Lecture 1

Computer & Network Technology

Chamila FernandoBSc(Eng) Hons,MBA,MIEEE

Lecture 1: Introduction

Overview

History of Computers

Application Areas

Types of Computers

Computer Configurations

Computers as Information Processors

Lecture 1: Introduction 2

Lecture 1: Introduction

Basic Machine Hardware Architecture CPU Memory/Storage Main Memory Input/Output Devices

Basic Machine Software Flowcharts Languages Operating Systems System Utilities Applications

What’s in Computer & Network Technology..?Lecture 1: Introduction 3

Overview of Part 1

Number system:Number system: how is information represented in a computer.

Boolean Algebra:Boolean Algebra: the basis for logic design and manipulation of information.

Logic gates:Logic gates: what are the gates used, and how circuits can be made from gates.

Function simplification:Function simplification: to reduce the size of design, increase speed, etc.


Overview of Part 1

Combinational circuits:Combinational circuits: simple circuit design without memory.

Sequential circuits:Sequential circuits: circuit design with memory. Disk:Disk: storage techniques. Bus:Bus: internal communication. I/O:I/O: devices, technology, etc.



AbacusAbacus invented in Babylonia in 3000BC

Adding machine by Blaise Pascal (1642)

Difference engine and the analytical engine by Charles Babbage (1842)

IBM first electromechanical computer (using relays) designed by Howard Aiken (1937) was based on punched cards. used to calculate tables of mathematical functions


http://www.comp.nus.edu.sg/~sf100/c1p7p2.htm




History of Computers 1st Generation Computers (1940s to early 1950s) – based

on vacuum tubesvacuum tubes technology. 1943 – ENIAC: first fully electronic computer, designed by John

Mauchly 1944 – Mark I: Howard Aiken 1946 – EDVAC: first stored program computers, designed by John

von Neumann

2nd Generation Computers (late 50s to early 60s) – based on transistorstransistors technology. more reliable, less expensive, low heat dissipation IBM 7000 series, DEC PDP-1



3rd Generation Computers (late 60s to early 80s) – integrated circuitsintegrated circuits (IC). IBM 360 series, DEC PDP-8 IC – many transistors packed into single container

low prices, high packing density

4th Generation Computers (present day) LSI/VLSI small size, low-cost, large memory, ultra-fast PCs to

supercomputers

5th Generation Computers (future) massively parallel, large knowledge bases, intelligent Japan, Europe and US advanced research programs



Web sites History of Computers

(http://www.comp.nus.edu.sg/~sf100/c1f7.htm) ACM Timeline of Computing History

(http://www.computer.org/computer/timeline) The Virtual Museum of Computing

(http://www.comlab.ox.ac.uk/archive/other/museums/computing.html)

IEEE Annals of the History of Computing (http://www.computer.org/annals/)

and others (surf the web)


Application Areas

Scientific:Scientific: weather forecasting, simulation, space-program. one of the earliest application areas. heavy computation but small amount of data.

Commercial:Commercial: accounting, banking, inventory, sales. changes nature of business – information is money. high data throughput, simple calculations.

Manufacturing:Manufacturing: numerical control, CAD/CAM, integration. graphics, interfacing, device-drivers, networks.


Application Areas

Real-time & Control System:Real-time & Control System: air-traffic control, aircraft,nuclear power station. real time, very fast, safety-critical.

Educational & RecreationalEducational & Recreational CAI software, multi-media, games, Internet, World Wide Web.

TelecommunicationTelecommunication Network, SCV, Singapore One.


Types of Computers

Supercomputers:Supercomputers: very fast (Gflops) but expensive machine($10m), vector or parallel

processors, used in scientific applications and simulations.

Mainframes:Mainframes: fast (>10mips) but expensive ($1m), high-throughput, used in

large commercial organisations, support many concurrent users interactively.

Mini-computers:Mini-computers: fast but affordable ($200k), used in medium-sized organisations

(e.g. SoC), support multiple users.


