1. Postacademic Interuniversity Course in Information Technology – Module C1p1 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 ?

2. Postacademic Interuniversity Course in Information Technology – Module C1p2 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

3. Postacademic Interuniversity Course in Information Technology – Module C1p3 Music Records Analog Digital (CD) (44100 measurements/s) -096 +057 +164 +210 +219 +216 +165 -003 -117 -183 -138 -067

4. Postacademic Interuniversity Course in Information Technology – Module C1p4 Records with a scratch Analog Digital (CD) -096 +057 +164 +210 XXXX -117 -183 -138 -067 +210 +145 +079 +014 -052 -117

5. Postacademic Interuniversity Course in Information Technology – Module C1p5 Remote Computers Access (1970) Star Network Mainframe Computer Dumb Terminals

6. Postacademic Interuniversity Course in Information Technology – Module C1p6 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

7. Postacademic Interuniversity Course in Information Technology – Module C1p7 Local Area Networks (1970) LAN’s initially introduced for Printer sharing File sharing...

8. Postacademic Interuniversity Course in Information Technology – Module C1p8 The Dual Screen Desk (1980) WAN LAN

9. Postacademic Interuniversity Course in Information Technology – Module C1p9 LAN-WAN Integration (1990) WAN LAN

10. Postacademic Interuniversity Course in Information Technology – Module C1p10 Client - Server Systems Interconnection Network (LANs+WAN)

11. Postacademic Interuniversity Course in Information Technology – Module C1p11 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

12. Postacademic Interuniversity Course in Information Technology – Module C1p12 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 !!!

13. Postacademic Interuniversity Course in Information Technology – Module C1p13 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