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11 CompuServe, prestel, minitel, BTx ( Bildschirmtext)and teletex

11 CompuServe, prestel, minitel, BTx ( Bildschirmtext)and teletex

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CompuServe, prestel, minitel, BTx (Bildschirmtext) and teletex


and services emerged in the later 1970s. Equipping the customer with the terminal improved
the level of customer service which could be offered, while simultaneously reducing the
manpower required for order-taking. Since the customer was unlikely to put a second terminal
on his desk (i.e., a competitor’s terminal), it also meant reduced competition.
The travel industry rapidly reorganised its order-taking procedures to encompass the use of
computer terminals by customers. There was soon a computer terminal at every airport check-in
desk and even some large travel agents. Other travel agents, meanwhile, continued to struggle
making phone calls to overloaded customer service agent centres. For a real revolution, all the
travel agents needed a terminal and an affordable means of network access. It came with the
launch of the first dial-up information service networks, which appeared in the late 1970s and
early 1980s. The first information services were the Prestel service of the British Post Office
(BPO) and the CompuServe information service in the USA (1979). Both were spurred by
the modem developments being made at the time by the Hayes company (the Hayes 300 bit/s
modem appeared in 1977).
The Prestel service followed the invention by the BPO laboratories of a simple terminal
device incorporating a modem and a keyboard, which could be used in conjunction with a
standard TV set as a ‘computer terminal’ screen. It spurred a new round of activity in the
ITU-T modem standardisation committees — as the V.21, V.22 and V.23 modems appeared.
And it became the impetus for the new range of teletex services which were to be standardised by ITU-T. The facsimile service appeared at almost the same time and also saw rapid
growth in popularity, so that the two together — teletex and facsimile tolled the death knell
for telex — the previous form of text and data communication which had developed from the
Other public telephone companies rapidly moved to introduce their own versions of teletex. France T´el´ecom introduced the world-renowned minitel service (Figure 1.9) in 1981 and
Germany’s Deutsche Bundespost introduced Bildschirmtext (later called BtX and T-Online

Figure 1.9

France T´el´ecom’s first minitel terminal (1981) [reproduced courtesy of France T´el´ecom].


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classic). But while none of these services were truly profitable businesses, they nonetheless
were an important development towards what we today call the Worldwide Web (www). They
demonstrated that there was huge potential for greatly increased usage of the public telephone
networks for access to data information services.

1.12 The role of UNIX in the development of the Internet
In 1969, the UNIX computer operating system was developed by Ken Thompson of AT&T
Bell Laboratories. It has turned out to be one of the most powerful and widely accepted
computer operating systems for computer and telephone exchange systems requiring multitasking and multi-user capabilities. Standard UNIX commands allow for access to computer
files, programs, storage and other resources. Encouraged by the hardware volumes purchased
by AT&T (American Telegraph and Telephone company), UNIX was quickly adopted by many
computer manufacturers as their standard operating system, so that computer programs and
other applications written for UNIX could easily be ported (i.e., moved with only very few
changes) from one computer system to another.
Most importantly for the development of the Internet, one of the participants in the
ARPANET, the University of California in Berkeley, at the request of DARPA, wrote an
extension to UNIX to incorporate the newly developed TCP/IP protocols. This version of
UNIX was called UNIX 4.2BSD (Berkeley System Distribution). It was immediately used in
the ARPANET and was released to the public domain in 1983. It opened the door for rapid
further development of applications for file transfer between computers and for a more-widely
standardised form of email. The embedding of TCP/IP within UNIX also made UNIX servers
the natural choice of hardware for web servers, which would appear later.

