information technology - introduction to...

Introduction History General architecture Main types The PC: hardware components The software Summary

Information TechnologyIntroduction to Computers

László Kálmán1 Csaba Oravecz1 Péter Szigetvári2

1Research Institute for LinguisticsHungarian Academy of Sciences

2Department of English LinguisticsEötvös Loránd University

Lecture 1. / 12 Sep, 2007

Oravecz, Szigetvári Introduction to Computers


Outline1 Introduction

Computers in general2 Short history3 General architecture

The stored program architecture (von Neumann)4 Main types

Mainframes, mini- and microcomputers5 The PC: hardware components

MotherboardThe CPUStorageMemoryMass storage devicesInput devicesOutput devicesExpansion slotsPorts and protocols

6 The softwareThe BIOSThe operating systemThe boot process











Trust The Computer. The Computer is your friend.

A computer lets you make more mistakes faster than anyother invention, with the possible exceptions of handguns

and Tequilla.Mitch Ratcliffe



The usual useless definitions

A computer is

• an electronic device for the storage and processing ofinformation.

• a machine for manipulating data according to a list ofinstructions known as a program.

• a machine for performing operations on numeric orsymbolic data.



The beginnings

• computer: a person who performed numerical calculations

• ancestors: abacus, Antikythera mechanism

• 1801: Jacquard loom with punch cards



The beginnings

Figure: Jacquard loom with punch cards.



The beginnings

• computer: a person who performed numerical calculations

• ancestors: abacus, Antikythera mechanism

• 1801: Jacquard loom with punch cards

• late 19th c.: large-scale automated data processing withPCs

• first half of 20th c.: sophisticated special-purpose analogcomputers

• direct mechanical or electrical model of the problem as abasis for computation



The middle

• 1940s: several “first digital electronic computers”

• ENIAC (1946): first based on the von Neumannarchitecture



The middle

Figure: ENIAC.



The middle

• 1940s: several “first digital electronic computers”

• ENIAC (1946): first based on the von Neumannarchitecture

• 1950s: valve (tube) driven computers

• 1960s: transistor-based computers

• 1970s–: integrated circuit technology → low enough cost→ personal computers

• today’s computers are exponentially more capable thanpreceding ones (c.f. Moore’s Law)



The end

Figure: A Sentinel.











You don’t have to know how the computer works, just howto work the computer.



Stored program architecture

• four main sections:1 arithmetic and logic unit (ALU)2 control system3 memory4 I/O devices

• connected by bundles of wires (buses) and driven by atimer or clock



Task of components

• ALU: heart and/or brain of computer, performs basicoperations

• memory: stores information; data or instructions

• I/O system: communicates with the outside world• control system:

• reads instructions and data from memory or I/O• provides the ALU with the correct inputs acc. to the

instructions• tells the ALU what operation to perform on inputs• sends the results back to the memory or to I/O

1980s–: ALU + control unit = CPU (central processing unit)



How the computer works

Operation

On each clock cycle, the computer fetches instructions anddata from its memory. The instructions are executed, theresults are stored, and the next instruction is fetched. Thisprocedure repeats until a halt instruction is encountered.

Four main functions• processing

• storage

• input

• output



Representing information: binary notation

• computer data (and instructions) are coded, manipulatedand stored by use of an exclusive two-state condition

• in the computer this means that "there is electricity passingthrough the circuit" or "there is no electricity passingthrough the circuit"

• represented in binary notation by the use of 1s and 0s

• copy : 10110000

• machine language: instruction set that a specific computersupports



Units

Bit

A binary digit. 0/1

Byte

8 bits. 01010101. The standard unit of measurement ofcomputer data.



