Transcript Document

COMPUTER
SCIENCE PROJECT
WORK FOR III
UNIT TEST
MADE BY: AMIT KUMAR
BHIM KUMAR
CHITRANJAN
GUIDED BY:
MR. LOKESH SAINI
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History Of
Computing
Computer Hardware
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Overview
Computer
Development
Computer architecture
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Introduction
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Computer is arguably the most important tool in the
areas of engineering, science, business etc. etc.
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Data acquisition and analysis
Simulation
Embedded applications
 Process control
 Condition monitoring and fault diagnosis systems
 Automatic testing equipment
 Robotics
 Telecommunications
Productivity software (word processing, spreadsheets,
databases, presentation) etc……………
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Computer development
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The Abacus- Babylonia-4th century B.C.
The Difference Engine- Charles Babbage 1822
Vacuum tube - John Ambrose Fleming 1904
The ENIAC (Electronic Numerical Integrator and Computer)-1945
 Used 17,478 vacuum tubes
 Too late for WW-II, but was used in the cold war to perform
calculations to build a hydrogen bomb
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City of Philadelphia reportedly experienced brown-outs when
ENIAC drew power at its home at the the University of
Pennsylvania
(http://www.pbs.org/wgbh/aso/databank/entries/dt45en.html)
Was not a general purpose computer: programming meant rewiring
with punch cards and switches
One of ENIAC's greatest feats was in showing the potential of what
could be accomplished in the future
Transistor -
Nobel prize in physics in 1956
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Integrated Circuit (chip) -
Jack
Kilby 1958 (Nobel prize in physics in 2000)
First commercially available IC’s developed
by Texas Instruments and Fairchild
semiconductor corp.
Generations of IC’s:
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Apple I computer (1976)
Small scale integration - 1965
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Up to 100 devices on a chip
Medium scale integration - to 1971
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100-3,000 devices on a chip
Large scale integration - 1971-1977
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3,000 - 100,000 devices on a chip
Very large scale integration - 1978 to date
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100,000 - 100,000,000 devices on a chip
Ultra large scale integration
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Over 100,000,000 devices on a chip
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Moore’s Law: Number of transistors on a
chip will double every 18 months.
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Computer Architecture
Central
Processing
Unit
Main
Memory
Systems
Interconnection
Input
Output
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Components of a Computer System
Storage
(External memory)
input/output
central processing unit
Main Memory
(RAM)
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Computer Components
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Component description
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Central Processing Unit (CPU) or microprocessor,
controls the operation of the computer and performs
its data processing functions
Main memory - also called internal memory stores
instructions and data. Memory is partitioned into
separate instruction and data spaces
Input/output (I/O) – moves data between the
computer and its external environment
System interconnection – some mechanism that
provides for communications among the CPU, the
main memory, and the I/O devices
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Structure of the CPU
storage
input/output
control unit
ALU
registers
registers
flags
cache
memory
memory
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Components of the CPU
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Arithmetic and Logic Unit (ALU): processes the data
in the registers according to instructions issued by the
control unit. Performs arithmetic (addition, subtraction,
etc..) and logical (comparison) operations
Registers: provides temporary storage for data and
instructions. It handles instructions and data at 10 times
the speed of cache memory. Registers facilitate the
movement of data and instructions between RAM, the
control unit and the ALU
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Control unit registers:
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The instruction register contains the current instruction being
executed
The program register (instruction pointer) contains the RAM
address of the next instruction to be executed
ALU registers
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The accumulator register stores the result of ALU operations
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Internal CPU interconnection: some mechanism that
provides for communication among the control unit, ALU, and
registers
Control Unit: controls the operation of the CPU and hence the
computer. Interprets instructions, moves data to/from memory
and registers, instructs ALU to perform certain operations,
increments instruction pointer, etc. During program execution,
instructions in a program are moved from the RAM into the
control unit, where it is decoded and interpreted by the decoder
Flags: 1-bit memory, or 1-bit registers and hold information on
what has recently happened in the CPU. These are set to 1 or 0
depending on the results of internal operations such as results
of ALU operations (zero or negative result) or external
operations such as interrupts (commands that tell the processor
to stop execution and wait for further instruction)
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Cache Memory: Small fast memory that improves CPU’s
efficiency. Increases computer throughput, and is a high-speed
holding area for program instructions and data. It holds only
instructions and data that are likely to be needed by the CPU.
While programs are running on the computer, the same data or
instructions might be needed frequently. In such cases, the
processor first checks the cache memory for the data or
instructions, thereby reducing the need for frequent access to
the RAM and speeding up the processing
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Microprocessor System Buses
Control Bus
RAM
ROM
Microprocessor
(CPU)
Data Bus
Address Bus
Input/Output
(I/O)
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System Buses
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A BUS is an internal communications path consisting of a
number of lines connecting the system components
Control bus –The control bus synchronizes system events like
memory access, system interrupts, I/O, etc.
