cycles are required for moving
one word.
The instruction set also affects the speed. If the instruction set is simple,
as in RISC (Reduced Instruction Set Computers), one or more instructions
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may get executed in each cycle. There will be some long instructions, which Computer Systems and
take more than one cycle. It is possible that a given application extensively Smart Devices
uses long instructions (such as scientific computing) and the machine will
appear to be slow.
There is no direct relationship between clock frequency and the speed of a
system. There are benchmark programs that are run to establish the speed
of a computer system.

2.5 STORAGE AND STORAGE DEVICES

The large amount of data is stored on a computer using various types of
storage media. The storage media are distinguished by their relative speed,
capacity, and resilience to failure.
1) Volatile Storage: Information residing in such storage needs
continuous power supply. The contents are lost if power supply is
switched off. Examples of such storage devices are main memory and
cache memory, which we will discuss in the next section. Access to
volatile storage is very fast, both because of the technology used and
because of the access method.
2) Nonvolatile Storage: The nonvolatile storage media do not require
power supply to retain their contents. Examples of such storage media
are disks and magnetic tapes. Disk is used for online storage, while
tapes are used for archival storage. Disks and magnetic tapes are very
reliable storage media. The current technology used for nonvolatile
storage makes them much slower than volatile storage.
Main Memory
Main memory holds the programs and data required by the CPU for
carrying out its operations. The primary storage is a semiconductor device
that is built using integrated circuits. The data is stored in binary form by
main memory. Numeric as well as non-numeric data can be represented in
binary form. With two binary digits, we can represent 4 different characters.
With three binary digits, we can represent 8 different characters. Computes
internally use eight binary digits to represent characters and digits (A binary
digit is referred to as bit and 8 bits are called a byte). 256 characters can
be represented by a byte. The main memory consists of many thousands of
bytes. The table given below lists commonly used names, abbreviations and
the number of bytes for storage capacity.
Table 2.1: Commonly Used Names and Abbreviations for Storage Capacity
NAME ABBREVIATION NUMBER OF BYTES
Byte B 1
Kilobyte KB 1,024
Megabyte MB 1,024 * 1,024 (about one million)
Gigabyte GB 1,024 * 1,024 * 1,024
Terabyte TB 1,024 * 1,024 * 1,024 * 1,024

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Information Technology Types of Main Memory
for Managers
Memory can be of various types like Random Access Memory (RAM) and
Read-Only Memory (ROM). The figure 2.2 given below gives a description
of the memory types.

Memory Types

Random Read
Access Only
Memory Memory
(RAM) (ROM)

SDRAM DRAM EPROM PROM

Figure 2.2: Types of Memory

RAM has become the synonym for main memory. Earlier, the word core
memory was used for referring to main memory. RAM is the memory
access method and core memory was the technology used in main memory.
The core memory technology is not used any more. RAM is an acronym
for Random Access Memory. As the name suggests, any location of the
memory can be accessed randomly and the access time to is independent of
the location. We will continue to use word RAM to refer to main memory.
RAM is very fast; the access time is in nano seconds. RAM is volatile that
is the contents of RAM are lost when the power supply to the RAM is
discontinued.
DRAM (Dynamic Random Access Memory) has been the most common
kind of RAM. The data is stored in the cell of transistors and capacitors
and the data has to be refreshed every few milliseconds. SRAM (Static
Random Access Memory) does not require periodical refresh. SRAM is
faster than DRAM but is more expensive as compared to DRAM. SDRAM
(Synchronous DRAM) is used these days. In fact the first version of
SDRAM which is also known as DDR (Double Data Rate) RAM came in
1998. Further advancements in DDR have gone up to DDR5 (July 2020)
which has capacity of double the capacity of DDR4 i.e. 2x21.3GB, the
DDR4 being of 21.3GB.
A part of computer storage is ROM that cannot be erased or changed. ROM
is an acronym for read only memory. ROM is nonvolatile i.e. its contents are
not lost when power is switched off. ROM is required for storing the boot
program that should not be lost or changed due to any failure. ROM also
comes in many flavors such as PROM and EPROM. PROM (Programmable
Read Only Memory) is used for storing some specialized application by the
computer designers instead of chip designers. PROM can be written only
once. EPROM (Erasable Programmable Read Only Memory) can be erased
and reprogrammed many times.

