The History of Computers and Networking
This lecture is divided into hyperlinked sections
The Very First Operational Computer
The End of Valve Technology for Computers
History of Communications
Before we used electricity to carry instructions along a wire there were very few methods of communication available. We could travel to the person we wanted to talk to which was direct communication; this meant that the parties that wished to share information had to meet physically. Alternatively there was indirect communication, which occurred when the originator of the message did not wish to travel to the recipient; he would ask a third party to deliver the message. For a complex message, the message would need to be written down and carried by hand (horse, boat etc.) to the recipient.
The two methods described above were only as fast as a human could travel.
Faster communication was developed to assist armed forces in their various struggles and involved visual methods such as semaphore and the heliograph. Indeed the armed forces have been instrumental in many of the projects involving communications.
Less complex but much faster methods existed
for certain
prearranged signals. Consider the Armada beacon network in southern
England
which was a set of fires placed at strategic high points, set up to
carry the
news that the Spanish fleet was about to invade England. It carried the
news to
Coded communication
· American Indian smoke signals
· Semaphore, developed for military use
· Heliograph, optical signalling using mirrors, required code – Morse good here
· Flags, as used by navy, again required code
The advent of the use of
electricity saw the proliferation of devices to transmit information,
the
earliest devices using static electricity to send a signal along a
cable. These
early ideas were not long-distance devices as the power required for
long-distance operation could not be achieved using static electricity.
In 1837 Samuel Morse
invented the first workable telegraph, applied for its patent in 1838,
and was
finally granted it in 1848. Joseph Henry helped Morse build a telegraph
relay
or repeater that allowed long distance operation. The telegraph later
helped
unite the country and eventually the world.
The advent of the use of
electricity saw the proliferation of the telegraph, using Morse code as
the
coding scheme. This involved learning a sequence of short and long
pulses to
represent the characters to be transmitted.
The telegraph soon spread as its ability to
transmit
information over great distances in a very short time became apparent.
Telegraph
wires followed the lines of railways in
Even today, the railway companies still have cabling running along the sides of the tracks, not copper wires carrying Morse messages but fibre optic cables carrying digital data. In USA the Southern Pacific Railroad operate a long distance carrier service known as Sprint (Southern Pacific Railroad International) with the cabling buried along the sides of its tracks.
Later in the 19th Century,
scientists were
working on microphone and loudspeaker devices that would lead to the
invention
of the telephone by Alexander Graham Bell in 1876, in
The telephone was able to use the same cabling as had been used for Morse but the use of speech instead of code allowed anybody who could afford a telephone to communicate.
The copper cabling used over 100 years ago for telephony is very little different to the subscriber loop entering our homes today.
The Birth of the Computer
In 1791, an Englishman known as Charles Babbage was born. He was responsible for the design of the very first forerunner to our modern day computer. This was a mechanical device that contained cogs and wheels. His machine contained an input device, a data store, an arithmetic unit, a control unit and an output display device.
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In 1822, Babbage proposed building a machine called the Difference Engine to automatically calculate mathematical tables. The Difference Engine was only partially completed when Babbage conceived the idea of another, more sophisticated machine called an Analytical Engine. (Some texts refer to this machine as an "Analytical Steam Engine," because Babbage intended that it would be powered by steam). |
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The Analytical Engine was intended to use loops of Jacquard's punched cards to control an automatic calculator, which could make decisions based on the results of previous computations. This machine was also intended to employ several features subsequently used in modern computers, including sequential control, branching, and looping. |
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Working with Babbage was Augusta Ada Lovelace, the
daughter of the English poet Lord Byron. Had the Analytical Engine ever actually worked, |
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Babbage worked on his Analytical Engine from around 1830 until he died, but sadly it was never completed. |
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Below can be seen a schematic of his machine which bears very close resemblance to the schematic of a modern-day computer. The mill is now termed the CPU (Central Processing Unit).
Although never realised in hardware, his machine was to form the basis of today’s computers.
A Frenchman, Boole developed Boolean algebra in 1845 that is now used for describing relay and switching circuits and logic gate operations.
The Beginnings of Memory
An American named Hollerith introduced the punched card to be used in collating the 1890 United States census. Punched cards and paper tape were used in the latter part of the 19th century to operate looms, pianos etc. In 1896 Hollerith formed his own company, the Tabulating Machine Company which he sold in 1911. It merged with two other companies and by 1924 became the International Business Machine Corporation, better known as IBM.
Paper tape was also used to store information, commonly 8 channels with a row of sprocket holes to move the paper. Today cash registers still record output on paper tape.
In 1937, Howard A Aitken of Harvard USA, using existing punched card technology, started work with the International Business Machines Corporation, (IBM) to produce a machine to solve differential equations.