Address bus – Source and destination addresses are sent over
the address bus to identify a particular location in memory or
input/output port.
Data bus – two way path for transferring data and instructions
in and out of the microprocessor
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Main Memory
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A collection of cells
Each cell has an address and a value
Random Access Memory (RAM)
Cells can be accessed randomly
Ram is volatile
All data stored in binary format
Bit, byte and word are the unit of data
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Main Memory
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RAM – Random Access Memory. Temporary read/write memory.
Applications are typically loaded into RAM during computer use.
Types of RAM include:
 SRAM (static) , DRAM (dynamic ), EDO RAM (extended data
out) , SDRAM (synchronous dynamic-most new PC’s are
equipped with this RAM which is able to synchronize itself
with the processor, enabling data transfer at more than
twice the speed of previous RAM technologies)
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SRAM is called static because the memory retains its contents as long
as power is supplied-It does not have to be periodically refreshed as in
DRAM. It is faster than DRAM (The contents of the memory can be
read much faster), however is more expensive and is larger in size
DRAM is called Dynamic RAM because the memory content needs to be
refreshed periodically (every few milliseconds) due to leakage of
electrical charge. It is slower than SRAM, but cheaper and smaller in
size
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CPU-Memory Interaction
Fetch-execute cycle
0
LDA 14
1
ADD 15
Assume a is stored in 14
and b is stored in 15
Program
2
STA 14
3
HLT
….
……
14
10
14
17
15
7
15
7
a= a + b
Result
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ROM – Read Only Memory. ROM can typically be
written once, but read many times. It is used to store
BIOS (Basic Input/Output System-helps to load and
locate an operating system), external to
microprocessor, and computer instruction sets,
internal to microprocessor
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The contents of the ROM are hard wired by the
manufacturer in a typical ROM chip. When you turn the
computer on, ROM automatically prepares the computer
system and loads the initial display screen prompt
A variation of ROM is PROM (Programmable Read Only
Memory), in which the user can load programs and data that
are read only. This can be done with device called a PROM
programmer. Writing to a PROM destroys the internal links,
so a basic PROM can only be programmed once
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EPROMs (Erasable Programmable Read Only Memory) is a
variation of PROM, and is rewritable. It can be erased by
exposing the chip to ultraviolet light. It can then be
programmed with an EPROM programmer
Flash memory is a type of PROM that can be easily altered
by the user. They are also called EEPROMs (Electrically
Erasable Read Only Memory) because they can be
electrically erased then written on to (flashed) without
having to take them out of the computer, and without using
ultraviolet light.
Since RAM can be read faster than most ROMs, the
frequently used content of the ROM is sometimes copied to
RAM (shadowed)
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Secondary Storage
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Magnetic disk
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Optical media
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Hard disk (File, Directory, Folder)
Floppy disks
Zip disks
CD (680 MB)
DVD (4.7 GB)
Magneto-optical disks (Pinnacle drives)
Magnetic tape (used primarily for long term
archive)
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Hard Disk Drive Basics
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Input/Output
Some Input Devices
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Keyboard
Keypad
Mouse
Voice activation
Touch screen
Digitizers and pen-based (stylus) systems
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Some Output Devices
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Monitor
Printer
Speakers
Communication (comm) ports
Modems (both input and output)
Network interface cards (both input and
output)
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Input and Output
Devices and
Systems
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Storage System Issues
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Historical Context of Storage and I/O
Secondary and Tertiary Storage Devices
Storage I/O Performance Measures
Queuing Theory
Processor Interface Issues
I/O Buses
Redundant Arrays of Inexpensive Disks (RAID)
File Systems
I/O Benchmarks
File System Performance
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Input device is a tool used to capture information and commands
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Examples include:
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Keyboard
Point-of-sale (POS)
Microphone
Mouse
Pointing stick
Touch pad
Touch screen
Bar code reader
Optical mark recognition (OMR)
Scanner
IT Fundamentals
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Types of input
IT Fundamentals
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Input Devices
Most obvious = human + KEYBOARD
Need to be: Accurate, reliable and easy to
use, fast
Human and keyboard is the most used input device
Machines make better input devices….
DIRECT ENTRY,
or
SOURCE DATA AUTOMATION.
IT Fundamentals
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Examples of Direct Entry Input Devices
Scanners
MICR : Used with cheques OMR : Tattslotto & TAB
OCR : Scan type-written pages….