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Secondary Memory Computer Systems and
Smart Devices
Main Memory provides a small amount of volatile storage. But a computer
needs to store large amount of data and instructions permanently. The
secondary memory is non-volatile and has large capacity. The secondary
memory is slow as compared to main memory. Various technologies are used
for secondary memory, some provide random access, and others provide
sequential access. In sequential access, data must be accessed in the order
in which it is stored. For example, if we have stored data of students in the
order of their roll numbers, then to retrieve data of student with roll number
20, we need to read (and possibly discard) the data of students with roll
numbers 01 to 19 before we can access the desired data. If direct access is
provided then any part of the data can be accessed directly, without the need
to pass by other data in sequence. The sequential access storage devices are
referred to as SASD (Sequential Access Storage Devices) and the direct
access devices are called DASDs (Direct Access Storage Devices). The
most common forms of secondary storage devices are magnetic tapes and
magnetic disks.
Magnetic tape is one of the common sequential secondary storage mediums.
The tape usually is a Mylar film coated with iron oxide. Portions of the tape
are magnetized to represent bits. It is sequential access device, to access the
nth block on tape; we must first read the preceding n-1 blocks. The main
advantages of the magnetic disks are that they are inexpensive, long lasting
and can store large volume of data (in Tera Bytes). Generally it is used for
back up or archival storage of data.
Magnetic Disk is all made of magnetic material shaped as a thin circular
disk and protected by a plastic or acrylic cover. A disk is single sided if
it stores information on only one of its surfaces and double sided if both
surfaces are used. To increase storage capacity, disks are assembled into
a disk pack, which may include many surfaces. Information is stored on
the disk surface in concentric circles of small width, each having a distinct
diameter. Each circle is called a track. For disk packs, the tracks with the
same diameter on the various surfaces are called a cylinder. The concept of
cylinder is very important because data stored on the same cylinder can be
retrieved much faster than if it were distributed among different cylinders.
Each concentric circle typically stores the same amount of data. The number
of tracks on a disk ranges up to 1023. Each track is divided into sectors. A
sector can store up to 4KB, available in laptop computers The division of a
track into equal sized blocks or pages is set by the operating system during
disk formatting. There is a read/write head, which reads data from the disk
and writes data to the disk. A disk is mounted on the disk drive, which has
the motor that rotates it. A read/write head has a mechanical arm attached to
it. All arms are connected to an actuator attached to another electrical motor,
which moves the head in unison and positions it over the cylinder of tracks
specified in a block address.
RAID (Redundant Array of Independent Disks) is an array of multiple
inexpensive hard disks that provides fault tolerance through redundancy and
improved access rates. It provides a method of accessing multiple individual
disks, as they are one large disk. The data is spread over these multiple
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Information Technology disks, thereby reducing the risk of losing all data if one disk fails. Usually,
for Managers RAID is used in a computer, which is a file server or a transaction server,
where data accessibility is critical and fault tolerance is required. RAID is
also used in desktop systems for CAD, multimedia editing, and playback
systems where higher transfer rates are needed. RAID levels storage can be
used for three distinct purposes, including:
Capacity: Capacity is a simple one that is especially involved in most
every type of RAID setup used. For example, two hard drives can be linked
together as a single drive to the OS effectively making a virtual drive that
is twice the capacity.
Security: RAID levels can be used for data security by using some of the
space on the drives to essentially clone the data that is written to both drives.
Once again, with two drives you can make it so that the data is written to
