Transcript Introduction to Programming - Cleveland State University

Software Tools
Instructor: Sanchita Mal-Sarkar
Course: IST 203
Computer
• An electronic machine that accepts input,
processes data, stores data, and produces
output.
• Data can be numbers, text, images,
graphics, and sound, etc.
• Computer program is a set of instructions.
Without it computer is useless.
• Programming languages allow us to write
these instructions (e.g. C, C++, Java, etc).
Types of Computers
• Computers are classified by their size, speed, and cost.
• Microcomputers
- desktop or tower.
- A notebook computer
- Personal digital assistant (PDA)
• Minicomputers
• Mainframes
• supercomputers
Microcomputers
• Microcomputers => Also called personal
computers.
• These computers are typically used by a single
user, usually at home or at office. They can be of
different shapes and sizes.
• A notebook computer (laptop) => small and light.
Portable (standard desktop does not have). It can
run on power from an electrical outlet or
batteries. Expensive.
• Personal digital assistant (PDA) =>more portable
than notebook computer. It has limited capability.
Also known as palmtop.
Minicomputers
• Minicomputers => Somewhat larger than
microcomputers. The computing capability of a
minicomputer may be more than a microcomputer.
• Usually a company purchases a minicomputer
when it needs to share large amount of data among
many users.
• Each user inputs processing requests and views
output through a terminal.
• The terminal has a keyboard for input and a
display screen for output, but it does not process
the user’s data. The processing requests will be
transmitted from the terminal to the minicomputer.
Mainframes
• Larger and powerful than minicomputers.
• The mainframe computers can handle many more users
than a minicomputer.
• These are used to provide centralized storage,
processing, and management for large amounts of data.
• Insurance companies use mainframes to process
information about millions of policyholders.
Supercomputers
• The largest and fastest computers.
• First developed for high volume computing
tasks, such as weather prediction.
• These are also used in a large corporation
because they can process tremendous volume of
data in a relatively shorter time compared to
other computers (microcomputers,
minicomputers, and mainframes).
Computer system
• A computer system consists of a computer, peripheral
devices, and software.
• The computer itself can take care of the processing
function, but it needs additional components, called
peripherals, to accomplish its input, output and storage
functions.
• Example of an internal peripheral device is hard disk
drive.
Computer Hardware
• Hardware is the physical component of a
computer.
• Hardware is the equipment used to
perform the necessary computations.
• Examples:
Main memory (RAM, ROM), secondary
memory (hard disk drive, floppy disk drive),
CPU, input devices (keyboard and mouse),
and output devices (monitor and printer).
Hardware Components of a Computer System
Central Processing Unit (CPU)
• Arithmetic-Logic Unit
• Control Unit
Input Devices
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Secondary Storage
• Magnetic disk
• Optical disk
• Magnetic tape
Keyboard
Computer mouse
Touch screen
Source data automation
Output Devices
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Printers
Video display terminals
Plotters
Audio output
Communications
Devices
Primary Storage
Central Processing Unit (CPU)
• Coordinating all computer operations.
• Performs arithmetic and logical operations on data.
• To process a program stored in main memory,
- CPU retrieves each instruction in sequence.
-
Interprets the instruction to determine what should be
done.
Retrieves any data needed to carry out that instruction
Then CPU performs the actual manipulation.
• CPU’s current instruction and data values are stored
temporarily inside the CPU in special high-speed
memory locations called registers.
Central Processing Unit (CPU)
• The CPU consists of a control unit and an arithmeticlogic unit.
• Three kind of buses link the CPU, primary storage,
and other devices in the computer systems.
• The data bus moves data to and from primary storage.
• The address bus transmits signals for locating a given
address in primary storage.
• The control bus transmits signals specifying whether
to read or write data to or from a given primary storage
address, input device, or output device.
Data Bus, Address Bus, and Control Bus
Central Processing Unit (CPU)
Primary Storage
1
Arithmetic-Logic Unit
24 + 12 = 36
12 < 24
8
#
T
U
Control Unit
Data Bus
Address Bus
Control Bus
Input Devices
Output Devices
Secondary
Storage
Main Memory
• Computer memory is a set of storage
locations on the main circuit board
(motherboard).
• Four types of memory:
– RAM, Virtual memory, ROM, and CMOS
(complementary metal oxide semiconductor
memory)
Random access memory
• Consists of electronic circuits on the
motherboard (main circuit board).
• Temporarily hold programs and data while
the computer is on.
• Each circuit has address that is used by the
microprocessor to transmit and store data.
• RAM is constantly changing (volatile).
• E.g. When we write a paper, the word
processing program will be temporarily
copied into RAM so that microprocessor
can quickly access the required instructions.
Virtual Memory
• Today’s microcomputer software uses space
on computer’s storage devices to simulate
RAM if more needed.
• This extra memory is called virtual
memory.
• How it works?
• Suppose my computer is running a word
processing program that takes up most of
the memory in RAM, but I want to run a
spreadsheet program at the same time.
Virtual Memory (Cont.)
