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Periferal Devices

Department of Computer Science

Faculty of Civil Engineering, Brno University of Technology

Information Technology 1

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Global schema

CPU RAM

controlNPeripheraldeviceN

control1Peripheraldevice1

internal bus

I/O bus

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I/O bus schema – I/O ports

i/O instructions

out A,3F8

in 3F7,B

CPU

I/O ports

controlNPeripheraldeviceN

01001011

10000010

01001111

10101011

00001000

0001

0010

0011

0100

0000

I/O Addr Content

Bi-directionalcommunication

control1Peripheraldevice1

IRQ1

IRQN

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Input/Output Processing

1. Programmed I/O

• The CPU executes a sequence of instructions, being in direct control of the I/O operations (sensing device status, read/write commands, etc.).

• When the CPU issues a command to the I/O module, it must wait until the I/O operation is complete.

• A lot of wasted time, because the CPU is much faster than devices.

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Input/Output Processing

2. Interrupt-driven I/O

•IRQ – Interrupt Request

•After issuing an I/O command, the CPU has not to wait until the operation has finished; instead of waiting, the CPU continues with other useful work.

•When the I/O operation has been completed, the I/O module issues an interrupt signal on the bus.

•After receiving the interrupt, the CPU moves the data to/from memory (or I/O ports), and issues a new command if more data has to be read/written.

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Input/Output Processing

2. Interrupt-driven I/O – cont'd

Advantage over programmed I/O:

• Instead of waiting the operation to be finished, the CPU can do some useful work.

Still a problem:

• If a large amount of data have to be moved, this technique is still not efficient, because the CPU has to take care of each data unit separately, to move it to/from memory.

• Handling the interrupt also takes some time.

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Input/Output Processing

3. Direct Memory Access (DMA)

• An additional module on the system bus, the DMA module (controller), takes care of the I/O transfer for the whole sequence of data.

• The CPU issues a command to the DMA module and transfers to it all the needed information.

• The DMA module performs all the operations – it transfers all the data between I/O module and memory without going through the CPU.

• When the DMA module has finished, it issues an interrupt to the CPU.

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Input/Output Resources

Each controller can occupy some resources:

•I/O ports

•Memory range

•number of IRQ

•DMA channel

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Device Manager – MS Windows

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Disk memories

Data structure

After a low-level format, the disk surface is divided it into tracks and sectors.

The tracks are concentric circles around the central spindle on either side of each platter.

Tracks physically above each other on the platters are grouped together into cylinders which are then further subdivided into sectors of 512 bytes apiece.

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Capacity = NB · NS · NT · NP

NB – bytes per sector (512)

NS – sectors per track

NT – tracks per surface

NP – number of surfaces

Disk capacity

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Floppy disk

diskette 3,5“ HD

write protectionopen – read only,close – read/write

label

type IDmanufact. set DD (720 KB), no windowHD (1440 KB) window

recording window coveredby metallic protection

3½” DS, HD

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•plastic disk coated with thin magnetic layer for storing information

•floppy disks need to be protected against the magnetic field

•before use the formatting process to create the tracks and sectors

•speed of rotation: 300 to 360 rpm

•Floppy Disk Drive – the unit for floppy disk

•FDD controller is integrated direct in mainboard

Floppy disk

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Floppy disk format

diam surfaces tracks sectors capacity

5¼” 2 40 9 360 KB

5¼” 2 80 15 1 200 KB

3½” 2 80 18 1 440 KB

NB = 512 BNS = 18 sectors per trackNT = 80 tracks per surfaceNP = 2 surfaces

Capacity = NB · NS · NT · NP = 512 · 18 · 80 · 2 =

= 1 474 560 B = 1 440 KB (= 1,44 MB?)

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Floppy disk classification

• diameter 3½” 5¼” 8”

• number of magnetic surfaces SS (Single Sided) DS (Double Sided)

• density SD (Single Density) DD (Double Density) QD (Quadruple Density) HD (High Density)

Standard today: 3½” DS HD

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Hard Disk

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Hard disk

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Magnetic head

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Hard disk

• Label HDD (Hard Disk Drive)

• Tracks physically above each other on the platters are grouped together into cylinders

• famous producers:

Western Digital, Seagate, IBM, Quantum, Fujitsu

• HDD controller mainly integrated in the mainboard

Parameters of modern HDs

• capacity – tens GB, access time – few ms (8 ms)