both drives.
Performance: Performance is another key reason for using a RAID setup
on a personal computer. Also, RAID levels can be used for data security by
using some of the space on the drives to essentially clone the data that is
written to both drives. Once again, with two drives you can make it so that
the data is written to both drives.
The RAID has following levels:
1) RAID 0: It is also known as “Disk Striping”. This is technically not
a RAID level since it provides no fault tolerance. Data is written
in blocks across multiple drives for fast access. The advantages of
striping are the higher access rate, and full utilization of the array
capacity. The disadvantage is there is no fault tolerance
2) RAID 1: This is also known as “Disk Mirroring”. Raid 1 provides
redundancy by writing the data twice. If one disk fails, the other contains
an exact duplicate of the data and the RAID can switch to using the
mirror drive with no lapse in user accessibility. The disadvantages of
mirroring are no improvement in data access speed, and higher cost,
since twice the number of drives is required. However, it provides
the best protection of data since the array management software will
simply direct all application requests to the surviving disk members
when a member of disk fails.
3) RAID 2: In this type of RAID set up disk striping occurs at the bit-level.
RAID 2 is seldom deployed because cost to implement are usually
high as a typical set up requires 10 disks and gives poor performance
with some I/O operations.
4) RAID 3: RAID level 3 distribute data across multiple discs and stores
additional information on one disc for error correction in recovery. It
has high reliability and it is fast.
5) RAID 4: RAID 4 is a configuration in which disk striping happens at
the byte level rather than bit level as in RAID 3.
6) RAID 5: It is the most popular configuration. In RAID 5, the
additional data, which is used for error detection and correction, is
also distributed over many discs. This arrangement has very high
reliability and access speed is also good. However, the write operation
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 is slower compared to other RAID configurations. Computer Systems and
Smart Devices
7) RAID 6: RAID 6 is also used frequently in enterprises. It is identical
to RAID 5 except that it is an even more robust because it uses one
more parity block that RAID 5. You can have two disks non-functional
(dead) and still have a system be operational.
There are further RAID levels possible but above are sufficient for your
knowledge.
Optical Disks are the disks made of plastic, in which lasers that physically
burn pits in the disk record data. Here each pit represents a binary digit 1 and
each unpitted area represents binary digit 0. Optical discs are direct access
devices. The advantage of optical disks are that the amount of physical disk
space needed to record an optical bit is much smaller than usually required
by magnetic media and is less susceptible to deterioration.
Cache
It is high-speed memory and expensive. The CPU keeps part of the program
and the data into cache memory, which it is likely to use frequently. Cache
plays a direct role in increasing Internet speed than RAM does. RAM and
cache are both a form of computer memory. Cache stores images and text
from web pages as you view them. Pages in cache are not updated while
RAM refreshes it again and again.
Traditionally, Cache is categorized as “levels” that describe its closeness
and accessibility to the microprocessor. There are three general cache
levels: L1 cache, or primary cache, is extremely fast but relatively small,
and is usually embedded in the processor chip as CPU cache. L2 cache,
or secondary cache, is often more capacious than L1. L2 cache may be
embedded on the CPU, or it can be on a separate chip or coprocessor and
have a high-speed alternative system bus connecting the cache and CPU.
That way it doesn’t get slowed by traffic on the main system bus. Level 3
(L3) cache is specialized memory developed to improve the performance
of L1 and L2.
Activity A
1. Computer’s motherboard, processor, and CPU are the same or
different things?
………………………………………………………………………..
………………………………………………………………………..
………………………………………………………………………..
2. What’s the difference between cache and RAM?
………………………………………………………………………..
………………………………………………………………………..
………………………………………………………………………..

