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The 19th century telecommunications Telegraph - Telephone Digital vs. analog communications The voice networks & the data networks The electronics revolution (1960-1980) Digital sound Mainframe computers with remote access The first unification : ISDN Local area networks

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Presentation Transcript
contents
The 19th century telecommunications

Telegraph - Telephone

Digital vs. analog communications

The voice networks & the data networks

The electronics revolution (1960-1980)

Digital sound

Mainframe computers with remote access

The first unification : ISDN

Local area networks

Wide area and local area networks integration

The Internet

The research project

The universal computer communications medium

The successful unification ?

Contents
the electronics revolution 1970 1980
Integrated circuits (“chips”) make electronics affordable.

Mainframe computers become very powerful

Mini & microcomputers become very popular

Digital techniques offer better price/performance for sound applications

The Electronics Revolution(1970-1980)
music records
Music Records

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Digital (CD)

(44100 measurements/s)

Analog

records with a scratch
Records with a scratch

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Analog

Digital (CD)

i s d n the first attempt to integrate voice and data
Integrated Services Digital Network

Voice digitized at 64 Kb/s (8000 samples/s, 8 bit)

Truly digital signaling

A telephone connection = a 64 Kb/s digital link

A 64 Kb/s digital link is excellent for connecting a terminal to a mainframe computer

Connection time billing inadequate for data

ISDN widely used for telephony

ISDN marginal for data applications

I S D NThe first attempt to integrate voice and data
local area networks 1970
Local Area Networks(1970)
  • LAN’s initially introduced for
    • Printer sharing
    • File sharing
    • ...
client server systems
Client - Server Systems

Interconnection Network (LANs+WAN)

client server systems benefits
Sharing of storage

Access to common data

Professional back-up facilities

Centralized software (& data) maintenance

Sharing of processing power

Unloading of central servers

Supporting local clients for exceptional needs

Sharing of expensive peripherals

Client - Server SystemsBenefits
terminal emulation sub minimal client server system
The personal workstations are used

as stand alone computers

as terminals connected to other computers

The user has to mentally switch between widely different user interfaces and operating systems.

Transferring data between local and remote applications is far from trivial

Terminal emulation is very user unfriendly !!!

Terminal Emulation= sub-minimal Client-server system
virtual mainframe true client server system
The users interface of all applications runs on the personal workstations.

For some applications, the workstation requests help from specialized servers. The user remains unaware of such requests.

Servers can be optimized for specific tasks

Virtual Mainframes can be

Very user friendly

cost effective

Virtual Mainframe= true Client-Server system
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