Memory and peripherals
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Memory and Peripherals. COSC-100 (Elements of Computer Science) Prof. Juola. Basic Organization. We’ve seen the CPU -- what else? Memory Main/system memory Specialist memory Peripherals Keyboard, monitor, mouse Drives (floppy, hard, pen) Printers, scanners, fish-tank aerators.

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Memory and peripherals l.jpg

Memory and Peripherals

COSC-100 (Elements of Computer Science)

Prof. Juola

Basic organization l.jpg
Basic Organization

  • We’ve seen the CPU -- what else?

  • Memory

    • Main/system memory

    • Specialist memory

  • Peripherals

    • Keyboard, monitor, mouse

    • Drives (floppy, hard, pen)

    • Printers, scanners, fish-tank aerators

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Memory (hum Cats tune)

  • RAM (Random Access Memory)

    • can both read from and write to

    • used for main system storage, typically multiple gigabytes (Gb) at this point

    • cost varies with retrieval speed (and size)

  • Cache [“cash”] memory

    • extremely high speed memory, very expensive, but used as part of CPU for performance

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Losing my memories

  • Problem with RAM -- requires continuous power.

    • DRAM -- “Dynamic” RAM

    • SRAM -- “Static” RAM is misnamed

  • ROM (Read-Only Memory)

    • cannot be written (like CD-ROM!)

    • never loses data, even when power goes out

    • memory values built-in at factory

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Programming ROMs

  • ROM -- programmed at factory

    • build an explicit one or zero circuit, repeat

  • PROM (Programmable ROM)

    • field-programmable by blowing fuses

    • problem : can’t “unblow” fuses (write once)

  • EEPROM (Electrically Erasable PROM)

    • field-(re)programmable, but limited cycles

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Buses and Ports

  • CPU is connected to memory via “bus,” a collection of wires

  • Typical computer has 32-bit bus, meaning 32 data wires

  • Buses also connect to “ports,” electrical sockets for peripheral connections

  • “Peripherals” connect through ports or (internally) direct to bus

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  • Computers are useless if they can’t communicate

  • Data input devices

  • Data output devices

  • Data storage devices

  • Manipulative devices

    • and whatever else your imaginations can dream up. Go wild -- it may be worth $$$

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Input devices

  • Keyboard

  • Pointing devices

    • mouse, TrackPoint, touchpad, trackball

  • Readers

    • bar-code readers, document scanners, light pens

  • Cameras

  • Phone interfaces

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Output devices

  • Video screen/monitor

  • Printer

  • Sound card/speaker

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Storage devices

  • Hard drives

  • Floppy drives

  • ZIP drives

  • Pen drives

  • CD/DVD drives

  • Magnetic tape

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Optical drives

  • Metallic surface has lots of little pits

  • Disk rotates at very high speed

  • Read by laser beam; 32x drives has 32

  • CD-RW use more powerful laser to burn crystal surface, changing reflectivity

  • DVD has much more capacity than CD because pits are closer (and speed is faster)

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Most important peripheral

  • The network card

  • … or the cable modem, wireless card, etc.

  • This needs a lecture all to itself

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Choosing hardware

  • New computers very expensive (Moore’s law, remember?)

  • New computers not reliable

  • Old computers may be obsolete or not supported any more

  • Pg. 93 of textbook lists 9 C’s of criteria

  • Rule of thumb: Buy what you need today.