ch01_Intro to Computer & Programming.pdf

Starting out with Programming Logic and
Design
Sixth Edition
Chapter 1
Introduction to Computers
and Programming
Copyright © 2022, 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved

1.1 Introduction (1 of 4)
• People use computers at…
– School for writing papers, research, email, online
classes, etc.
– Work for analyzing data, make presentations,
business transactions, communicating, control
machines, etc.
– Home for paying bills, shopping online,
communicating, playing computer games, etc.
What are some of the ways you use computers?

• Devices that are computers…
– SmartPhones
– MP3 Players
– Tablets
– Car navigation system (GPS)
Can you think of some other devices that are
computers?

• Computers are designed to do any job that their
programs tell them to do.
• A program is a set of instructions that a computer follows
to perform a task.
For example: Microsoft Word and PowerPoint
• Programs are commonly referred to as software.
What software have you used?

• Programmers or Software Developers are the
individuals that create computer software.
• They have the training and skill to design, create, and
test computer programs.
What are some of the fields in which computer
programs are used?

1.2 Hardware and Software (1 of 18)
Concept:
The physical devices that a computer is made of are
referred to as the computer’s hardware. The programs that
run on a computer are referred to as software.

Hardware
• The physical devices that a computer is made of are
referred to as the computer’s hardware.
• A computer is a system of devices that work together.

Hardware
A Computer System
consists of:
• Central Processing Unit
(CPU)
• Main memory
• Secondary storage
• Input devices
• Output devices
Figure 1-2 Typical components
of a computer system

Hardware
Central Processing Unit (CPU)
• The CPU is the part of a computer that runs the
programs.
• Often referred to as the processor.
• Without a CPU, a computer cannot run software.
Running or executing a program is the term used when
the computer performs the tasks that the program tells it to
do.

Hardware
ENIAC
• World’s first programmable
computer
• Built in 1945
• Designed to calculate
artillery ballistic tables for
the U.S. Army
• CPU was 8 feet tall, 100
feet long, and weighed 30
tons
Figure 1-3 The ENIAC
computer (courtesy of U.S.
Army Historic Computer
Images)

Microprocessor
• Much smaller
• Much more powerful
Figure 1-4 A lab technician holds a
modern microprocessor (photo
courtesy of Intel Corporation)

Main Memory
• Considered the computer’s work area
• Computer stores the program that is running as well as the
data
• Commonly known as the random-access memory (RAM)
• Data is quickly accessed
• RAM is a volatile type of memory
• Used for temporary storage
• RAM is erased when computer is turned off

• Read-Only Memory (ROM)
– A computer can read the contents of ROM, but it
cannot change its contents, or store additional data
there.
– ROM is nonvolatile. It does not lose its contents,
even when the computer’s power is turned off.
– ROM is typically used to store programs that are
important for the system’s operation. For example, the
computer’s startup program, which is executed each
time the computer is started.

Secondary Storage Devices
• Type of memory that can hold data for long periods of time.
• Programs and important data are stored in secondary storage
• Disk drive is a common type of secondary storage
– Data is stored by magnetically encoding it onto a
circular disk
– Most computers have an internal disk drive
– Some have external disk drives; they are used to create
backup copies

• Solid-State drives are becoming increasingly popular
– Does not contain a disk. Instead, it stores data in
solid-state memory
– No moving parts
– Operates faster than a traditional disk drive

• USB drives are small devices that plug into the
computer’s universal serial bus (USB) port
– It does not contain a disk
– The data is stored on flash memory
– Also known as memory sticks and flash drives
– Inexpensive, reliable, and small

• Optical devices (CD or DVD)
– Data is encoded as a series of pits on the disc’s
surface
– Uses laser to encode the data
– Holds large amounts of data
– Good medium for creating backups

• Cloud Storage
– When you store data in the cloud, you are storing it
on a remote server via the internet, or via a
company’s private network.
– You can access it from many different devices, and
from any location where you have a network
connection.
– Can also be used to backup important data that is
stored on a computer’s disk.

Input Devices
• Any data the computer collects from people and from other devices is called
input.
• The hardware component that collects the data is called an input device.
• Common input devices are:
– Keyboard
– Mouse
– Touch screen
– Scanner
– Microphone
– Digital camera
Can you think of any other input devices?

Ouput Devices
• Any data the computer produces for people or for other
devices is called output.
• The hardware component that formats and presents the
data is called an output device.
• Common output devices are:
– monitor
– printer
Can you think of any other output devices?

Software
• Everything a computer does is controlled by software.
• Two categories of software:
– System software
– Application software

System Software
• Programs that control and manage the basic operations of a
computer are referred to as system software.
• Includes the following types:
– Operating System controls the internal operations of the
computer’s hardware and manages all of the devices
connected to the computer.
– Utility Programs perform a specialized task that
enhances the computer’s operation or safeguards data.
– Software Developments Tools are programs that are
used to create, modify, and test software.