IT Fundamentals
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Examples of Direct Entry Input Devices
Barcode Readers:
Sit-in-the-Counter type
Reads standard or customised barcodes
IT Fundamentals
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Input Types
Data Collection Devices:
Web Cams
Video camera whose output displays on a web page
Digital Camera
a.
IT Fundamentals
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Other Input Devices
Sensors
Pointing Devices
Mouse
measures x-y moveent plus whether button is pressed down…
a.
IT Fundamentals
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Other Input Devices
Trackball
- Similar to mouse
Joystick
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games?
Difficult to pinpoint a position
Touch screens
screen 'divided' into areas
area selected by touch
easy to use
cannot have areas too small
screens get dirty (many uses)
TouchPad
Pointing Stick
Light Pen
IT Fundamentals
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Voice Input
Voice Input
IT Fundamentals
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Output
Four common type of output are text, graphics, audio and video.
IT Fundamentals
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Output
Output Devices
Digital signals from computer are converted into human readable form.
Hard Copy
Soft Copy
IT Fundamentals
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Output
Printers
Impact printers
Dot Matrix:
IT Fundamentals
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Output
Non-impact printers
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ink jet
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no physical contact between paper and printing device
3 technologies used:
thermal
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special paper
expensive to run
up to photographic quality…
IT Fundamentals
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Output
Laser
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need enough memory to hold an entire page
600 to 2400 dpi and greater
operates similar to a photocopy machine…
IT Fundamentals
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Output
CRT Monitors
•Raster scan technology
•An electron beam moves back and
forward across the back of the screen
•This causes dots on the front of the
screen to glow, producing an image
•Available in various sizes 15 – 22
inches
•Flat and curved screens
Resolution
•CRT monitors ( 1280 X 1024 pixels)
•High end CRT monitors (2048 X 1536 pixels)….
IT Fundamentals
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Output
IT Fundamentals
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Output
LCD Monitors
•An electric current passes through
the crystals causing them to twist,
block light waves and create an
image.
Gas Plasma Monitors
Very high quality (1080p)….
•Larger screens
IT Fundamentals
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Other Output Devices
Data Projectors
IT Fundamentals
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Other Output Devices
Fax Machine
•Transmits and receives documents over the telephone line
IT Fundamentals
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Other Output Devices
Multifunction devices
•Printer, scanner, copy machine and fax machine all in one
IT Fundamentals
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SECONDARY STORAGE
Control Unit works on programs/data in RAM
POWER OFF ... RAM OFF
Bye Bye Assignment
However blocks of memory can be saved/read on secondary storage.
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SECONDARY STORAGE
Secondary Storage Media and Devices
Floppy Disks
Hard Disks
Tape and Tape drive
Cartridge tape
CD-ROM/DVD/BluRay
Magnetic-Optical drive
PC Cards
Smart Cards
USB Drives
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FLOPPY DISKS:
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3 1/2-inch diskette
Circular piece of plastic
Made up of tracks & sectors
512 bytes in each sector
Size
Type
IBM:
3½ DD
3½ HD
Macintosh
3½ HD
Tracks
Sectors Capacity
80
80
9
18
720KB
1.44MB
1.4MB
eg. for a 3½ disk (high density):
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HARD DISKS
• Made up of platters, cylinders and sectors
• Rotation speed 7200 rpm
• head 'floats' on surface
• bad sectors & head crash
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Hard Disk Vs Floppy Disk
OPTICAL STORAGE TECHNOLOGY
• CD-ROM (compact disk read-only memory)- 650 MB of information
• DVD (digital video disk) - 4.7 gigabytes
• CD-R (compact disk-recordable)
• CD-RW (compact disk-rewritable)
• Magneto-optical (MO) – combines magnetic/optical technology by
changing polarity of spot (1 to 0 etc.)
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CDROM
•Compact Disk Read Only Memory
•high capacity is ideal for storage of
the very large sound, graphics and
video files
• when recording data, laser light
burns pits on CD
• when reading data, pits will not
reflect light (binary bit 0) but lands
will reflect light (binary bit 1)
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Other Storage Devices
Tape
•Thin ribbon of plastic
• Sequential storage – mainly for backup
•Used for longer term storage
USB Flash Drives
• plugs into a USB port
•Small, lightweight
•Storage 4 GB +
•Great for mobile users
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OTHER TYPES OF STORAGE DEVICES
PC cards
• Small, credit card-sized cards that fit into PC Card expansion slots
•Used for storage, communications and additional memory.
• Most often used with portable computers
• Can store more than 300 MB of data
Smart Cards
• Credit card-sized devices that contain a microprocessor
• Microprocessor can store up to 8,000 bytes of information.
• Examples of uses - prepaid telephone card, employee time card
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