2.6 INPUT/ OUTPUT DEVICES

They are used as a medium of communication between the external
environment and the CPU. The input is provided to the computer through
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Information Technology the input devices and the output is given through the output devices. The
for Managers input and output devices are controlled by the CPU. A computer system
may also have devices under the control of CPU dedicated for controlling
the input output devices.
Input Devices
Table 2.2 highlights the categories into which the input devices fall. Voice
Recognition devices are used to recognize human speech. It converts human
voice signals received through microphone to digital signals using software
tools. Voice recognition systems are becoming popular.
Table 2.2: Categories of Input devices
Category Name of Device
Keyboard
Keying Device
Punched card reader
Mouse
Touch Screen
Pointing Devices
Joy Stick
Light Pen
Voice Recognizers
Bar Code Reader, QR Code Reader
Optical Character
Optical Mark Reader
Recognizer
Optical Character Reader / Optical Scanner
Cameras
Digitizers ( for maps, graphs etc)
Other Devices Smart Cards
Telephone and other handheld devices for
capturing data and information
Bar Code Reader scans the code (black and white bars), which specifies the
name of the product and its manufacturer. The computer then finds the price
of the product from the database. It is used for high- volume processing of
data where use of keyboard entry can be very time consuming, for example
they are used in supermarkets. QR Codes are used to specify details of data
and information contained in a document. It is used for establishing the
authenticity of data and information contained in it.
Digital cameras are used to capture pictures. The pictures are digitized
and stored in computers. The pictures can be reviewed, deleted, edited,
and saved for future use. Images can be transmitted from a PC to a printer
or to other cameras. They can be mailed to friends. Digitizers are devices
that convert drawings made on sensitized surface with the help of pen to
machine-readable input. These inputs are transferred to the computer. A
smart card is a card that is embedded with either a microprocessor and a
memory chip or only a memory chip with non-programmable logic. The
microprocessor card can add, delete, and otherwise manipulate information
on the card, while a memory-chip card (for example, pre-paid phone cards)
can only undertake a pre-defined operation.
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Output Devices Computer Systems and
Smart Devices
The output generated by a computer can be transmitted to the user via several
devices and media. These devices are called output devices. Following are
some important output devices:
1. Monitors: It is a video screen that displays both input and output data.
It comes in different sizes ranging from few inches to several feet. It
is interactive in nature, which is the main advantage associated with
this device. It consists of CRT (Cathode Ray tube) technology. It is
the electronic “gun” that shoots the beam of electrons and illuminates
the pixels on the screen.
2. Printers: There are two broad categories of printers i.e. Impact and
Non Impact Printers. Impact printer uses striking action to press a
carbon against paper to create a character. Dot matrix, Line, and Daisy
wheel are some important type of Impact printers. They are slow and
noisy. They don’t support graphics and are susceptible to mechanical
breakdowns.
Non Impact Printers use laser beams to write information on
photosensitive drums. The paper passes over the drum and picks
the image with toner. Laser Printer is the example of Non Impact
Printers. They have high speed and can produce print- quality text
and graphics. Ink–jet printers are Non Impact Printers, which shoot
tiny dots of ink on the paper. They are inexpensive and are used for
low volume graphical applications when different colors of ink are
required.
3. Audio Devices/Speakers/Headphones: The outgoing audio data
requires the sound amplifying devices, and a few such audio output
devices are Speakers & Headphones. These output devices are
connected to the main computing devices in order to get the output
audio data from the processing unit. An important hardware unit is
required or enabling a smooth function between the computer system
and the audio devices are the Sound card.
4. Projector: Projectors are another type of display devices, which are
used for displaying the outcomes from the computer system on to
a different exterior surface, by reproducing the same computer’s
contents for projection. It is a common understanding that the output
data can be displayed clean and clear if the display surface is a plain
hard surface white in color. This process is made possible using an
extra hardware card, known as the Video Card. A very common usage
of Projector devices are Movie Theater and Business Presentation.
5. Plotter: They use computer driven pens for creating black and white
or color graphic images likes charts, graphs etc. They are used in
engineering and architectural drawings.
6. Television: Televisions are the most famous and commonly used
output devices, which are used to display the video content and for
playing the audio files. It is a well-liked way of exhibiting the videos,
images, presentations, etc. for domestic as well as the technology-
related industries. It is generally called as TV or Telly that has had
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Information Technology evolved over the years from CRT screens to LCD displays to LED
for Managers screens to the latest Plasma displays.
7. Braille Reader: Braille Readers, as the name says, are used to
facilitating the computer functional handling for blind users. The
workings of this device involve the central processing system to
deliver the processed data in the Braille format, so as to make it
recognizable for the visionless disables. When the Braille Reader
receives the processed data, the data is converted to push the pins
against a flat surface. When the visually disabled use this device, they
can run their fingers through these Braille script and understand the
outcome easily. Similar to other output devices, this device comes in
a variety of sizes as well.
8. GPS: GPS stands for Global Positioning System device. This device
uses the satellite resources for capturing the geographical position
of the device. Hence, if the user holds this device in his hands the
geographical location of the user can be captured accurately. It
involves the calculation of exact latitude and longitude points for the
location required and share the outcomes to the user. In the evolving
technological world, all the portable devices are equipped with GPS
systems, as it helps in locating the device when lost or stolen. The
devices that come with inbuilt GPS units are mobile phones, wearable
digital tracking devices, laptops, tablets, cars, bicycles, watches, and
even shoes.
9. Video Card: Video Card is a hardware device that can be placed in the
dedicated sockets provides inside the motherboard of the computer’s
processing unit. It is typically used for improvising the appearance of
the digital content displayed in the other display based output devices.
In recent days, this has become an indispensable element to keep up
with the growing quality of content in the latest systems.