In 1939, the 2nd World War began and the armed forces realised that an automated system for performing repetitive tasks could be useful. During wartime, research on projects that will bring an advantage in the struggle always increases and coupled with the money that can be thrown at the problem always brings technological advances.
The Very First Operational Computer
One problem that existed in the UK during the 2nd World War was that Army Intelligence required the facility to crack enemy codes. At Bletchley Park in southern England, a secret intelligence unit was set up to decipher the German Lorenz cipher that had been created using the Enigma machine. It was at Bletchley Park that the first operational computer in the world, Colossus, was built by a British telephone engineer, Tommy Flowers. This computer had the processing power of a Pentium 2 in the 1940s! After the war, the British government, paranoid that another country would discover that it had a machine capable of cracking ‘secret’ codes, ordered the entire computer and all its documentation to be removed and destroyed. The machine has been rebuilt using the scraps of documents and a single remaining photograph and can be seen running today in the National Museum of Computing.
A more mundane problem for the army and navy was the calculation of angles of gun elevations so that Ordnance could aim their shells accurately. Many man-hours had previously been taken up in the tedious manual calculations required to calculate such tables.
In 1942 Ballistic Research Laboratories in the United States began working on just such a system to produce ballistic tables. On 15 Feb 1946 ENIAC (Electronic Numerical Integrator and Calculator) was inaugurated. This used vacuum tubes (valves) so had no moving parts. ENIAC could do in 1 hour what the Harvard MK1 took one week. Addition took 200 msec, multiplication 2800 msec.
By 1944 Howard Aitken’s machine, the Harvard MK 1 had begun work on classified topics for the US navy. The Harvard MK 1 was 16m long, 2.5m high, and had 3/4 million parts connected by 800 kilometres of wire.
EDVAC (Electronic Discrete Variable Automatic Computer ) was built according to the ideas of Dr John von Neumann in his paper "Theory and Techniques of Electronic Digital Computers". As a consultant to ENIAC he first proposed the concept of the stored program that could be held in memory and manipulated in much the same way as data. This had acoustic delay lines consisting of tanks of mercury, the pulses representing data circulated until required. Instructions and data were held in the memory unit. The project floundered when the designers left to form their own computer manufacturing company, there being engineering difficulties during development, so EDVAC was not the first practical computer to operate with internally stored program. This accolade fell to British EDSAC (Electronic Delay Storage Electronic Calculator).
The EDSAC was the world's first
stored-program computer to
operate a regular computing service. Designed and built at
The EDSAC was a binary computer and used tanks filled with mercury working on an ultrasonic principle for storage. The main store consisted of 32 mercury-filled tanks, each of which was about 5 ft long and held 32 numbers of 17 binary digits, one being a sign digit. This gave 1024 storage locations in all. It was possible to run two adjacent storage locations together in order that it could accommodate a number with 35 binary digits (including a sign digit). This meant that at any time the store could contain a mixture of long and short numbers. Short tanks that could hold one number only were used for accumulator and multiplier registers in the arithmetical unit, and for control purposes in various parts of the machine.
EDSAC
pictured shortly after completion in 1949
EDSAC’s statistics
- 650 instructions per second.
- 1024 17-bit words of memory in mercury ultrasonic delay lines.
- Paper tape input and teleprinter output at 6 2/3 characters per second.
- 3000 valves, 12 kW power consumption, occupied a room 5m by 4m.
- "Operating system" occupied 31 words of read-only memory.
- Early use to solve problems in meteorology, genetics and X-ray crystallography.
- First book on programming by Wilkes, Wheeler and Gill published in 1951.
- Magnetic tape backing store added in 1952 (but never worked really well).
- First course in Computer Science started in 1953, using the EDSAC.
The Manchester MK1 was inaugurated in June 1948 and held 32 x 31-bit words to store data, instructions and intermediate results and it tested the principle of Williams-tube type electrostatic storage.
The 2nd generation of computers used magnetic
drum or
magnetic core memory, which became available around 1952. They were
compact,
reliable and faster. Six years later IBM marketed the IBM 605 magnetic
memory
which sold 1000 units.
A timeline of important steps in the
history of computing can be read here.
The End of Valve Technology for Computers
The early computers used valves to perform their switching and because of the unreliability of valves coupled with the huge number used in a computer, it was not unusual for a valve to malfunction during the running of a program. This meant that technicians armed with boxes of spare valves had to be on hand whenever the computer was operational.
The Philco Corporation developed their transistor in 1954 and so by 1958 valves were becoming increasingly obsolete for switching applications (although they still to this day remain dominant for high-power applications). The transistor is a solid-state amplification and switching device with a long life, whose introduction made high-speed compact and reliable machines possible.