Types of Computers

Workstations:Workstations: affordable ($20k) and fast single-user systems (20 riscs mips),

good graphics capabilities, engineering, network-based computing.

Micro/Personal/Home Computers:Micro/Personal/Home Computers: cheap and affordable ($3k), transportable, home use, good for

games and as educational tool, word processing, suitable for small enterprise.


Computer Configurations Stand-alone computer systemStand-alone computer system

Modem connectionModem connection



Terminals-host connectionsTerminals-host connections



Network of computersNetwork of computers




Example: An automobile augments our power of locomotion.

A computer is a device capable of solving problems according to designed program. It simply augments our power of storage and speed of calculation.

Driver

Programmer


Unlike previous inventions, computers are special because they are general-purposegeneral-purpose. Could be used to perform a variety of tasks.

Computer = Hardware + SoftwareHardware + Software. Hardware: physical components for computation/processing;

should be simple, fast, reliable. Software: set of instructions to perform tasks to specifications;

should be flexible, user-friendly, sophisticated.


Computer as Information Processors


Computer are Information Processors

Data Units: 1 bit (binary digit): one of two values (0 or 1) 1 byte: 8-bits 1 word: 1, 2, or 4 bytes, or more (depends on ALU)

Computer system

Raw data

Processed information

Basic Machine Hardware Architecture

Main Components: CPUCPU (Central Processing Unit: controls devices and processes

data). MemoryMemory: stores programs and intermediate data. Input DevicesInput Devices: accept data from outside world. Output DevicesOutput Devices: presents data to the outside world.

An analogy with Human Information Processors: CPU – brain’s reasoning powers Memory – brain’s memory Input Devices – eyes, ears, sensory sub-system Output Devices – mouth, hands, facial and body expressions




Monitor (Output)

Mouse and Keyboard (Input)

Headphone (Output)

Hardware box (contains processor, memory, buses etc.)



Motherboard (Printed Circuit Board)

Processor

Slots for RAM chips

Network card and CRT card

Cage for mounting drives

Floppy disk drive and Hard disk drive

© above picture: Patterson and Hennessy

Hardware – CPU

CPU = control unit + ALU + registers

Control Unit :Control Unit : monitors and directs sequences of instructions

Execution CycleExecution Cycle (repeated): fetch (next instruction) decode execute


Hardware – CPU

ALU:ALU: performs simple arithmetic and logical operations. Examples: Add, subtract, and, or, invert, increment etc.


A B

ALUselect

R = A op B

n-bits operations

R

Hardware – CPU

Registers:Registers: temporary results + status information ACC (accumulator) – current data PC (program counter) – points to next instruction IR (instruction register) – current instruction MA (memory address) – address to read/write MB (memory buffer) – data to read/write


Hardware – Memory/Storage

Purpose: to store program and data.

Desirable Traits: fast access, large capacity, economical, non-volatile.

However, most memory devices do not have all these traits.


Hardware – Memory/Storage

Solution: hierarchical combination


registers

main memory

disk storage

magnetic tapes

Fast, expensive (small numbers), volatile

Slow, cheap (large numbers), non-volatile

Hardware – Main Memory

Fast BUT volatile (need power to maintain data)

Logical structure – table of memory cells/units.


0123

2m-32m-22m-1

addresses

memory cells

8 bits or more

MAR

MBR

address

data

Hardware – Main Memory

Memory cells may be grouped into pagespages (say 512 consecutive words per page).

Units 1 KBytes = 1024 (or 210) bytes 1 MBytes = 1024 Kbytes (or 220 bytes) 1 GBytes = 1024 Mbytes (or 230 bytes)


Hardware – Input/Output Devices

Input devicesInput devices: read/accept data (into computer) obsolete: card reader, paper tape reader present: keyboard, mouse, light-pen, optical char reader future: voice and vision recognition.

Output devicesOutput devices: write/display data (to users) obsolete: card & paper punch, teletype present: VDU (visual display unit), printers, plotters, graphics

display, sound future: voice synthesis.