2.7 NETWORKING AND NETWORKING

DEVICES
A network is a group of computers, printers, and other devices that are
connected together with cables. Data travels over the cables, allowing
network users to exchange documents and data with each other. Many
users can use the same printer and share hardware and software that are
connected to the network. Each computer, printer, or other peripheral device
that is connected to the network is called a node. A network can have tens,
thousands, or even millions of nodes.
The number of possible ways to logically arrange the nodes, or computer
systems and devices on the networks are mainly of five types. They are
termed as network topologies, i.e. the logical model that describes the
network structure or configuration. These types are bus, ring, hierarchical,
star and hybrid.
The computers in the ring network are connected in ring or circle. There
is no central computer and messages are routed around the ring from one
device to another in one direction. In the bus network the devices are
connected on the single line. Each device is connected to the single bus
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and can directly communicate with all other devices on the network. A star Computer Systems and
network has a central computer. This central computer controls and directs Smart Devices
messages. If the central computer breaks down, entire system is broken
down. The hierarchical structure has tree like structure and does not have a
central computer. Messages pass through all the branches of the tree till they
reach the destination. This structure is easy to repair as any branch can be
isolated and repaired without affecting any other branch. Hybrid network is
the combination of two or more topologies.

Ring Structure
Hybrid Structure Star Structure

Bus Structure
Tree Structure
Figure 2.3: Types of Network Topologies

Network Devices
Network devices allow multiple computers to exchange data and information
through Internet or Intranet connection. Many people can use a single
printer, or share other devices and resources on the network. Every network
has a router which is a device that connects two or more networks and
determines the next point to which a ‘packet’ of data should be forwarded
towards its destination. A packet is the smallest unit of data that travels on
the network. Hub and Switch are the center points where several network
connections converge i.e. they are the points where data comes in from one
or more directions/locations and is forwarded to one or more directions/
locations. Sometimes the same device serves as both the switch and router.
NIC (Network Interface Card) is a card installed on a computer that connects
the computer to the network. It provides dedicated and full-time connection
to the computer.

2.8 PLUG AND PLAY DEVICES

Plug and Play (also called PnP) specification was developed by Microsoft
with cooperation from Intel and many other hardware manufacturers. The
goal of Plug and Play is to create a computer whose hardware and software
work together to automatically configure devices and assign resources, to
allow for hardware changes and additions without the need for large-scale
resource assignment tweaking. As the name suggests, the goal is to be able
to just plug in a new device and immediately be able to use it, without
complicated setup maneuvers.
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Information Technology The plug and play feature was introduced in Windows 2000. One can plug
for Managers in, for instance, an USB (Universal Serial Bus) device and it is detected and
accepted by the system so that the device can be used without rebooting the
system. Operating system has drivers for most of the devices. When a device,
for which operating system has the driver, is plugged in, the communication
between the driver and the device is established by the OS. These devices
are connected to the computer in several ways. Some devices, such as
network adapters and sound cards, are connected to expansion slots inside
the computer. Other devices, such as printers and scanners, are connected
to ports outside the computer. Some devices, known as PC Cards, connect
only to PC Card slots on a portable computer. The operation system must
have device drivers for all plug and play devices.
USB is the industry standard for attaching peripheral devices to the
computer. This technology is designed for use with almost all devices,
including printers, digital cameras, game pads, joysticks, keyboards and
mouse, TVs, storage devices. USB hardware is identical across platforms.
It replaces all the different kinds of serial and parallel port connectors
with one standardized plug and port combination. The devices can plug in
without opening the PC.
Activity B
What were the main reasons for the change from the serial, printer, game,
and ps/2 ports to the USB port?
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………

2.9 SMART DEVICES

Smart devices are interactive electronic gadgets that understand simple
commands sent by users and help in daily activities. Some of the most
commonly used smart devices are smartphones, tablets, phablets,
smartwatches, smart glasses and other handheld personal electronics items.
With the digitalization in practice almost in every field such devices are
very commonly seen everywhere. A smart device is able to connect, share
and interact with its user and other smart devices. Although usually small in
size, smart devices typically have the computing power of a few gigabytes.
Such devices are very common these days in information gathering and
further dissemination. They are all of the everyday objects made intelligent
with advance computing including artificial intelligent and machine
learning. They are networked to form the internet of things (IoT). These
small devices are powerful enough to process data. They range from sensors
to refrigerators and wearable to container transportation, capable of running
autonomous workloads.