Mainframe Computers
From the early 1960's
onwards in military, governmental and educational establishments,
computers
were built and used for research purposes. These were the large
computers known as mainframes that filled great rooms and had much
computing
power. It was from mainframes that small
computer networks began to evolve
The mainframe was connected to many non-intelligent terminals (slave units) in a multi-drop configuration. The terminals could communicate with the mainframe (host) but not with each other.
The slave units could be
any type of terminal which required to send or receive data from the
Master unit,
which in this case was a mainframe computer.
Clearly there had to be
a protocol or set of rules for sending data because only one unit could
use the
transmission path at one time otherwise messages would become mixed and
thus
garbled. The protocol was known as the Normal Response Mode and was
under the
control of the Master unit (mainframe).
When the slave units began to have more intelligence and the units began to be terminals controlled by humans for inputting data, more flexible arrangements became necessary and this saw the advent of store and forward systems in the form of packet and message switching.
Integrated Circuitry
Towards the end of the 1960s, Integrated Circuitry began to replace the discrete components that had been used for the previous ten years. A technique known as Small Scale Integration (SSI) was able to combine around 10 discrete components (transistors, diodes & resistors) onto around 5mm square of silicon substrate.
Development of SSI led to Medium Scale Integration (MSI), then Large Scale Integration (LSI) with many thousands of components in the same area of silicon.
Very Large Scale Integration (VLSI) provided the means to implement around 1 million components per chip.
VLSI led to 4th generation computers and the microcomputer.
Current technology can produce silicon wafers with around 2.3 billion components per chip as in the 8-Core Xeon Nehalem-EX.
The Microcomputer
During the 1970s various companies began to investigate and produce single-chip microprocessors and by the beginning of the 1980s IBM had put into production its XT and AT series of microcomputers (PCs). These were very expensive when compared to today’s powerful Pentium desktop machines but they were the beginnings of the desktop computers we use today.
Businesses were slow to adopt these machines at first because of a lack of useful applications, but in the early 1980s Lotus introduced their Notes suite of programs. This provided industry with the first set of business tools for automating every-day office tasks such as word processing and spreadsheet calculations and database creation.
This was to provide the much-needed boost
that the computer
industry required. By making the IBM machines ‘open systems’ the
specifications
for the machines were freely published and other companies were free to
produce
clones of the original AT and XT machines. The proliferation of the
desktop PC
was to continue exponentially from then onwards. The volume of sales
made the
PCs drop in price in real terms so that today, a machine that is
Internet ready
and equipped with Ethernet and Wireless adapters is available for less
than
£300.
The desktop PCs days may well be numbered with the release of small laptops, the iPad and mobile phones that are microcomputers. These lightweight clients rely on data centres and cloud computing for their operation.
The Start of Networking
During the latter half of the 1960s, experiments were conducted in an attempt to connect mainframe computers together. This was the Arpanet (Advanced Research Projects Agency Network), an American project to experiment with packet switching of data.
By summer of 1969 the Arpanet was operational with four interconnected nodes. This managed to connect a few host computers and terminals. The funding came from the American Department of Defence (DoD). Arpanet was to become a test bed for packet-switching technology and the protocols that were to be used for cooperative, distributed computing.
The main idea behind the network was to provide a robust communication system for the military that would still be able to function even if large sections were to fail. The reasoning was that America was waging a Cold War against Russia at the time and America wanted a communication system that would still function in the case of a nuclear strike. The rules of communication (protocols) were deliberately designed so that the information travelling on the network would be able to find its destination provided at least one path existed.
The Internet had its own trial by fire during the terrorist attacks on New York and Washington in 2001, and apart from light congestion it stayed up. If you want to see the actual stats of how the Internet survived, check this site: http://www.w2knews.com/rd/rd.cfm?id=091301-NetTraffic
The packet-switching technology was so successful that ARPA was able to apply the same switching techniques to both Packet Radio and satellite communications, SATNET. These three communication environments used widely differing values for parameters such as packet size and bit ordering so it was a big task to integrate these networks.
Some of the early applications that were developed using Arpanet were TELNET and FTP (File Transfer Protocol). TELNET provided a common interface for remote computer terminals and it allowed any computer terminal to communicate with any remote host. Software was written for each type of computer that supported the TELNET terminal. Now any type of terminal could interact with any of the computers within the network.
FTP allowed the transparent (i.e. seamless) transfer of files from one computer to another via the Arpanet. Early links between the nodes were low speed, being around 50 Kbits/sec. FTP managed to negotiate the different word sizes, orders of bit storage and character formats that the different computers were using.
Even today, TELNET and FTP are still being used widely.
Hardware was expensive
in the 1980s and not every PC would have a printer. If you didn't have
a
printer attached to your PC you would have to copy the file to a 5-¼
inch
floppy disk and walk to a PC that had a printer. Because of the walking
involved, this became light-heartedly known as Sneakernet.
