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Lecture notes by Mr.Ravi
KYUEM
Hardware
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Agenda
DefinitionsComputer ComponentsHow Information is
RepresentedHow Information is ProcessedTypes of Computers
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Computer Concepts
An electronic device that takes data as input, transforms the data by executing a stored program, and outputs information.
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Performance Criteria
Functionality Speed, capacity, price, reliability, operating
conditionsEase of Use
Quality of user interface, ease of learning, portability
Compatibility Conformance to standards, interoperability
Maintainability Modularity, scalability, flexibility
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How does data get into the computer?
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Input Devices – Manual Entry(converts data into electronic format for input)
Manual Entry Pointing Devices
Mice, trackballs
Keyboard Touch Screens Punched Cards
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Input Devices – Automated Entry
Audio Input Devices Voice recognition
Magnetic Ink Character Recognition (MICR)
Optical Character Recognition (OCR) Bar Codes
Digital Scanners (image processing)Pen Based InputSensorsBiometric Systems
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How does data get out of the computer?
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Output Devices
Output devices produce the most visible aspect of computing: the reports, charts, sounds, and images that the users consult to make decisions, to complete communications, or to engage in entertainment.
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Output Devices(converts electronic data into a form intelligible to
humans)
PrintersScreenAudio Output DevicesMicrofilm / Microfiche
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How is data represented once it is in the computer?
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Representing InformationData is stored using Binary Digits
BITS
Binary means 2 states represented by 1 (on) or 0 (off)
Does the computer actually store a bunch of 1’s and 0’s ????? more on this later….
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Nibbles, Bits, and BytesBIT (one digit)
NIBBLE (4 bits, or 1/2 a byte)
BYTE (8 bits) every letter, symbol, or number can
be represented by one byte
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Bits and Bytes
Kilobyte (KB) – Approximately 103 one thousand bytes
Megabyte (MB) – Approximately 106 one million bytes
Gigabyte (GB) – Approximately 109 one billion bytes
Terabyte (TB) – Approximately 1012 one trillion bytes
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How is data physically stored in the computer?
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CPU & PRIMARY STORAGE
CPUCPUPRIMARYPRIMARY
STORAGESTORAGE
DATA BUSDATA BUS
ADDRESS BUSADDRESS BUS
CONTROL BUSCONTROL BUS
INPUT
DEVICES
OUTPUT
DEVICES
SECONDARY
STORAGE
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Storage Devices
Primary Storage (main memory)
temporary storage of data and instructions uses semi-conductor chips data is processed at speed of light located next to the CPU
Secondary Storage long term storage of data and instructions data is processed with electro-mechanical
components
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Primary Storage
RAM – primary memory Random Access Memory - will be erased
when power is turned off (volatile)
ROM Read Only Memory – preprogrammed,
for booting up the computer
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Other Memory
Cache Memory – is a high speed area that the CPU can access quickly and can be located on the microprocessor chip or on the motherboard
Video Memory – temporarily stores video images before being displayed on the screen.
Flash Memory – nonvolatile, used to supplement RAM or secondary storage
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Secondary Storage
Magnetic Tape
Magnetic Disk
Optical Disks e.g. CD’s
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Magnetic Tapes
oldest, least expensiveSpool of plastic tape, just like
your music tapesstorage method: sequentialSLOW !!!What type of applications
would be appropriate?
HEADER IBG BLOCK 1 BLOCK 2 BLOCK 3
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Magnetic Disks
DASD -Direct Access Storage DevicesTypes
Hard Disks – array of steel disks used for large computer systems
RAID – redundant array of inexpensive disks
Floppy Disks – removable disk for PCstorage method : track methodWhat types of applications would be
appropriate?
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TRACKS AND SECTORSTRACKS AND SECTORS
EACH TRACK HOLDSEACH TRACK HOLDSSAME AMOUNT OF DATASAME AMOUNT OF DATA
SECTORSECTOR
TRACKSTRACKS
DIRECTORY ON TRACK 0DIRECTORY ON TRACK 0
STARTSTARTOFOFTRACKSTRACKS
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CYLINDER 10: TRACK 10 (TOP AND BOTTOM OF EACH DISK)CYLINDER 10: TRACK 10 (TOP AND BOTTOM OF EACH DISK)
DISK 1DISK 1DISK 2DISK 2DISK 3DISK 3DISK 4DISK 4DISK 5DISK 5
READ/WRITEREAD/WRITEHEADSHEADS
Hard Disk Pack
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Magnetic Disks
Disk Access Time How long does it take to
read/write to the disk
Recording Density How much stuff can you fit
per square inch
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Optical Disks
CD-ROM (Compact disk – read only memory)
WORM (Write once – read many times)
CD-R (CD – recordable)
CD-RW (CD – rewritable)
DVD (digital video disk)
What types of applications would be appropriate?
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Are there really a bunch of 1’s and 0’s inside the computer?
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How is the data physically stored?Represented by 1 (on) or 0 (off)Primary Storage
Uses semi-conductor chips Electricity conducting in that bit address = on Electricity not conducting in that bit address = off
Magnetic media Uses magnetism Direction of magnetism in the bit address
determines on/offCD ROM
Uses lasers to burn pits in the surface of the CD depth of pit in that bit address determines on/off
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How does the computer process data?
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How data is Processed
MotherboardCentral Processing Unit (CPU)
Control Unit Arithmetic Logic Unit (ALU) Primary Storage (RAM)
Clock
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System Unit and Motherboard
The system unit for a personal computer contains the electrical and hardware components that make the hardware work. Power Supply, Voltage Regulator, Surge
Protector and Uninterruptible Power SupplyThe motherboard is the main circuit
board that supports and connects the various hardware components
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System Unit and Motherboard
The motherboard provides connections between processors, memory units, and sockets or expansion slots.
Expansion slots are where additional circuit boards can be plugged in.
Each expansion slot has 1 external port where a peripheral device can be connected.
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CPU
The Central Processing Unit (CPU) of a computer is a general purpose processor. Considered the brain of the computer Semi-conductor silicon chips Intel, AMD, TI, NEC
Processor Control Unit ALU
RAM
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Control Unit
controls and coordinates the other components of the computer
moves data in and out of primary storage
instructs the ALU which command to execute
sends output to the printer/screen/storage
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Arithmetic Logical Unit
performs arithmetic and logical operations on data
adds, subtracts, multiplies, compares
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Machine Cycle
Instruction Cycle instruction received from primary storage and
decodedExecution Cycle
required data located instruction executed results stored
Computers are measured in Cycles per Second (MIPS or Teraflops)
The Clock sets the pace of the instructions
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How fast is a computer?Cycle Time
Measured in MIPS – millions of instructions per second (also known as Megahertz)
slow (milliseconds) medium (nanoseconds) fast (picoseconds) Also measured in FLOPS – floating point
operations per second
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Microprocessor Technology and Speed
Affected by size of wordhow many bits the processor can read
Affected by width of busHow many bits can travel along the bus
Affected by Clock Speed Reduced Instruction Set Computing (RISC)
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How are computers classified?
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Types of Computers
Microcomputers desktop/portables (64MB of RAM)
Workstations graphics / mathematical processing
Minicomputers / Servers medium size (10 MB - 1 GB of RAM)
Mainframes very large (>1 Gigabyte of RAM)
Supercomputers For scientific, mathematic processing
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Your Tasks Download lecture notes from the
following website
http://groups.yahoo.com/group/online_discussion_group/
Go to files section and check for Hardware notes Please see next slide for hint
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Your Tasks
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