1.13 The appearance of the PC (personal computer)
Ted Hoff at Intel invented the microprocessor in 1971. At the same time, IBM invented the
floppy disk as a convenient, small and cheap means of storing computer data. Now, using a
single processor chip, complemented by a few memory chips and input/output devices, it was
possible to create a working micro-computer. The first commercially available computer kit
(the MITS Altair) duly appeared in 1975, and the Commodore PET computer was the hit of
1977. A period of intense further development of the microprocessor chip took place at Intel.
The 8086 chip was released in 1979 and the 8088 in 1980.
Based on the Intel 8088 microprocessor, the IBM PC (personal computer) appeared in
August 1981 (Figure 1.10). This set the standard for PCs as we know them today. The IBM PC
incorporated the DOS (disk operating system) software developed by the Micro-Soft company
(later renamed Microsoft) which had been set up by Bill Gates and Paul Allen in 1975. By
1983, a new version of the IBM PC, the IBM PC XT, included a hard disk for storage of data.
Apple Computer, founded by Steve Jobs and Steve Wozniak in 1976, introduced the Macintosh computer in 1984 (Figure 1.11). It revolutionised personal computing with the graphical
user interface (GUI), the use of a mouse to ‘point and click’ and the opening of different
‘windows’ for different tasks. Microsoft quickly reacted by introducing a new operating system software, Microsoft Windows, in 1985. The ‘look and feel’ of Microsoft Windows were
so similar to the Macintosh operating system that it led Apple Computer to file a lawsuit.

1.14 Local area networks (LANs)
The PC took the business world by storm. Word processing programmes and spreadsheet
programmes made life easier for office staff, and meant that their managers could reduce the

Local area networks (LANs)

Figure 1.10

Figure 1.11


The first IBM PC (IBM 5150 : 1981) [reproduced courtesy of IBM].

The first 128k Apple Macintosh computer (1984) [reproduced courtesy of Apple Computer, Inc].


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Figure 1.12

Bus and 10baseT ‘collapsed backbone’ alternative structures for ethernet LANs.

secretarial staff. And as quickly as the use of PCs grew, so did the need for networking them
all together. Company staff wanted to be able to share data easily, and to be able to securely
store data.
The foundation stone for LANs (local area networks) was laid by the Xerox company, at
its Palo Alto Research Centre (PARC) in 1973. Robert Metcalfe and David Boggs invented
the principles of the ethernet LAN and published them in 1976. Initially ethernet was based
on coaxial cable interconnecting all the PCs together in a bus structure or backbone cable
network simply linking all the PCs together in a chain (Figure 1.12a). But as structured office
cabling based upon twisted pair cabling became popular, the most popular form of ethernet
emerged — 10baseT. Using a 10 Mbit/s adapter card in each, all the office PCs could be
connected in a star-fashion (a so-called collapsed backbone) over twisted pair cabling to the
central wiring cabinet, where a LAN hub is used to connect all the PCs together into an
ethernet LAN (Figure 1.12b).
The 3Com company introduced the first 10 Mbit/s ethernet LAN adapter card in 1981. The
official link layer and physical layer protocol standards were standardised in the renowned
IEEE 802 standards in 1982. (The link layer control (LLC) is IEEE 802.2 and the ethernet
physical layer is defined in IEEE 802.3).
Meanwhile at IBM, there was also work going on to develop the token ring LAN as specified in IEEE 802.5. This work culminated in the introduction of the 4 Mbit/s token ring LAN
in 1985 and the 16 Mbit/s version in 1988. But while some experts claimed that token ring
LAN had higher performance and reliability than equivalent ethernet LANs, token ring lost
out commercially because of its later introduction and the higher costs of the adapter cards.
Nonetheless, IBM’s work on LANs was important because of its development of NETBIOS
(network basic input/output system). NETBIOS provides a ‘layer’ of software to link a network adapter operating software to a particular PC hardware and computer operating system.
It extends the basic operating system with transport layer capabilities for inter-application
communications and data transfer.

