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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