Basic Machine Software

SoftwareSoftware is the key to making computers general purpose.

Software are often built hierarchically, with layers of software providing successive higher-level of abstractions.

This structure is reflected by the following onion layer view of software.


Basic Machine Software


HardwareOperating system

System utilities

Applications/User programs

Software – Flowcharts The sequence of instructions of a software/program can

be graphically specified using flowchartsflowcharts.

The flowchart technique maybe a little outdated but could still be used in a clear manner for simple problems.

As an example, the procedure to find the roots of a quadratic equation, ax2 + bx + c = 0, can be written using the following equation:


aacbbroots 2/)4( 2

Software – Flowcharts This procedure can be coded in the following flowchart:


aacbbroots 2/)4( 2

Read a,b,c

a=0?

d:=b2 - 4ac

d>0d=0d<0

Writereal root

Writecomplex roots

Writereal roots

= <

>

no

yes Writenot quadratic

Software – Languages

All programs will have to be coded in some programming language – usually text-based.

The native language of machine is called machine machine languagelanguage.

This consists of a set of primitive instructions, coded in numbers.

An example is "0310 0412 0512". But can you understand what it does?



Possible to use more human-readable mnemonic instructions.

These are know as assembly languageassembly language instructions.

Normally, assembly language has a 1-to-1 correspondence with machine language.


Mnemonic Description

ADD 10 AC:=AC+C(10)

SUB 12 AC:=AC-C(12)

STO 12 C(12)=AC


Assembly language is still very primitive.

Higher-level LanguagesHigher-level Languages, like Pascal, C, Fortran, which are a little closer to English language have been developed.



An example Pascal program to find roots of quadratic equation:


read(a,b,c);if a=0 then writeln ("not a quadratic equation") else begin d := sqr(b)-4*a*c; if d>0 then writeln ("complex roots") else if d=0 then writeln("single root =",-b/(2*a)) else writeln ("root1=",-b+sqrt(d)/(2*a), "root2=", -b-sqrt(d)/(2*a)); end;

Software – Operating Systems

Operating SystemOperating System (OS) is situated directly above hardware. It controls and manages the available hardware resources.

Often, OS has special access privileges to certain categories of instructions and certain hardware

User programs have to go through OS for these privileges.


Software – Operating Systems

Associated Functions/Tasks: boots up machine loads user program allocates main memory/storage space schedules concurrent user programs drivers to service various devices (terminals, printers, etc.)


Software – System Utilities

Above the OS, there is a set of frequently executed programs,called System UtilitiesSystem Utilities. These utilities are often packaged with OS. Used by programmers/analyst to help develop applications.

Some examples Editor: compose/edit user programs or data files Assembler: translates assembly to machine code Compiler: translates high-level language to assembler/machine

code Spooler: temporary stores print files for queuing


Software – System Utilities

Some examples (continued) Mailer: forwards/receives mails between users DBMS (Data-Base Management System): centralised

management of data at a more abstract level than files Window Management System: multiple windows can appear on

single screen. These together with various graphical entities (e.g. menus,panels, buttons) can be managed by WMS.


Software – Applications

Word-ProcessorsWord-Processors: compose/edit reports/articles

Accounting PackageAccounting Package: keeps track of accounting transactions, produces daily/weekly/monthly (profit/loss) reports

Inventory SystemInventory System: keeps track of stock levels

Personnel/Payroll SystemPersonnel/Payroll System: staff records, monthly salary

CS1104-1 Lecture 1: Introduction 43

What’s in Computer & Network Technology..?

CS1104-1 Lecture 1: Introduction 44

I/O systemProcessor

Compiler

OperatingSystem

(Windows XP)Instruction Set Architecture

Datapath & Control

Memory

Software

Assembler

Computer Architecture

Application (Netscape)

Digital Designtransistors

HardwareDigital Logic Design

Thank youThank you


Lecture 1

Education

software system

computer amp

dec pdp

network technology

devices obsolete

software flowcharts

software

devices