Introduction to Computing and the Internet

CIS 110

http://homepages.gold.ac.uk/spiegel/supervisions.htm

The course organisation is based on the University of London study guide “Introduction to Computing and the Internet”, published by Francis Lin (2004).

Useful textbooks:Stallings, W. (2003). Computer Organization and

Architecture: Designing for Performance. Upper Saddle River, N.J.: Prentice-Hall.

White, R. (2002). How Computers Work. 6th Edition. Indianapolis: QUE.

Useful Lab exercise:

Adrian Passow’s html tutorial which is available at:

http://doc.gold.ac.uk/~ma901ajp/HtmlLab/

1st Module: General Introduction:

Binary numbers: 01101000101010…Bits, bytes, kilobytes, megabytes…1 bit = either a zero or a one, e.g. 0 or 11 byte= 8 bits, e.g. 011011011 Kilo = 1000 (but 1 kilo byte = 8 bits *

1024)1 Mega = 1 million1 Giga = 1 billion1 Tera = 1 trillion

Most computers consist of…

Input/output devices: keyboard, mouseVisual display units: screenGraphical user interfaces: display on the screen that allows you to interact, e.g. by pointing, clicking, dragging. Objects that you see on screen, e.g. wastebasket, folders, symbols such as disk, scissors, etc.CPU: processor

Most computers consist of…

Hard-driveRAMCards, such as graphics cards, sound cards, ethernet cardsOperating systems, e.g. UNIX, Linux, Windows, MacOSProgrammes (written in assembly language, Java, C, C++, Visual Basic, Python, Perl etc.)

History: 4 Major Developments

Batch Systems: 1950s to early 60s. Use of technology was isolated from actual work and processed at different times (e.g. copying financial/bookkeeping activities from forms into the system).Online Systems: From mid 60s onwards. As the name suggests, activities can be processed in real time (e.g. updating account details).

PCs: From early 80s onwards. PCs allow individual users to develop systems that are specialised to their own work, and to be mobile, e.g. work from home. Examples that have brought advances are relational databases, spreadsheets, word processing, etc. Traditionally, however, PCs were isolated from organisational systems.Networked Systems: From late 80s onwards. Networked systems have the advantage of connecting different individual systems into one coherent system, e.g. by making use of servers, letting people log in from their homes.

Prior to modern developments:1. The abacus (rows and columns that allow a skilled

person to deal with addition, subtraction, multiplication and division).

2. Pascal’s and Leibniz’ computation machines: several wheels that all carry 10 segments and the position of each wheel represents a number (0-9) plus a carry-over lever. The arrangements of the wheels allowed the machine to calculate a sum and to present this sum through the particular position of the wheels. Leibniz built a similar machine with wheels that could do multiplication and division as well.

3. Babbage’s difference engine could compute tables of numbers for naval navigation, e.g. x2 for any value of x. This machine punched the result into a copper plate. It already processed simple algorithms and had input/output devices as well as a mill as the processing unit.

Prior to modern developments:4. ENIAC: whilst Babbage’s difference engine was made

of cogs, wheels and gears, ENIAC (Electronic Numerical Integrator and Computer) used vacuum tubes for number computation. The switches between the vacuum tubes were able to represent 2 states: ON and OFF (much like modern computers have switches). Programming was done manually though.

5. Von Neumann machine: The first machine that could perform all operations electronically and did not need any manual switching between states. It consisted of a Central Processing Unit, Memory as well as Input/Output devices. These were connected through a System Bus, which is a set of wires. The majority of present computing architectures have this structure. John von Neumann invented it in 1943 at the Institute for Advanced Studies in Princeton, NJ.

Prior to modern developments:6. The ISA Computer and the binary system

John von Neumann’s architecture was also referred to as ISA machine. The ISA used vacuum tubes that were based on a binary system. Whilst binary arithmetic and calculus were introduced by Leibniz or Newton in the late 17th Century (there is an ongoing debate between historians who was first), the first machine based on the binary system was developed by Zuse in 1938 (this machine was entirely mechanical though and did not have the von Neumann architecture yet).

The binary system was favoured over the decimal system because transistors were invented in 1947 (at the Bell labs). Transistors are small semi-conductor devices that have 2 states: open or closed, hence they were suitable to represent binary numbers.

Technical aspects of computers since the

1940s

1st generation (1943-59): Bulky machines using relays and vacuum tubes.2nd generation (1959-65): Transistor-based machines with magnetic core memory, programmed with high level languages (e.g. Fortran or Cobol).3rd generation (1965-75): Integrated circuits. Operating systems permitting shared use of machines.

Technical aspects of computers since the

1940s

4th generation (1975-85): Machines built with large-scale and very large-scale integrated circuits (VLSI), e.g. Microcomputers. Graphical User Interfaces (GUIs), networks.5th generation (1985-present): Multimedia interfaces, mobile computing, artificial intelligence applications, parallel processing. Most of today’s computers also inherit the properties of 4th generation devices.

Recent development: The Internet

Prior to the mainstream application of the internet, networks for specialist research groups and the military existed.More info: http://www.walthowe.com/navnet/history.html

One such research group is the community of particle physicists, and there was a project at the European Particle Physics Laboratory in Geneva (CERN) where the WWW with its hypertext and links was invented by Sir Tim Berners-Lee.

Recent development: The Internet

Website of CERN:

http://public.web.cern.ch/Public/Welcome.html

Other major development under the influence of CERN: Grid Computing

Website of Tim Berners-Lee:http://www.w3.org/People/Berners-Lee/

Question to you

What is a server?

An answer to this question is provided in the lecture. If you miss the lecture, you can find a good summary at:

http://ask-leo.com/so_just_what_is_a_server_anyway.html

New challenges

Electronic commerce (amazon, easyjet, etc.)Security threats and protection issues (firewalls)File sharing over the internet (music files, movies)Problem of Plagiarism (never copy other people’s assignments if they are available online – as this is considered a serious offence)Legal issues (copyright)

MEMORY

Main memory:• stores data currently being used• is made of semiconductor chips• mostly temporary: data are lost when power is off

Secondary memory:• for mass storage • magnetic: hard disks, floppy discs)• or visual: CD ROM, DVD• cheap

The following demonstration is based on Francis Lin’s lecture notes. The demonstration can be found in full length by downloading the file from the following links:http://www.doc.gold.ac.uk/~mas01fl/teaching/cis106/week2/memarchit.dochttp://www.doc.gold.ac.uk/~mas01fl/teaching/cis106/week2/memconcepts.doc