• The OS moves the infrequently used
segment of the word processing program
into virtual memory on disk.
• The spreadsheet program now can be
loaded into RAM.
• If that segment is later needed, it is copied
from virtual memory back to RAM.
• Disadvantage:It is much slower than RAM.
Read-only memory(ROM)
• Another set of electronic circuits on the
motherboard inside the computer.
• We cannot increase ROM capacity.
• Manufacturer permanently installs ROM.
• When computer is on, the sets of
instructions in ROM checks
• all the computer system’s components to
make sure they are working and
• activates the essential software that controls
the processing function.
Complementary metal oxide
semiconductor(CMOS)
• A chip installed on the motherboard.
• Activated during the boot process.
• Contains information about where the
essential software is stored.
• A small rechargeable battery powers CMOS.
• It changes every time we add or remove
hardware to the computer system.
• CMOS is referred as semipermanent memory.
Secondary Storage Devices
• RAM retains data only when the power is
on, so computer must have a more
permanent storage option.
• The most common magnetic storage devices
are hard disk drive, floppy disk drives, and
tape drives.
Hard disk drive
• Provides a storage area to be shared by all
users of the computer.
• Generally, the programs that are needed to
operate the computer system are stored
here.
• Advantages over floppy disk: speed and
capacity.
Hard Disk Drive
Internal Components
Floppy disk drive
• Most common magnetic storage device.
• Users can have any number of floppy disks
that can be inserted into computer’s floppy
disk drive.
• High density disk- capacity to store 1.44
MB.
• Low-density disk - capacity to store 720
KB.
Tape drive
• Another magnetic storage device.
• Provides inexpensive archival storage for
large quantities of data.
• Too slow to be used for day-to-day tasks.
• Used to make backup copies of data stored
on hard disks.
• If a hard disk fails, data from the backup
tape can be reloaded on a new hard disk.
Compact Disk Read Only Memory (CD-ROM)
• Optical storage device.
• Uses laser technology to read and write data on
compact discs (CDs).
• High capacity and portability. Can store up to 680
MB, equivalent to more than 450 floppy disks.
• Relatively slow access. Mainly used for software
distribution and storing large data files such as
graphics, animation, and video.
Input Devices
• Input device - keyboard, mouse.
• Input devices translate data & programs that
humans can understand into a form that computer
can process.
• When we press a letter or digit key on a key board,
that character is sent to main memory and
displayed on the monitor.
• Keyboard consists of three major parts: main
keyboard, keypads, and function keys.
• A mouse is a hand-held device used to select an
operation.
Output Devices
• Shows the result of processing data.
• Output devices - monitor and printer.
• Output devices translate the processed information
from the computer into a form that humans can
understand
• Monitor is the TV-like device that displays the
output from a computer.
• Printer produces a hard copy of the text or
graphics processed by the computer.
Computer Software
• Software consists of the computer
programs that allow us to solve problems by
providing sets of instructions.
• Examples:
DOS, Windows, Mac. Office family, Lotus,
Netscape, Internet Explorer, Virus scans,
tax programs, computer games, GUI Graphical User Interface.
Computer Software
• Computer hardware is useless without software.
• Software is the set of instructions and associated
data that direct the computer to do a task.
• Software can be divided into two categories:
• System software and application software.
• System software helps the computer to carry out
its basic operating tasks.
• Application software helps the user carry out a
variety of tasks.
System Software
• Manages the fundamental operations of the
computer, such as
– loading programs and data into memory,
executing programs, saving data to disks,
displaying information on the monitor, and
transmitting data through a port to a peripheral
device.
• Four types of system software: operating
systems, utilities, device drivers, and
programming languages.
Operating System
• Collection of computer programs that control the
interaction of the user and the computer
hardware.
• Responsible for directing all computer operations
and managing all computer resources.
• Controls basic input and output, allocates system
resources, manages storage space, maintains
security, and detects equipment failure.
• A part of the operating system code is stored in a
ROM and the rest of it resides on a disk.
• Loading the operating system into memory is
called booting the computer.
Responsibilities of an Operating System
• Communicate with user, receive and execute commands,
show error messages.
• Manage allocation of memory, processor time and other
resources.
• Collect input from keyboard, mouse, and provide data to
running programs.
• Convey program output to screen, printer, or other
output device.
• Access data from secondary storage.
• Write data to secondary storage.
• Maintains security (checks user-name , password, virus
infection)
Virus
• Virus => unscrupulous programmers deliberately
construct harmful programs (called viruses) that
instruct your program to perform destructive activities,
such as erasing a disk drive.
• Virus protection software => Computer users can
protect their computers by using virus protection
software.
• How it protects? Virus protection software searches
executable files for the sequences of characters that
may cause harm and disinfects the files by erasing or
disabling those commands.
Utilities
• Another category of system software.
• Augments the OS by taking over some of its
responsibility for allocating hardware
resources.
• Many utilities come with OS.
• Some independent software developers
offer utilities for sale separately.
• E.g. Norton Utilities by Symantec.