LAN servers, bridges, gateways and routers


1.15 LAN servers, bridges, gateways and routers
With LANs came servers, bridges, gateways and routers. Initially, the servers had the primary
function of being ‘administration’ terminals for managing the LAN itself, and for being shared
file and print servers. As a file server, the server PC provided a central resource for storing,
backing-up and sharing files on behalf of PC users in the LAN. As a print server, the server
took over the job of queueing print jobs (correctly called spooling) so that a shared printer
within the LAN could print each in turn.
Initially, many servers were normal PCs, but the higher storage and greater performance
requirements of the servers quickly led to the use of much more powerful, specially developed
hardware and software. The Novell Netware software, for example, became a popular LAN
operating system — the de facto standard. It was introduced in 1983 and was hugely successful
until it was supplanted by the introduction of Microsoft’s WindowsNT in 1993.
Bridges, gateways and routers are all types of hardware which can be added into LANs
(see Figure 1.13) to provide for interconnection with other local area networks (LANs) and
wide area networks (WANs). Bridges are special telecommunications equipment introduced
into LANs to allow the LAN ‘boundary’ to be extended by connecting two separate LANs
together. A bridge, in effect, makes two separate LANs operate as if they were a single LAN.
Gateways are typically PCs within the LAN which are equipped with relevant software
and network adapter hardware to allow the LAN to be connected to an existing mainframe
computer network. The most common forms of gateways performed some kind of terminal emulation: in effect, allowing a PC within the LAN to appear to a remote mainframe
computer as if it were one of its standard terminals (so-called dumb terminal ). This allowed
the new world of PC users to replace the old world of mainframe terminal users, without
loss of their mainframe applications. The most commonly used forms of gateway and terminal emulation software were 3270-emulation (for IBM-mainframe connection of LANs) and
VT-100-emulation (for connection of LANs to DEC mainframe and minicomputers).
As the number of PCs in companies grew, so the number of LANs and LAN segments
(LAN subnetworks) grew, and it became unwieldy to operate all the individual segments as
single LAN using bridges. Instead, routers appeared. Rather than ‘flooding’ the data around
the whole LAN in an attempt to find the correct destination as bridges do, routers are more

Figure 1.13 Shared LAN devices.


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careful in keeping the amount of data to be sent to a minimum and they select carefully the
best ‘route’ to the destination from routing tables. Routers are now the most commonly used
type of equipment used in a LAN to provide ‘access’ to the Internet.

1.16 Why did IP win through as the standard for ‘open’ communication?
Internet protocol (IP) has become the predominant means of modern data communication. In
doing so, it had to fight off strong competition from alternative internationally standardised
technologies. Why did the IP protocol suite win through? Technically, because it offers a
reliable means of transmitting various different types of network as data makes its way to the
destination. But probably more important was the simple fact of its embedding into the major
computer operating systems — UNIX, WindowsNT and Windows95.

1.17 The development and documentation of IP (Internet protocol)
and the Internet
The large public data network which we know today as the Internet has its routes in the
ARPANET, the conception of which was set out in the request for proposals of summer 1968
for the original four node network. But the protocols in their current form first started to take
shape in 1974 when Vinton Cerf and Robert Kahn published the basic principles of TCP/IP.
Further important ‘landmarks’ in the history of the evolution of the Internet were the adoption
of the domain name system (DNS) in 1983, the establishment of the IETF (Internet Engineering
Task Force) in 1989 and the formal re-naming of the ARPANET AS the Internet in 1990.
The IETF is the standards body of the Internet, and the standards themselves are documented
in documents called RFCs (request for comments). The name reflects the somewhat ‘informal’
manner in which Internet standards have been evolved — by sharing ideas and documents
over the network itself. All the current standards are publicly available via the Internet at
www.rfc-editor.org. If you do refer to the standards, you may notice that many of the most
important ones were written by Jon Postel. He was the Deputy Internet Architect and RFC
editor during the 1980s and 1990s.
Following the renaming of the Internet in 1990, a number of large US-based research
and educational networks were inter-linked with the original ARPANET, with the effect of
greatly extending the network’s reach. Networks connected at this time included the US
National Research and Education Network (NREN), the US National Science Foundation
(NSF) network, the NASA (National Aeronautical and Space Administration) and the US
Department of Education network.

1.18 Electronic mail and the domain name system (DNS)
The earliest forms of electronic mail (email ) appeared around 1971. By 1972, email was
available on ARPANET. But the early forms of email were restricted to simple text messaging
between different terminal users of the same mainframe and its associated data network. It
was not until the late 1980s and early 1990s that email began to take off as a major means
of inter-company and finally, private communications. The critical developments took place
in the mid-1980s with the development of the domain name system (DNS) and SMTP (simple
mail transfer protocol). A lot of work was also undertaken under the auspices of ITU-T3 in
ITU-T stands for International Telecommunications Union — standardization sector. Until 1989, ITU-T was
previously called CCITT — International Telegraph and Telephone Consultative Committee.