Application Software
• Programs that people normally spend most of their time
running on their computers performing everyday tasks are
referred to as application software.
• For example:
– Word processing
– Spreadsheet
– Database
– Presentation
Can you think of any other application software?

1.3 How Computers Store Data (1 of 9)
Concept:
All data that is stored in a computer is converted to
sequences of 0s and 1s.

• A computer’s memory is divided into tiny storage locations known as bytes
• One byte represents one number
• A byte is divided into eight smaller storage locations known as bits (binary
digits)
• Bits are tiny electrical components that can hold either a positive or a
negative charge.
• A positive charge is similar to a switch in the on position
• A negative charge is similar to a switch in the off position
Figure 1-6 Think of a byte as eight
switches

Storing Numbers
• The positive charge or the on position is represented by the digit 1
• The negative charge or the off position is represented by the digit 0
• This corresponds to the binary numbering system where all numeric
values are written as a sequence of 0s and 1s
• Each digit in a binary number has a value assigned to it
Figure 1-8 The values of binary digits as
powers of 2

For example:
Figure 1-10 Determining the
value of 10011101
Figure 1-11 The bit pattern for
157

• The largest value that can be stored in a byte with eight
bits is 255
• Two bytes are used for larger numbers; maximum value
is 65535
Figure 1-12 Two bytes used for a large number

Storing Characters
• Characters are stored in the computer’s memory as
binary number
• ASCII (American Standard Code for Information
Interchange) is a coding scheme
Figure 1-13 The letter A is stored in memory as the number 65

• ASCII is a set of 128 numeric codes
• ASCII is limited
• Unicode is an extensive encoding scheme
– It is compatible with ASCII
– It represents characters for many languages in the
world

Advanced Number Storage
• Binary numbering system can be used to represent only
integer numbers
• Negative numbers are encoded using two’s
complement
• Real numbers are encoded using floating-point
notation

Other Types of Data
• Digital data is data that is stored in binary
• A digital device is any device that works with binary data
• Digital images are composed of tiny dots of color known
as pixels (picture elements)
• Digital sound is broken into small pieces known as
samples

1.4 How a Program Works (1 of 12)
Concept:
A computer’s CPU can only understand instructions that
are written in machine language. Because people find it
very difficult to write entire programs in machine language,
other programming languages have been invented.

• CPU is the most important component in a computer
• CPU is not a brain
• CPU is not smart
• CPU is an electronic device that is designed to do
specific things.

CPU is designed to perform the following operations:
• Read a piece of data from main memory
• Adding two numbers
• Subtracting one number from another number
• Multiplying two numbers
• Dividing one number by another number
• Moving a piece of data from one memory location to another
• Determining whether one value is equal to another value

• CPU only understands instructions written in machine
language
• Machine language instructions are written in 1s and 0s
• The entire set of instructions that a CPU can execute is
known as the CPU’s instruction set
• Each brand of microprocessors (Intel, AMD, and
Motorola) has a unique instruction set

• Fetch-decode-execute
cycle is the term used
when the CPU executes
the instructions in a
program.
• The cycle consist of
three steps:
– Fetch
– Decode
– Execute
Figure 1-16 The fetch-decode-
execute cycle

From Machine Language to Assembly Language
• Computers only understand machine language
• Machine language is difficult to write
• Assembly language uses short words that are known as
mnemonics
• Assembler is used to translate an assembly language
program to machine language

Figure 1-17 An assembler translates an assembly language program
to a machine language program

High-Level Languages
• Assembly language is referred to as a low-level
language High-level languages allow you to create
powerful and complex programs without knowing how the
CPU works, using words that are easy to understand.
For example:
Java, C++, Python, Visual Basic, C# , Ada, Fortran
Do you know of any other high-level computer
programming languages?

Key Words, Operators, and Syntax: an Overview
• Key words or reserved words have specific meaning
and purpose in the programming language
• Operators perform various operations on data
• Syntax is a set of rules that must be strictly followed
when writing a program
• Statements are individual instructions written in a
programming language

Compilers and Interpreters
• The statements written in a high-level language are
called source code or simply code
• Source code is translated to machine language using a
compiler or an interpreter
• Syntax error is a mistake such as a:
– Misspelled word
– Missing punctuation character
– Incorrect use of an operator

• Compiler is a program that translates a high-level
language program into a separate machine language
program
Figure 1-18 Compiling a high-level program and executing it

• An interpreter is a program that both translates and
executes the instructions in a high-level language
program
Figure 1-19 Executing a high-level program with an interpreter

1.5 Types of Software
Programs generally fit into one of two categories
• System software
– The set of programs that control or enhance the
operation of a computer such as an Operating
System, Utility Programs, or Software Development
Tools.
• Application software
– Programs that make a computer useful for every day
tasks such as Microsoft Word, email programs, and
Web browsers.

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