Lecture 3
Computer Organization and Hardware
CSCS100 - Spring 2009 – Forman Christian College
Asher Imtiaz
*Figure Acknowledgements: “How Computers
Work” 6th Ed by Ron White (Illustrated by Timothy
Edward Downs) © Que Corp 2002
*Several of these slides have been adapted and modified from LUMS CS101
course (Dr Sohaib Khan and Dr Arif Zaman), VU CS101 slides (Dr. Altaf A. Khan)
and Peter Norton’s supplementary material.
Goals
•Looking inside the computer
system…
• Parts of a computer system.
Parts of a Computer System
Parts of the Computer System
• Computer systems have four parts
• Hardware
• The physical parts of a computer
• Any part of the computer that you can touch
• Software
• Previous lecture: “A computer does what it is told to do…You
tell a computer what to do by giving it a list of precise,
unambiguous instructions, a computer program”
• Set of instructions to tell the computer what it should do
• Computer Programs are pieces of software
• Data
• Chunks of information in ‘raw’ form.
• Computer organize, process and present data and
information.
• User
• People operating the computer
• Most important part
• Tell the computer what to do
Information Processing Cycle
• Steps followed to process data
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Input
Processing
Output
Storage
Essential Computer Hardware
• Computers use the same basic hardware
• Hardware categorized into four types
• Processing devices
• Memory devices
• Input and output devices
• Storage devices
Organization
Image credit: VU CS101 (Dr Altaf Khan)
Essential Computer Hardware
• Processing devices
• Processing: The procedure that converts raw data into
useful information. To do this, the computer uses two
important components: processor and memory.
• Processor: Brains of the computer
• Carries out instructions from the program
• Manipulate the data, transforms data into information
• Central Processing Unit (CPU) term used to refer to a
computer’s processor.
• In personal computers, processor consists of one or
more specialized chips, called microprocessors (tiny
slivers of silicon or other material etched with many
tiny electronic circuits).
• E.g. Pentium 4, Core2Duo.
Motherboard
• Rigid, rectangular card containing the circuitry that
connects the processor to the other hardware.
• PCB (Printed Circuit Board) made of Fiberglass sheet with
electrical pathways, called traces, etched into it
• System Clock
• Microprocessor
• Read-Only Memory (ROM)
• Random Access Memory (RAM)
• Battery
• Power Supply
• Ports
• Expansion Slots
• Buses
• Address Bus
• Data Bus
Motherboard
Clock
• The computer’s internal clock
• Quartz crystal
• Every tick causes a cycle
• Speeds measured in Hertz (Hz)
• Modern machines use Giga Hertz (GHz)
Bus
• Electronic pathway between components
• Expansion bus connects to peripherals
• Bus connects CPU and RAM, housed on the
motherboard.
• Speed is tied to the clock
• Data bus
• Address bus
USB
• Universal Serial Bus (USB)
• Connects external devices
• Hot swappable
• Allows up to 127 devices
• Cameras, printers, and scanners
Essential Computer Hardware
Memory devices
• Stores data or programs
• Random Access Memory (RAM)
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Like an electronic scratch pad
Stores current data and programs while the CPU works on them
Set of chips, mounted on a circuit board
Volatile
More RAM results in a faster system
The term ‘memory’ is typically used to mean RAM.
256MB – 4GB
• Read Only Memory (ROM)
• Permanent storage of programs, not volatile
• Holds the computer boot directions
• Cache Memory
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Very fast memory
Holds common or recently used data
Speeds up computer processing
Most computers have several caches
Essential Computer Hardware
• Input and output devices
• Allows the user to interact
• Input devices accept data
• Keyboard, mouse, microphone, joystick, trackball,
touchpad, scanner.
• Output devices deliver data
• Monitor, printer (hard copy), speaker
• Some devices are input and output
• Touch screens
• Any other???
Essential Computer Hardware
• Storage devices
• Hold data and programs permanently
• Different from RAM
• Magnetic storage
• Floppy and hard drive
• Uses a magnet to access data
• Optical storage
• CD (Compact Disk, 700MB~80mins of audio) and
DVD (Digital Video Disk, 4.7-17GB) drives
• Uses a laser to access data
• The future? Blue laser disc technology, upto a 100GB
(and more) on one disk.
Computer Ports
The connection point at which we
connect input and output devices
to a computer.
Standard Computer Ports
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Mouse
Keyboard
USB
Serial
Parallel
Modem
Network
Microphone
Speakers
VGA
S-Video
Microprocessor
Image credit: VU CS101 (Dr Altaf Khan)
Microprocessor
• The key element of all computers, providing the
mathematical and decision making ability
• Current state-of-the-art microprocessors (Pentium,
Athlon, SPARC, PowerPC) contain complex
circuits consisting of tens of millions of transistors
• They operate at ultra-fast speeds – doing over a
billion operations every second
• Made up from a semiconductor, Silicon
Microcomputer Processors
• Intel
• Leading manufacturer of processors
• Intel 4004 was worlds first microprocessor
• IBM PC powered by Intel 8086
• Current processors
• Core 2 Duo
• Centrino
• Itanium
• Pentium IV
• Xeon
Microcomputer Processors
• Advanced Micro Devices (AMD)
• Main competitor to Intel
• Originally produced budget products
• Current products outperform Intel
• Current processors
• Sempron
• Athlon FX 64
• Athlon XP
• TurionTM
A Microprocessor System
• Microprocessors are powerful pieces of
hardware, but not much useful on their own
• Just as the human brain needs hands, feet, eyes,
ears, mouth to be useful; so does the
microprocessor
• A microprocessor system is microprocessor plus all
the components it requires to do a certain task
• A microcomputer is 1 example of a
microprocessor system
Micro-controllers
• Micro-controllers are another type of
microprocessor systems
• They are generally not that powerful, cost a few
dollars a piece, and are found embedded in
video games, VCRs, microwave ovens, printers,
autos, etc.
• They are a complete computer on a chip
containing direct input and output capability
and memory along with the microprocessor on a
single chip. Many times they contain other
specialized application-specific components as
well
More on Micro-controllers
• More than 90% of the
microprocessors/micro-controllers
manufactured are used in embedded
computing applications
• In 2000 alone, 365 million microprocessors
and 6.4 billion micro-controllers were
manufactured
Building Blocks of a Microprocessor
• Bus Interface Unit
• Data and Instruction Cache
• Instruction Decoder
• Arithmetic Logic Unit
• Floating Point Unit
• Control Unit
• Registers
Language of a Microprocessor
Instruction Set
• The set of machine instructions that a microprocessor
recognizes and can execute – the only language
microprocessor knows
• An instruction set includes low-level, a single step-at-atime instructions, such as add, subtract, multiply, and
divide
• Each microprocessor family has its unique instruction set
• Bigger instruction-sets mean more complex chips (higher
costs, reduced efficiency), but shorter programs