• spin – 5400 to 10000 rpm, transfer rate – tens MB/s

• cache volume – tens MB

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Hard disk

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Hard disk interface

• IDE (Integrated Drive Electronics) – most useful EIDE (Enhanced IDE) – transfer rate 16 MB/s Ultra DMA/33 – transfer rate 33 MB/s Ultra DMA/66 – transfer rate 66 MB/s Ultra DMA/100 – transfer rate 100 MB/s

(Seagate uses instead of Ultra DMA label UATA)

• SCSI (Small Computer System Interface)

– more expensive, applicable for servers types: SCSI, Ultra SCSI, Wide SCSI, Ultra Wide SCSI, LVD SCSI (transfer rate 80 MB/s)

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CD-ROM

• Compact Disc - Read Only Memory

• removable optical storage medium

• standard capacity 650 MB

• Read only

• instead of concentric tracks there is one spiral track of pits from the center of the disc outwards

• the track is divided into the sectors

The pits are typically 0.5 microns wide, 0.83 to 3 microns long and 0.15 microns deep. The space between the tracks - the pitch - is just 1.6 microns. Track density is over 16,000tpi, compared to 96tpi of a floppy disk and the average 400 of a hard disk. Unraveled and laid in a straight line the spiral of data would stretch for four miles.

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CD-ROM drive

• interface IDE (EIDE, ATAPI) or SCSI

• access time ~ 100 ms

• transfer rate:

1x - 150 KB/s,

2x - 300 KB/s,

24x - 3600 KB/s, …

• func. also for audio CD

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Printers

Classification according to a physical principle

• dot (matrix)

• ink (bubble)

• laser

• thermal

• others

Parameters of printers

• cost

• density – DPI (Dots Per Inch)

• speed – chars per sec., pages per minute

• costs per page

beat less technology

beat technology(carbon copy allowed)

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• patterns are created by the series of needle beats, printer head moves above the ribbon

• needles are controlled by electromagnets

• usually 9- a 24-needles per head

• noisy

• quality depends on the ribbon wear

• density 100 - 200 DPI

• low costs

Matrix printers

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quiet

on stream

electromagnet

paper

printer cylinder

needle

spring

ribbon

center holes

Matrix printers

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• similar principle as in dot printers

• the inkdrops incident the paper rather than needles

• speed comparable with matrix printers

• print quality camparable with laser printers

• almost without noisy

• higher costs as in case of the matrix printers

• piezzo and bubble technology

Ink printers

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Laser printers

LaserMirror

toner stack

Charging of cylinder surface

Paper

Cleanedge

iron furnace

Clean paper Paper with toner complete copy

simplified operation principle

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Laser printers

• high quality of printing – resolution 600-1200 DPI,

• high speed – 6 - 40 pages per minute

• without noisy

• high cost

• xerographic paper needed

• during the operation the dangerous ozone is created

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Principles of color printing

Monitor

• aditive color composition

• model RGB (Red, Green, Blue)

• Red + Green + Blue = White

Printer

• subtractive color composition

• model CMY (Cyan, Magenta, Yellow)

• Cyan + Magenta + Yellow = Black

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Color model RGB (monitor)

R G

B

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Color model CMY (printer)

YM

C

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Monitors

Color cathod tube

Delta

Inline

Trinitron

Diagonal – 14”, 15”, 17”, 19”, 21”Resolution – 640x480, 800x600, 1024x768, 1280x1024Refresh rate – 60 - 120 Hz

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LCD display

Liquid Crystal Display

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Other peripheral devices

Keyboard

Mouse (classic, optical, wireless)

Joystick

Audiocard

Network adapter

Plotter

Scanner

Streamer

Modem

Virtual reality components

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• http://www.pctechguide.com

• http://www.howstuffworks.com

• http://www.zive.cz

• White, R.: How computers work. Que, Indianapolis 1999.

• Vrátil, Z.: Postavte si PC. BEN, Praha 1999.

• Horák, J.: Učebnice hardware. Computer Press, Praha 1998.

• Precht, M. – Meier, N. – Kleinlein, J.: EDV-Grundwissen: Eine Einführung in Theorie und Praxis der modernen EDV. Addison-Wesley, 1996.

• Колесниченко, О. – Шишигин, И.: Аппаратные средства РС. «БХВ», Санкт-Петербург 1999.

• Вильховченко, С.: Современный компьютер: устройство, выбор, модернизация. «Питер», Санкт-Петербург 2000.

References