Device driver
• A computer program that can establish
communication because it contains
information about the characteristics of your
computer and of the device.
• Each peripheral device requires a device
driver.
• Helps the computer communicate with that
particular device.
• When we add a device to an existing
computer, part of its installation includes
adding its device driver to the configuration.
Computer programming
languages
• Another type of system software.
• Programmer uses to write computer
instructions.
• The instructions are converted into
electrical signals that computer can
manipulate and process.
• E.g. Basic, Visual Basic, C, C++, Cobol,
etc.
Application software
• Developed for a specific task , such as word
processing( MS Word/ WordPerfect),
accounting (Lotus 1-2-3/ Excel), or
database management (Access/ dBASE).
• We also use graphics and presentation
software.
• Most applications are purchased on diskette
or CD-ROM.
• They are installed by copying the programs
from the diskettes/CD-ROM to the hard
disk.
Word processing software
• Allows the user to store and modify text data
electronically as computer files.
• The software has formatting options to make
changes in line spacing, margins, character size,
and column width.
• It can also check spelling, grammar, and
punctuation.
• Popular word processing packages: MS Word,
WordPerfect.
Spreadsheet Software
• Spreadsheet software can be used to analyze and
summarize numerical data.
• Spreadsheet software creates a worksheet, composed of a
grid of columns and rows.
• You can write any character in each column.
• You can write any number in each row.
• The intersection of a column and row is called a cell. Each
cell has a unique address (cell reference).
• Using spreadsheet you can create graph (summary of data)
• Spreadsheet software provides you with excellent
printouts of the raw data or graphs created from the data.
Database Management Software
• Most popular types of application software. It is used to
organize and manage data
• A database is a collection of information stored in one or
more computers.
• A structured database is organized in a uniform format of
records and fields.
• A structured database contains data that describes a
collection of similar entities. For examples,
Name:
Student#
Student
# of courses taken in Fall 2004
GPA
Graphics & Presentation Software
• Graphics and presentation software allow us to create
illustrations, diagrams, graphs, and charts that you also
can print and transmit to remote computers.
• Most application software allows you to include
graphics created by graphics software (Microsoft Paint
or Adobe PhotoShop).
• You can also use clip art (a collection of drawings)
comes with software packages.
• MS PowerPoint is a popular presentation software. You
can create colorful presentations and transparencies.
Data Communications
• The transmission of text, numeric, voice, or video data
from one machine to another is called data
communications.
• For example, Send an electronic mail to your friends
around the globe.
• The four essential components of data communications
are a sender, a receiver, a channel, and a protocol.
Sender => The computer that originates the message is
called the sender.
Receiver => The computer at the message’s destination
is called the receiver.
Data Communications
Channel => The message needs some kind of medium
to be transmitted. This medium is called channel. For
example, telephone or coaxial cable, microwave signal,
or optical fibers
Protocol => The rules that establish an orderly transfer
of data between the sender and the receiver are called
protocols.
• Computer software and hardware establish these
protocols at the beginning of the transmission, and both
computers have to follow the protocols to ensure
accurate transfer of data.
Networks
• One of the most important types of data communications in
the business world is a network connection.
• A network connects one computer to another computers and
peripheral devices to share data and resources.
• There is a number of network configurations.
• local area network (LAN) => computers and peripheral
devices are located relatively close to each other, generally
in the same building.
• Client/server networks =>Some networks have file servers
(one or more computers) that act as the central storage
location for programs and that provide mass storage for
most of the data used on the network. A network with a file
server is called a client/server networks.
Networks
• Peer-to-peer networks => When a network does not
have a file server, all the computers essentially are
equal, and programs and data are distributed among
them. This is called a peer-to-peer network.
• Each computer that is part of the network must have a
network interface card installed. This device creates a
communication channel between the computer and the
network.
• Network software is also essential to establish the
communications protocols.
• Standalone computer => A microcomputer that is not
connected to a network is called a standalone computer.
Telecommunications
• Allows us to send and receive data over telephone
lines.
• A modem connects a computer to a telephone
jack.
• At the sending site, modem converts the digital
signal from a computer into analog (continuous
wave) signals (sound waves) that can traverse
ordinary phone lines (modulation).
• At the receiving site, a second modem converts
the analog signals back into digital signals
(demodulation).
Telecommunications
Internet
• The internet was originally developed for the government
to connect the researchers around the world to share data.
• Today, the internet is the largest network in the world that
connects millions of people in almost 200 countries.
• The use of internet:
electronic mail => This is the capability to send a message
from one user’s computer to another user’s computer
where it is stored until the receiver opens it. Message
passes through electronic links called gateways.
World Wide Web (Web) => Web is a huge database of
information that is stored on the network servers in places
that allow public access. The information is stored as text
files called web pages.
Internet
• Hyperlinks => a place on a computer screen that is
programmed to connect to a particular file on the same
network server, or on a network server on the other side
of the globe.
• Web browser => communication software that help us
navigate the WWW is called web browsing software or
web browser.