Download Program, Hardware, CPU - Introduction to Computer Science | CS 1400 and more Study notes Computer Science in PDF only on Docsity!
cs
Introduction to
Computer Science
Chapter 1
Computers and
Programming
Why Program?
The ultimate multi-purpose tool
Hardware
Hardware – the stuff you can touch
“The easiest way to tell the difference between
hardware and software is to kick it. If it hurts
your toe, it’s hardware.”
Anonymous
The CPU
CPU – Central Processing Unit
The "brains" of the computer
Responsible for controlling its inner workings
CPU
made of circuitry – electronic components wired together to
control the flow of electrical signals
the circuitry is embedded in a small silicon chip, 1-2 inches
square
despite its small size, the CPU is the most complex part of a
computer
(CPU circuitry can have 100's of millions of individual components)
CPU
Control Unit
Arithmetic Logic Unit (ALU)
Registers
CPU Organization
Main Memory
Addresses – Each byte in memory is identified
by a unique number known as an address.
The number 149 is stored in the byte with the
address 16, and the number 72 is stored at
address 23.
60 Bytes
2975482 W e l c
o m e t o C
S \0 $ % 0
G O O D B Y E!
Secondary Storage
Non-volatile
Comes in a variety of media:
magnetic: floppy disk, hard drive
optical: CD-ROM, DVD
Flash drives, connected to the USB port
Slower
Less expensive
Input Devices
Devices that send information to the
computer from the outside world
Keyboard
Mouse
Scanner
Digital camera
Microphone
Output Devices
Output is information sent from a computer
program to the outside world
Monitor
Printer
Speakers
Input/output devices
??
?
?
Input/Output Devices
Translate between computer representation
and real world representation
Software
The instructions that make it all work
Software
software refers to the programs that execute
on the hardware
a software program is a sequence of
instructions for the computer (more
specifically, for the CPU) to carry out in order
to complete some task
The OS
manages the CPU time
multitasking
organizes the I/O devices
manages memory
files
directory
Programs and
Programming Languages
Types of languages:
Low-level: used for
communication with computer
hardware directly.
High-level: closer to human
language
Machine Language
Assembly Language
Hardware
Machine Language
High-Level
Programming Language
Algorithm
From human to computer
We can use the computer to do much of the
translation
We think in algorithms
We translate to a high-level programming
language – Source Code
Software can translate from high-level
programming language to machine language
Algorithm – Simple Definition
a set of step-by-step instructions to
accomplish a task
Algorithm Algorithm
1. Print "How many hours did you work?"
2. Get hoursWorked
3. Print "How much do you get paid per hour?"
4. Get payRate
5. compute wages: wages = hoursWorked*payRate
6. Print "You have earned $", wages
Some Well-Known Programming
Languages
BASIC
FORTRAN
COBOL
C
C++
C#
Java
JavaScript
Python
Ruby
Visual Basic
Preprocessor
Source Code
Modified
Source Code
Object Code
Executable Code
Compiler
Linker
Integrated Development
Environments (IDEs)
An integrated development environment, or
IDE, combine all the tools needed to write,
compile, and debug a program into a single
software application.
plain text editor
compiler
debugger
syntax highlighting
etc.
Integrated Development
Environments (IDEs)
Key Words
// This program calculates the user's pay. #include using namespace std;
int main() { double hoursWorked, payRate, grossPay;
// Get the number of hours worked. cout << "How many hours did you work? "; cin >> hoursWorked;
// Get the hourly pay rate. cout << "How much do you get paid per hour? "; cin >> payRate;
// Calculate the pay. grossPay = hoursWorked * payRate;
// Display the pay. cout << "You have earned $" << grossPay << endl; return 0; }
Programmer-Defined Identifiers
Names made up by the programmer
Not part of the C++ language
Used to represent various things: variables
(memory locations), functions, etc.
In Program 1-1: hoursWorked, payRate,
and grossPay.
Programmer-Defined Identifiers
// This program calculates the user's pay. #include using namespace std;
int main() { double hoursWorked, payRate, grossPay;
// Get the number of hours worked. cout << "How many hours did you work? "; cin >> hoursWorked;
// Get the hourly pay rate. cout << "How much do you get paid per hour? "; cin >> payRate;
// Calculate the pay. grossPay = hoursWorked * payRate;
// Display the pay. cout << "You have earned $" << grossPay << endl; return 0; }
Operators
Used to perform operations on data
Many types of operators:
Arithmetic - ex: +,-,*,/
Assignment – ex: =
Some operators in Program1-1:
Operators
// This program calculates the user's pay. #include using namespace std;
int main() { double hoursWorked, payRate, grossPay;
// Get the number of hours worked. cout << "How many hours did you work? "; cin >> hoursWorked;
// Get the hourly pay rate. cout << "How much do you get paid per hour? "; cin >> payRate;
// Calculate the pay. grossPay = hoursWorked * payRate;
// Display the pay. cout << "You have earned $" << grossPay << endl; return 0; }
Punctuation
Characters that mark the end of a statement,
or that separate items in a list
In Program 1-1: , and ;
Punctuation
// This program calculates the user's pay. #include using namespace std;
int main() { double hoursWorked, payRate, grossPay;
// Get the number of hours worked. cout << "How many hours did you work? "; cin >> hoursWorked;
// Get the hourly pay rate. cout << "How much do you get paid per hour? "; cin >> payRate;
// Calculate the pay. grossPay = hoursWorked * payRate;
// Display the pay. cout << "You have earned $" << grossPay << endl; return 0; }
IDE text highlighting
// This program calculates the user's pay. #include using namespace std;
int main() { double hoursWorked, payRate, grossPay;
// Get the number of hours worked. cout << "How many hours did you work? "; cin >> hoursWorked;
// Get the hourly pay rate. cout << "How much do you get paid per hour? "; cin >> payRate;
// Calculate the pay. grossPay = hoursWorked * payRate;
// Display the pay. cout << "You have earned $" << grossPay << endl; return 0; }
Syntax
The rules of grammar that must be followed
when writing a program
Controls the use of key words, operators,
programmer-defined symbols, and
punctuation
Variables
A variable is a named storage location in the
computer’s memory for holding a piece of
data.
length width
Variables
In Program 1-1 we used three variables:
The hoursWorked variable was used to hold the
hours worked
The payRate variable was used to hold the pay
rate
The grossPay variable was used to hold the
gross pay
Variable Definitions
To create a variable in a program you must write
a variable definition (also called a variable
declaration)
Here is the statement from Program 1-1 that
defines the variables:
double hoursWorked, payRate, grossPay;
