Itc lec 3 Ip cycle , system unit, interface

Introduction to
Computer Applications
Lecture # 3

Objective of Lecture
 Information processing life cycle
 input
 Output
 Processing
 Storage
 Components of System Unit
 Interface (user communication with computer)

What is the Information Processing Cycle?
 These are the steps that are taken to convert
raw facts, which is data, into information. It
starts with data collection.
 The 4 basic operations of the information
processing cycle are input, processing, output,
storage and/or distribution.
 A computer is the machine that performs that
cycle.

Component of system unit
The system unit is the main unit of a computer system. It
allows various parts of the computer system to work
together. A system unit consists of
 The Central Processing Unit(CPU)
 Semiconductor memory
 Magnetic memory and Disk drives
 Adapters and connectors

Contd..
 The main body of the computer consisting of plastic or
metal enclosure, the motherboard, (typically) internal
disk drives, a power supply(buses), cooling fans and
whatever circuit board plugged into the motherboard
such as video card, Sound card, Modem card.
 The system unit is occasionally referred to as the CPU,
though this really means central processing unit.

8
Power
supply
CD-ROM
drive
Floppy
disk drive
Hard disk
drive
Wires and
ribbon cables
Sound/network
cards
Inside a System unit
Mother
board

The Motherboard
 The most important part of a PC is the
motherboard. It holds:
 the processor chip
 memory chips
 chips that handle input/output (I/O)
 the expansion slots for connecting peripherals
 Some chips are soldered onto the
motherboard(permanent), and some are removable
(so they can be upgraded).

A Chip
 A chip (microchip) is an integrated circuit - a thin
slice of silicon crystal packed with microscopic
circuit elements
 e.g. wires, transistors,
capacitors, resistors

000-209 Intro to CS. 5/Mother 11
Random Access
Memory (RAM)
chips.
Expansion slots
Motherboard Picture
Read-only
Memory
(ROM)
chips
Processor chip
(the CPU)

Buses
 A bus is a collection of wires and connectors through
which the data is transmitted.
 A communication pathway connecting two or more
devices
 Three types of buses
 Data bus
 Address bus
 Control bus

Data bus
 Data bus transfers actual data.
 This is the bus which is used to transfer the actual
data to and from the locations.
 Data bus connects the CPU, memory and other
hardware devices on the motherboard.
 The number of wires in the bus affect the speed at
which data can travel between components.
 Each wire can transfer one bit at a time therefore an
8-wire bus can move 8bits of data at a time.
 Bus width is the number of bits that it can carry at a
time.

Address bus
 Address bus Identify the source or destination of data.
 Address bus carries the memory addresses.
 Address bus connects the CPU with the memory.
 The number of lines tells the maximum number of
memory addresses.
 CPU with 8-bit address bus could address 28 = 256
different values

Control Bus
 The control bus carries commands from the CPU and
returns status signals from the devices.
 The control bus provides a two way transfer of data,
instructions and results between the main memory.
 For example if the data is being read or written to the
device the appropriate line (read or write) will be active

Ports
 Each I/O device has a cable with a plug having several
Pins for plugging into a socket called port.
 A port also called an interface is generally provided at
the back of a computer.
 A port provides a direct link with the computer’s common
electrical bus.
 Two types of ports are
 Serial port
 Parallel port

Serial ports
 A serial port provides a connection for plugging a
peripheral device with one data line that carry one bit
at a time and additional lines to carry control signals.
 This method of communication comparatively slow
than parallel Port.
 Example
COM1, COM2 etc.

Parallel ports
 Parallel ports allow 8-bits data at a
time over a cable with eight
separate data lines.
 The cable that connects two
parallel ports contains 25 wires, 8
wires carry data and the remaining
wires carry control signals.
 Parallel port transmit fast flow of
large amount of data.
 Example
LPT1, LPT2 etc.

Memory
 Computer are equipped with storage units called as
memory units. The computer memory can hold
programs and the data for current and future use.
These storage devices can be classified as
 Main memory(RAM, ROM)
 Secondary storage(backing storage)

Processor
 A processor is the logic circuitry that responds to
and processes the basic instructions that drive a
computer.
 The term processor has generally replaced the
term central processing unit (CPU). The
processor in a personal computer or embedded
in small devices is often called a microprocessor.
 Dual core processor
 Quad core processor

Processor
 Dual core : Dual-core refers to a CPU that
includes two complete execution cores per
physical processor. It has combined two
processors onto a single integrated circuit.
 Quad core : A quad-core processor is a chip with
four independent units called cores that read and
execute central processing unit (CPU) instructions
such as add, move data, and branch.

Adapter cards
 Adapter cards allow users to install more powerful
components than those embedded on the
motherboard and the addition of features not originally
available with their systems.
 Types of adapter cards
 Video cards
 Sound cards
 Modem card

Video cards
 Interface between computer and a display device
 Unless a computer has graphics capability built into
the motherboard, the video card is required.
 The CPU, working in conjunction with software
applications, sends information about the image to the
video card. The video card decides how to use the
pixels on the screen to create the image. It then sends
that information to the monitor through output
interface.

Sound cards
 A sound card (also known as an audio card) is
an internal computer expansion card that
facilitates economical input and output of audio
signals to and from a computer under control of
computer programs.

Interface
 Help the user use the computer system productively
 User communicate with computer
 Types of interface
 CLI (command line interface)
 GUI (graphical user interface)

CLI
 A command-line interface (CLI), also known
as command-line user interface, console user interface,
and character user interface (CUI), is a means of
interacting with a computer program where the user (or
client) issues commands to the program in the form of
successive lines of text (command lines).
 Advantages
 More flexible and powerful
 Faster for experienced users
 Can combine commands

GUI
 Also known as Graphical User Interfaces (GUIs)
 Mouse-driven and icon-based
 Windows
 Are allocated to the use of a particular program or
process
 Contain a title bar, menu bar, and widgets
.

14-29
GUI Interface – Windows XP

GUI vs. CLI
GUI
 Advantages
 Easy to learn and use
 Little training
 Amenable to multi-tasking
 Disadvantages
 Harder to implement
 More HW/SW requirements
 Requires lots of memory
 SW is complex and difficult to
write
CLI
 Advantages
 More flexible and powerful
 Faster for experienced users
 Can combine commands
 Disadvantages
 More difficult to learn and use
Important

Itc lec 3 Ip cycle , system unit, interface

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