Transcript Chapter 2: Processing Hardware

Processing Hardware
Chapter 2
Turning Data into Something You
Can Use
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Overview
• Data and program representation
• Processor, main memory, registers
• RAM capacity, word size,
processor speed
• Microcomputer
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Computers
• Programmed to learn and adapt
• High costs slowed initial adoption
• More than 15 billion microprocessors
and microcontrollers in use at the turn of
the century
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Data and Program Representation
• Binary system
• Two common schemes
– EBCDIC
– ASCII
• New scheme
– Unicode
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The Parity Bit
• A parity bit is a check bit
• It is an extra bit attached to the end of a
byte to check accuracy
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Capacity
• Bit
– 0s and 1s
• Byte
– 8 bits
• Kilobyte
– about 1000 bytes
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Larger Capacity
• Megabyte
– about one million bytes
• Gigabyte
– about one billion bytes
• Terabyte
– about a trillion bytes
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Processor
• Information
– manipulates data into useful information
• Knowledge
– results in reasoned analysis and
applications
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Processors, Main Memory, and
Registers
• Processor
– control unit
– arithmetic/logic unit (ALU)
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Logical Operations
• Logical operations in the
ALU are simple
comparisons such as =, <,
>, <=, or >=
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Boards and Chips
• Circuit boards
• Chips of silicon
• Use aluminum or copper to
conduct electronic messages
• Semiconductor
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Specialized Systems
• Coprocessors
– math
– graphics
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Future
• PC on a chip
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CISC, RISC, MPP
• CISC (“sisk”)
– complex instruction set, serially executed
– most mainframes and PCs
• RISC (“risk”)
– reduced instruction set, serially executed
– cheaper and faster
– shift some work to software
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MPP
• Massively parallel processing
(MPP)
– spreads calculations over many
computers or processors
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Main Memory
• Primary storage
– RAM (random access memory)
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•
•
•
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holds data
instructions
processed data for output
is volatile
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Main Memory Facts
• Contents temporary
• Capacity varies
according to
installed amount of
memory chips
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Registers
• High speed circuitry areas
– store data and provide work areas
– dedicated by function
• addition register
• subtraction register
• storage register
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Machine Cycle
• Compares a series of operations to perform
a single program instruction
• During the instruction cycles, or I-cycles,
– control unit fetches instructions from main
memory
– decodes or interprets instruction
• During execution cycle, or E-cycle,
– executes and stores result
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RAM Capacity, Word Size,
Processor Speed
• RAM capacity
– software determines capacity needed
– older computers may not have enough
– computer’s RAM capacity is limited by the
capacity of the motherboard
• Measured in megabytes, gigabytes, and
terabytes
– PCs to servers to mainframes, based on
programs and load capacity
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Word Size
• Number of bits computer can hold in its
registers
– sent through local bus
• 32-bit
– most 486 PCs
• 64-bit
– common PCs in CISC format
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Processing Speed
• System clock controls speed of operations
• Speeds measured in megahertz (MHz) are
common
• Gigahertz (GHz) predicted in the near
future
• MIPS and FLOPS not commonly used
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Focus on PC Purchasing
– System unit
• Hard drive
• Floppy drive
(except iMac)
• Power supply
• Motherboard
• Microprocessor
• Ram
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• ROM
• Cache
• VRAM
• Ports
• Expansion
boards
• Bus lines
• PC slots
• PC cards
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Power Supply
• Power supply
– protected by power surge protector or
uninterrupted power supply unit (UPS)
– voltage capacity can affect the ability to
support internal parts
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Motherboard
• Also called system board
• Includes CPU, memory chips (RAM,
ROM), ports, coprocessors if not integrated
on CPU, expansion slots
• Some boards have integrated sound,
controller cards, and graphics
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Microprocessor
• Intel (PC)
– X86
– Celeron
– Pentium
MMX
– Pentium II/III
• AMD (PC)
– K6-2
– K6-3
– Athlon
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Other Microprocessors
• Motorola
(Mac)
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–
–
–
–
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68000
68020
68040
PowerPC 601
PowerPC 604
PowerPC 620
PowerPC 750
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Compatibility
• Most software is backward compatible with
new chips
• The older the hardware, the less the likely
that it will install easily and function
completely in new systems
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The Truth About RAM
• Generally, more is better
– must match with motherboard and CPU
capabilities
• Software vendors traditionally understate
software (RAM) requirements for a smooth
operation of their software
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A Suggestion
– A computer running Microsoft Office 97 should
have a minimum 32MB RAM for smooth
performance
– Microsoft Office 2000 needs 64 to 128 MB
RAM
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ROM Chips
• Read-only memory
(ROM)
• Also known as firmware
• Helps boot the system
• BIOS
– Basic Input Output System
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Other ROM
• PROM
– programmable ROM
• EPROM
– erasable programmable ROM
• EEPROM (flash)
– electronically erasable programmable ROM
– can be rewritten without special equipment
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Other Forms of Memory
• Cache memory (“cash”)
– quick access memory, internal or external to the
processor
– bridge between the processor and RAM
– including pipeline-burst simultaneous
read/write
• Video memory
– VRAM (“vee-ram”)
– some graphic cards use other types of RAM
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Ports
• External socket
– front or back of system unit
• Parallel
– printers, some Zip drives, some scanners
• Serial port (RS-232)
– modems, scanners, mice
• Video adapter
– digital and analog, single or dual monitor
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More Ports
• SCSI: small computer system interface
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fast
connected in daisy-chain fashion
originally used in Macs
can be internal or external
hard drives, tape backups, scanners, CD
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Less Common Ports
• Game ports
– joystick
• Infrared
– often used for keyboards, mice,
and printers
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Expansion Slots
• Bus slots
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–
–
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for expansion cards and adapter cards
memory
video
graphics
controller
internal modem
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Bus Designs
• ISA (“eye-suh”): Industry Standard
Architecture
– does not share common resources
– 16-bit
• PCI: peripheral component interconnect
– some cards do share resources, such as IRQs
– 64-bit
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More Buses
• EISA (“ee-suh”) enhanced industry standard
architect
– 32-bit
• PCMCIA: Personal Computer Memory Card
International Association
– for PC cards on portable computers
• modems, hard drives, memory, Ethernet cards
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Newer Bus
• USB
– Universal Serial Bus
– printer, scanner, digital camera, joystick,
monitor
– easy connection
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Newest Bus
• AGP: Advanced Graphics Port
– dedicated for video use
– speed and access to memory and CPU continue
to increase
– more than double PCI rates
– standards include 2X AGP, 4X AGP
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Standards and Options
• New boards often have ISA and PCI slots so
close together that both cannot be available
for expansion at the same time
• The PC-2000 computer standard calls for no
ISA slots
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Future Processing Technologies
• Gallium arsenide
– better conductor, fewer circuits than silicon
• Superconductors
– electricity flows without resistance
– 100 x faster
– refrigerated system units already on market
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More of the Future
• Opto-electronic processing
– use of light
– in common with fiber optics
• Nanotechnology
– nanometer = 1 billionth of a meter
– molecules used to transform data or perform
tasks
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Future
• Biotechnology
– use of bacteria for
on/off signals
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