2.10 COMMUNICATION TECHNOLOGY

Communications is the transmission of a signal by a way of particular
medium from a sender to a receiver. For example in human speech, the
sender transmits a signal through the transmission medium air.
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 Signal Computer Systems and
Smart Devices
sign

Sender Receiver

Transmission
Medium

For the effective communication both the sender and the receiver should
understand the signals and have common interpretation for them. When
communication has to be established a medium is required for transmission.
This pathway/medium is called as communication media. It includes twisted
pair, coaxial cable, fiber optic cable, microwave transmission, and satellite
transmission. With fiber-at-home communication media you get high speed
internet connectivity at your home with applications like internet TV (iTV)
giving the facility of watching TV channels, browsing web sites and can
play and view audio/video programs of your interest.
There are two modes of communication – Synchronous and Asynchronous.
In Synchronous transmission, data bits are sent over a communication link
and the data transfer is controlled by a timing signal initiated by the sending
device. Each data block is preceded by unique characters called sync
bits. The receiving device synchronizes itself with a stream of these bits.
Synchronous transmission is generally used for transmitting large volume
of data at high speed. For Asynchronous transmission, one character is
transmitted or received at a time. Each character is preceded by start bit and
ended with end bit, so that the receiving device knows where the character
begins and ends. It is inefficient due to the overhead of transmitting start
and stop bits. It is generally used for low speed data transmission.
Data transmission occurs in one of the following three directions: Simplex,
half duplex, or full duplex. In simplex data transmission, the data transmission
takes place in only one direction. Public announcement systems such as
radio and television use simplex mode of data transmission. It is simple and
relatively inexpensive. In half- duplex transmission mode, the transmission
takes place in both directions but only in one direction at a time. Full duplex
mode of transmission allows transmission in both directions simultaneously.
For example, on telephone both parties can communicate simultaneously.
The cost of full duplex transmission is high as compared to both simplex
and half duplex.

2.11 TYPES OF COMPUTERS

Mainframes: Mainframes are not as powerful and not as expensive as super
computers. A large organization generally uses a mainframe as a contact
database and file server.
Minicomputers: There are also called midrange computers. There are
less powerful than mainframes. Minicomputers are used for specific tasks
such as scientific research and engineering applications. Some times, large
organizations install many minicomputers instead of one mainframe. The
application, and data are distributed ones minicomputer to achieve better
reliability. Small organizations use a minicomputer as a server.
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Information Technology Workstations: A workstation is usually based RISC architecture, provides
for Managers high solution graphic displays and high-speed calculations. Scientific and
business community uses these machines.
Microcomputer: Microcomputers, also called personal computers, are
general-purpose computers. A PC that sits on a desk is called desktop
personal computer in contrast to a laptop computer, which is portable.
Network Computer: A network computer (NC) is a desktop terminal that
is connected to a central computer. A NC has essentially no storage, no
CPU, and no secondary storage. It has a keyboard and a video display. It
uses processing power and storage of its central processor.

2.12 SUMMARY
In this unit, we have discussed an introduction to computer systems. The
components of computer, which we explained in detail include: CPU, ALU,
storage, and I/O devices. The CPU works as the brain of the system, while
RAM is the working memory of the system. Today’s computers come with
possibilities to use many plug and play devices, and they are also network
compatible. There are smart devices available today for information
gathering, processing and further disseminating. We have also discussed
the concepts related to networking in this unit, where we have described
the various media used such as co-axial cable, satellite, fiber optics, and
microwave communication. At the end, we have given a brief overview of
different types of computers though generations.

2.13 UNIT END EXERCISES

1. What are the components of a computer system?
2. What are the components of a CPU?
3. What factors affects the speed of a computer?
4. Write a detailed note on primary memory.
5. Write a detailed note on secondary memory.
6. Write a detailed note on Input-Output devices.
7. What are plug-and-play devices?
8. What are various types of computer?

2.14 REFERENCES AND SUGGESTED

FURTHER READINGS
Fitzherald, J.and Dennnis A, Business Data Communications and
Networking; John Wiley & Cons. Inc.
Laudon C K & Laudon J P, Management Information Systems, Pearson
education, Asia.
Turban, T., Ephraim, M. and Wetherbe J., Information Technology for
Management, John Wiley and Sons, Inc.
www.arm.com, site accessed on November 15, 2021.
www.diskpart.com, site accessed on November 15, 2021.
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