Computer Peripherals

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 2Computer Peripherals

PeripheralsDevices that are separate from the basic

computer Not the CPU, memory, power supply

Classified as input, output, and storage Connect via

Portsparallel, USB, serial

Interface to systems bus SCSI, IDE, PCMCIA

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 3Computer Peripherals

Storage DevicesPrimary memory

Expanded storageSecondary storage

Data and programs must be copied to primary memory for CPU access

Permanence of dataDirect access storage devices (DASDs)Online storageOffline storage – loaded when needed

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 4Computer Peripherals

SpeedMeasured by access time and data

transfer rate Access time: average time it takes a

computer to locate data and read itmillisecond = one-thousandth of a second

Data transfer rate: amount of data that moves per second

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 5Computer Peripherals

Hierarchy of StorageDevice Throughput Rate

CPU Registers

Cache Memory (SRAM) 15 to 30 nanoseconds

Conventional Memory (DRAM) 50 to 100 nanoseconds

Expanded Storage (RAM) 75 to 500 nanoseconds

Hard Disk Drive 10 to 50 milliseconds 600 to 6,000 KB/sec

Floppy Disk 95 milliseconds 100 to 200 KB/sec

CD-ROM 100 to 600 milliseconds 500 to 4,000 KB/sec

Tape .5 and up seconds 2,000 KB/sec (cartridge)

Typical Access Times

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 6Computer Peripherals

Secondary Storage DevicesHard drives, floppy drives

CD-ROM and DVD-ROM drivesCD-R, CD-RW, DVD-RAM, DVD-RWTape drivesNetwork drives

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 7Computer Peripherals

Magnetic DisksConsist of one or more flat, circular

platters made of glass, metal or plastic and coated with a magnetic substance.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 8Computer Peripherals

Magnetic Disks (cont.)Track – circle

Cylinder – same track on all plattersBlock – small arc of a trackSector – pie-shaped part of a platterHead – reads data off the disk

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 9Computer Peripherals

Magnetic Disks (cont.)Head crashNumber of bits on each track is the same!

Denser towards the center.CAV – constant angular velocity

Spins the same speed for every trackHard drives – 3600 rpm – 7200 rpmFloppy drives – 360 rpm

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 10Computer Peripherals

A Hard Disk Layout

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 11Computer Peripherals

Cutaway of a floppy disk

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 12Computer Peripherals

Locating a Block of DataAverage seek time: time

required to move from one track to another

Latency: time required for disk to rotate to beginning of correct sector

Transfer time: time required to transfer a block of data to the disk controller buffer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 13Computer Peripherals

Magnetic DisksData Block Format

Interblock gapHeaderDataFormatting disk

Disk InterleavingDisk Arrays

RAID – mirrored, striped

Disk Interleaving

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 14Computer Peripherals

RAID (striping)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 15Computer Peripherals

RAID (mirroring)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 16Computer Peripherals

Magnetic TapeOffline storageArchival purposesDisaster recovery

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 17Computer Peripherals

QICCan hold 120 MB to 25 GB of

uncompressed data.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 18Computer Peripherals

DATData on DAT cartridges are

very tightly packed, using a read/write head that rotates at a high speed to pack the tape much more tightly with data.

Very tiny but have capacities of 2GB and up.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 19Computer Peripherals

Optical StorageA direct access disk written and read by

light. CD, CD-ROM, DVD-ROM and DVD-Video are read-only optical disks that are recorded at the time of manufacture and cannot be erased.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 20Computer Peripherals

Types of Optical StorageCD-ROMDVD-ROMWORMMagneto optical disks

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 21Computer Peripherals

CD-ROMRead-only removable medium with large

data storage capacity. Data storage is similar to magnetic disk. Laser beam is reflected off the pitted

surface of the disk as a motor rotates the disk.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 22Computer Peripherals

Layout: CD-ROM vs. Standard Disk

CD-ROM Hard Disk

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 23Computer Peripherals

DVD-ROMSimilar to the CD-ROM technology.Uses laser with a shorter light wavelength

to allow tighter packing of the disk.Total capacity: 17GB

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 24Computer Peripherals

WORM DisksWrite-once-read-many timesSimilar to the CD-ROM technologyMedium can be altered by using a medium-

powered laser to blister the surfaceData stored in concentric tracks, sectored

like a magnetic disk

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 25Computer Peripherals

Magneto-Optical DisksCombine optical and magnetic disk

technology. Share advantages of optical disk:

capacity, reasonable cost & removabilitytogether with the read/write capability of magnetic disks.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 26Computer Peripherals

Magneto-Optical Disks (cont.)May be stored near magnets.Limitation: have a much longer seek time

& a slower transfer rate than magnetic disks.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 27Computer Peripherals

Magneto-Optical Disks (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 28Computer Peripherals

DisplaysImages made up of thousands of individual

pixels or picture elementPixel: The smallest addressable unit on a

display screen or bitmapped image. Screens are rated by their number of

horizontal and vertical pixels 1024x768 means 1024 pixels are displayed

in each row, and there are 768 rows (lines).