Units

SI prefix Binary prefix

Name Popularvalue

SI value Name Value

kilobyte (kB) 210 103 kibibyte (KiB) 210

megabyte (MB) 220 106 mebibyte (MiB) 220

gigabyte (GB) 230 109 gibibyte (GiB) 230

terabyte (TB) 240 1012 tebibyte (TiB) 240

petabyte (PB) 250 1015 pebibyte (PiB) 250

exabyte (EB) 260 1018 exbibyte (EiB) 260

zettabyte (ZB) 270 1021 zebibyte (ZiB) 270

yottabyte (YB) 280 1024 yobibyte (YiB) 280

Table: Quantities











From Mainframes to the PC

Mainframes (Big Iron)

• RAS: reliability, availability,serviceability

• thousands of users

• multiple virtual machines

Personal computer (PC)

• for personal use

• user friendly software

• standardized, userupgradeable

Minis (workstations)

• originally in between the above two

• multi-user, multitasking

• today mostly taken over by PCs (c.f. midrange servers)



From Mainframes to the PC

Figure: IBM Z890 mainframe Figure: IBM PC

Figure: IBM iSeries server



The PC

There is no reason to suppose the average boy or girlcannot be master of a personal computer.

John W. Mauchly – 1962



The PC

Figure: An exploded view of a PC

1 display (monitor)2 motherboard3 CPU (microprocessor)4 RAM (Random Acces

Memory)5 expansion cards6 power supply7 optical disk drive8 hard disk9 keyboard10 mouse











The motherboard

Houses all basic hardware devices. Provides attachment points for theCPU, memory, storage and I/O devices (peripherals), expansion cards.

Standardised but still has many forms acc. to CPU sockets andphysical form (size and power supply).











The CPU – from 30MHz to 4–. . . GHz

FunctionInterprets instructions and processes datacontained in computer programs,executing a sequence of basic steps on aclock signal.

Architecture

The design and implementation of a CPU can vary to a large extentdepending on use. Today’s PCs predominantly use the x86 (Intel/AMD)architecture. (From 2005 the Macintosh is no longer an exception.)











Information: how fast do we need it?

Figure: Storage types w.r.t. CPU"distance"

Storage

• primary: short terminformation with quick access

• secondary: long-term storageof persistent information; usingI/O channels → slower

• off-line: storage medium canbe easily removed from thestorage device (approachesspeed of sec. storage devices)

• all long-term devices havesome standard structure tostore data in accessible format(file system → next week)











Primary storage: RAM – from 64 kB to 2–. . . GB

Figure: RAMs galore

Random Access Memory

• holds the program code anddata during computation

• all memory locations can beaccessed at almost the samespeed

• much faster than mass storagedevices (hard disk) but cannotretain data without power(volatile); more expensive

• memory wall: current memoryspeed lags behind CPUspeed. . .











Storage without power – HD

Figure: Old IBM HD

Figure: New laptop HD

Hard disk• non-volatile storage device• stores data on the magnetic surfaces

of hard disk platters

Properties

• Capacity (SI prefixed): ≤ 750GB(average PC: ≥ 100GB)

• Access/Interface type (connected tomotherboard with appropriate cable):IDE/ATA/SATA; SCSI

• Speed: rotation (10000 rpm); datatransfer (125 MB/s)

• Size: 3.5" (PC) or 2.5" (laptop)



Off-line storage – CD/DVD

Figure: CD-RW drive

Figure: DVD

Compact Disc Read-Only Memory

• non-volatile storage device, R, RW,• stores data as a series of microscopic

indentations (pits and lands, read bya laser beam)

• up to 700MiB; transfer speed up to≈7 MB/s

Digital Video Disc

• like the CD but different format,higher density

• capacity: single layer 4.7 GB, dual 8.5GB

• to be continued on week ≈12











Peripherals – Keyboard

Figure: PC keyboard

Figure: US 104 key QWERTYlayout

Computer keyboard

• device to control the operation of acomputer through pressing keys

• keys produce text (characters),actions or modify other keys (modifierkey)

Standards• several types from 83 to 130 keys• most common: PC keyboard with

QWERTY arrangement• connection to motherboard: PS/2,

USB



Peripherals – Mouse

Figure: The first mouse (1970)

Figure: Wireless mice withscroll wheel

Operation

• its motion typically translates into themotion of a pointer on a display

Types

• movement detection: mechanical("ball mouse")/optical/laser

• limbs: 1–3 buttons, scroll wheel(s)• connection: serial, PS/2, USB,

wireless











Peripherals – Display

Figure: DEC VT100 (1978)

Figure: Dual 30" Apple Cinemadisplay

Today’s dominant types, properties

• display signals generated by a computeras images on a screen

• Cathode ray tube monitors (CRT)• Liquid crystal display (LCD)• resolution: number of pixels