File sharing became a
problem and also management of the many separate PCs became a
nightmare. The
solution was to link the computers together somehow and thus small
networks
were born. It was Xerox who introduced the Ethernet networking system
and the
Local Area Network (LAN) was born. As these networks grew in number it
became
apparent that it would be necessary to link these small local networks
together
and so wide area networking became a reality, using the cables provided
by
telecommunications companies to link the smaller networks together.
Most networking today is
accomplished using WiFi which allows networks to be setup very easily
without the need for a wired infrastructure.
Electronic mail (email) was invented in 1972. This was the first package that was able to provide a distributed mail service across a network of computers.
By 1973, 75% of all Arpanet traffic was email. Because of its usefulness, Arpanet attracted even more users and so more nodes had to be added to the network along with higher speed links.
The growth of Arpanet brought in more users other than the academics and research personnel who had been the main users up to this time. DoD personnel who had a non-military job to perform within DoD started to use the system. With this growth of the network came the necessity for proper network configuration and management. Other important issues were the reliability and availability of the network.
In 1975 the Arpanet was transferred from the research-funding agency ARPA to the Defence Communications Agency.
TCP and IP
In May of 1974, Vint Cerf and Bob Kahn of
ARPA began to
develop methods and protocols for internetworking. This is the ability
to
communicate across different and arbitrary packet switched networks.
The
proposal in their paper was enthusiastically received and their
proposal was
refined and with contributions from ARPANET and
This provided the underpinning of what was to become the Internet as we know it today with Arpanet being just one of a collection of interconnected networks.
Between 1982 and 1983, Arpanet converted form its original NCP (Network Control Protocol) to TCP/IP. Many networks throughout the world were interconnected using this technology.
Worldwide realisation of the usefulness of
the technology of
networking brought the National Science Foundation (NSF) to give
support to
other computer science research groups. In 1986, NSF extended support
for all
disciplines of the general research community with the NSFNET backbone.
Eventually NSFNET offered interconnection via its backbone to regional
packet
switched networks across the
In 1990 the ARPANET was shut down.
OSI Model
THE ORIGINS OF
OSI
William Stallings
The history of the development of
the OSI
model is, for some reason, a little-known story. Much of the work on
the design
of OSI was actually done by a group at Honeywell Information Systems,
headed by
Mike Canepa, with Charlie Bachman as the principal technical member.
This group
was chartered, within Honeywell, with advanced product planning and
with the
design and development of prototype systems.
In the early and middle '70s, the interest of Canepa's group was
primarily on
database design and then on distributed database design. By the
mid-70s, it
become clear that to support database machines, distributed access, and
the
like, a structured distributed communications architecture would be
required.
The group studied some of the existing solutions, including IBM's
system
network architecture (SNA), the work on protocols being done for
ARPANET, and
some of the concepts of presentation services being developed for
standardized
database systems. The result of this effort was the development by 1977
of a
seven-layer architecture known internally as the distributed systems
architecture (DSA).
Meanwhile, in 1977 the British Standards Institute proposed to the
International Organization for Standardization (ISO) that a standard
architecture was needed to define the communications infrastructure for
distributed processing. As a result of this proposal, ISO formed a
subcommittee
on Open Systems Interconnection (Technical Committee 97, Subcommittee
16). The
American National Standards Institute (ANSI) was charged to develop
proposals
in advance of the first formal meeting of the subcommittee.
Bachman and Canepa participated in these early ANSI meetings and
presented
their seven-layer model. This model was chosen as the only proposal to
be
submitted to the ISO subcommittee. When the ISO group met in
Copyright 1998
WilliamStallings.com/Extras/OSI.html
The World Wide Web
During Spring of 1989, Tim Berners-Lee
working at CERN
(European
Organization
for
Nuclear Research) proposed
the idea of a distributed hypermedia technology to facilitate the
sharing of scientific papers among academic centres. In 1991 he
released a working browser to colleagues at CERN.
His idea was taken up by scientists and
entrepreneurs alike
and produced what we know today as the World Wide Web. The pages of
html reside
upon thousands of web servers and billions of pages are available to be
viewed
from any PC connected to the Internet. Read an article on the
history of browsers.
The cheapness of personal computers has led
to around 60% of
all
In the last 19 years we have seen the humble beginnings of sharing scientific intelligence accelerate rapidly to the highly connected web world we know today with social communication applications such as Facebook and Twitter being commonplace and e-commerce rapidly replacing analogue methods of business.
Conclusion
Communications have been constantly improving
globally with military
means being the prime source of income and research. Times of conflict
have
brought the major advances in communications and computer technology.A
major field of investment today is in network security to help prevent
digital warfare.
Once the military have produced a particular
product,
a less robust
version is handed down to the public for their use. The price of
hardware is
constantly dropping, in line with Moore's Law, as production runs
increase and demand for a product grows.
Communications will increase in number and complexity as the years
advance.