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 29Computer Peripherals

Simplest Pixel Representation

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 30Computer Peripherals

Display ScreenScreen size: measured

diagonallyResolution: minimum

identifiable pixel size

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 31Computer Peripherals

Displays Screen (cont.)How to select a PC display screen:

Acceleration and multimedia Monitor size and resolutionLCD or CRT

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 32Computer Peripherals

Acceleration & MultimediaPlacing drawing functions into the circuits

of the display adapter speeds up rendering on screen.

Adding graphics accelerator & video accelerator cards

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 33Computer Peripherals

Acceleration & Multimedia

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 34Computer Peripherals

Monitor size & resolutionStandard resolutions:

640x480800x600

1024x7681280x10241600x1200

The higher the resolution, the more material is viewable on screen.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 35Computer Peripherals

Displays Screen

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 36Computer Peripherals

Color and DisplaysPixel color is determined by intensity of 3 colors

– Red Green Blue or RGBRGB: The computer's native color space.It is also the color system for capturing images

and displaying them. Human eyes are sensitive to red, green and

blue, and all colors are perceived as a combination of the R, G and B.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 37Computer Peripherals

CRT Cathode Ray Tube

A vacuum tube used as a display screen in a computer monitor or TV.

The viewing end of the tube is coated with red, green and blue phosphors dots, which emit light when struck by electrons.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 38Computer Peripherals

CRT

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 39Computer Peripherals

Raster scanDisplaying or capturing a video image line by line from

left to right.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 40Computer Peripherals

LCD – Liquid Crystal DisplayA display technology that uses rod-shaped

molecules (liquid crystals) that flow like liquid and bend light.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 41Computer Peripherals

LCD (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 42Computer Peripherals

Plasma DisplayGas discharge displayUses tiny cells lined with phosphor that are

full of inert ionized gas

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 43Computer Peripherals

Plasma Display (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 44Computer Peripherals

PrintersDots vs. pixels

300-2400 dpi vs. 70-100 pixels per inchDots are on or off, pixels have intensities

TypesTypewriter / Daisy wheels – obsoleteDot matrix – usually 24 pins, impact printingInkjet – squirts heated droplets of inkLaserjetThermal wax transferDye Sublimation

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 45Computer Peripherals

PrintersGeneral Categories

Serial Printers (Character Printers)Line PrintersPage Printers

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 46Computer Peripherals

Serial PrinterPrints one character at a time moving

across the paper.Eg. serial dot matrix printer, with speeds

ranging from 200 to 400 cps (90 to 180 lines per minute)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 47Computer Peripherals

Dot MatrixUses hammers and a ribbon to form

images out of dots. Forms characters and graphics by

impacting a ribbon and transferring dots of ink onto the paper.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 48Computer Peripherals

Dot Matrix (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 49Computer Peripherals

Line PrinterPrint a line at a time from approximately

400 to 2,000 lpmEg. Line Matrix printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 50Computer Peripherals

Line Matrix

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 51Computer Peripherals

Line Matrix (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 52Computer Peripherals

Page PrinterPrints a page at a time from four to more

than 800 ppm. Eg. Laser Printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 53Computer Peripherals

Laser PrinterUses a laser and the electrophotographic

method to print a full page at a time. The laser "paints" a charged drum with

light, to which toner is applied and then transferred onto paper.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 54Computer Peripherals

Laser Printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 55Computer Peripherals

Other PrintersInk jetDye sublimationThermal Wax transfer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 56Computer Peripherals

Ink JetPropels droplets of ink directly onto the

medium. Makes use of an ink jet cartridge

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 57Computer Peripherals

Ink Jet Printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 58Computer Peripherals

Dye sublimation printerProduces continuous-tone images that

look like photographic film. Also called a "thermal dye printer”.The print cartridge contains a cellophane

ribbon with panels of dye the same size as the page to be printed.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 59Computer Peripherals

Dye sublimation printer (cont.)

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 60Computer Peripherals

Dye Sublimation Printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 61Computer Peripherals

Thermal wax transfer printerUses the same printing mechanism as a

dye sublimation printer.Instead of using a dye, it melts dots of

wax-based ink that adhere to almost any kind of stock, from ordinary paper to complex synthetics and film.

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 62Computer Peripherals

Thermal wax transfer printer

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 63Computer Peripherals

Other Computer PeripheralsScanners

Flatbed, sheet-fed, hand-heldLight is reflected off the sheet of paper

User Input DevicesKeyboard, mouse, light pens, graphics tablets

Communication DevicesTelephone modemsNetwork devices

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 64Computer Peripherals

Scanner

Englander, The Architecture of Computer Hardware and Systems

Software An Information Technology Approach, 3rd ed., 2003 65Computer Peripherals

Telephone modems