(160x200–1024x768–3840x2400)• size: diagonal in inches• vertical refresh rate: number of

times/sec that a display is illuminated(good CRT ≥ 85Hz)

• different standards w.r.t. resolution andcolor depth(SVGA,XGA,SXGA,SXGA+,UXGA)



Peripherals – Printer

Figure: Laser printer for home

Types

• local(ly connected): directly attachedto the PC; USB or parallel

• network printer: available through thenetwork

Technology

• dot-matrix printer: slow, poor quality, cheap, outdated• inkjet printer: slow, medium quality. BEWARE: printer is low price

but ink cartridge is very expensive.• laser printer: high quality prints, good print speed, low per-copy

cost. Printer is (was?) very expensive.











Expansion slots

Figure: Installing a PCI card

Figure: AGP graphics card

Function and standards• allow peripheral devices and cards to be

inserted and attached to the PC• ISA (Industry Standard Architecture):

outdated (black)• PCI (Peripheral Component

Interconnect): most common (white)• AGP (Accelerated Graphics Port):

high-speed channel for attaching agraphics card (brown)

Common expansion cards

• graphics card• network (ethernet) card (more on week 6)• sound, tv tuner, modem card (week 6/12)











Ports and protocols

Protocol

Communication standard (the common language) between hardwaredevices.

Ports (hardware)

Physical interface between hardware devices. (Here: PC and peripherals.)

Figure: Serial (mouse) Figure: Parallel (printer) Figure: SVGA (display)



Ports and protocols

Figure: PS/2

Figure: USB

IBM Personal System/2

• keyboard (purple), mouse (green)• not designed to be hot swappable: not to be

(dis)connected while power is on

Universal Serial Bus• allows peripherals to be connected without the

need to plug expansion cards• allows devices to be hot-swapped• becoming the (only) standard connection

method for almost all peripheral devices• Standards: 1.[01] (slow, outdated); 2.0:

high-speed• USB flash drive (128MB–2GB)











Basic Input/Output System

Figure: Bios

Function and properties

• software code run by acomputer when first poweredon

• initializes the machine so thatthe operating system (OS) canload

• coded in some non-volatilememory chip

• user customizable (for basichardware settings) but there issome read-only default forsafety











MSDOS is not dead, it just smells that way.Henry Spencer



The Operating System

Services• OS is the software which takes over the operation of the

computer from BIOS

• controls all input and output to and from the peripherals aswell as the operation of other programs

• allows the user to work with and manage files withoutknowing how the data is stored and retrieved

• manage user access to the processor and peripherals andschedule jobs (processes/programs)

• in the broad sense it contains many applications (systemsoftware) in the narrow sense it refers only to the



The Operating System

Figure: Kernel in the computer

• kernel: central part of an OS,manages the system’sresources and thecommunication betweenhardware and software

Common OSs for the PC or Macintosh• DOS: simple program loader, outdated• Windows eXPerience: dominant OS for the PC (Mac?)• Mac OS X: OS for the Mac• Linux: open source OS for PC and Mac• by default they are not compatible with each other











The boot process

PC startup

1 power on →

BIOS: checksand initializesboot devices

2 BIOS loads andexecutes the bootloader

3 boot loader loadsthe kernel

4 kernel loadsdevice drivers,starts programsto make PC readyfor user input

• keyboard• display• initial program load device: a (bootable) storage

device that contains the boot loader• boot interface is user selectable in BIOS (floppy,

HD, CD, USB drive, network)• bootable devices have a special area where the

primary boot loader resides: boot sector (in HD→ Master Boot Record/MBR)

• small program residing in the boot sector• several OSs can coexist in a PC, selectable in

the boot loader• "reverse" process: shutdown 6= switch off!!!



Summary

After this talk we know . . .• the basic building blocks of a personal computer and their

functions

• the four main operations of a computer system(processing, storage, input, output)

• what kind of software runs first after the computer ispowered on

• the role of this software i.e. how the PC starts up

• the basic functions of the operating system



Future

Next time (and after) we will explore . . .

• the Matrix . . . the virtual world of the computer

• how we can solve a lump of useful tasks (very) efficientlywith the help of the computer



Useful information

Course websitehttp://seas3.elte.hu/itcourse


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