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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The 19th century telecommunications
Telegraph - Telephone
Digital vs. analog communications
The voice networks & the data networks
The electronics revolution (1960-1980)
Mainframe computers with remote access
The first unification : ISDN
Local area networks
Wide area and local area networks integration
The research project
The universal computer communications medium
The successful unification ?
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
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
Interconnection Network (LANs+WAN)
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
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 !!!
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