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Computer Science –

• Where do we begin?
  - Let’s begin with some background information
  - Computer Science is not the study of computers
  - Computer Science is the study of algorithms

Algorithms – a brief history

• The word algorithm was not listed in Webster’s New World Dictionary until 1957
• An older form "ALGORISM", which is the process of doing arithmetic using Arabic numerals

Algorithm

• The word is derived from the last name of a famous Persian mathematician
  - Muhammad ibn-Musa Al-Khowarizimi
• He was also an author in the 8th and 9th centuries and wrote a book about the base-10 positional numbering system

What is an algorithm?

• It is a well-ordered collection of unambiguous and effectively computable operations that, when executed, produces a result and halts in a finite amount of time.
  An Invitation to Computer Science Schneider, et al, 1999

Why is this important?

• If we can specify an algorithm, we can automate the solution
  - a computing agent can carry it out
  - is able to understand and perform instructions
  - humans, robots, computers

What about computers?

• The need for fast numeric calculation inspired Charles Babbage (1823) to start building his difference engine – a complex mechanical machine for calculating logarithms and trigonometric functions
• Construction of tables for ballistics calculations

Analytic Engine

• In the midst of constructing the difference engine, amongst financial and technical difficulties, Babbage started to design a much more flexible, general purpose machine – the Analytic Engine

Analytic Engine Concepts

• Four main components of modern computers -
  input
  processing
  storage
  output

Lady Ada Lovelace

• Worked closely with Babbage on his design and she used her mathematical and literary skills to promote the analytical engine
• Often called the first programmer because she wrote a program to calculate Bernoulli numbers using the analytical engine

Calculating Machines

• Babbage was unsuccessful in completing his vision
• Complex calculating machines were constructed and in 1890, the first US census was counted with the help of a ‘tabulating machine’ developed by Herman Hollerith, whose company in 1924, became International Business Machines Corp (IBM)

World War II

• Electronic Numerical Integrator and Computer (ENIAC) was developed as a general-purpose electronic digital computer
• Used to calculate missile trajectories
• Completed in 1946, used 18,000 vacuum tubes, 500 miles of wire and weighed more than 35 tons

Grace Hopper

• A US Navy Commodore, also a mathematician who worked on early computers
• Wrote the first paper on compilers (programs that translate instructions into the 1s and 0s the computer understands)
• Created the first programming language, COBOL, that could be used on more than one machine

Shift in Use

• Main use of computers has shifted from calculation to communication
• Development of the microprocessor in the 1970s initiated the personal computer
• Small enough and cheap enough to have on your desk or in your home
• ‘paperless office’ had opposite effect – computers could not communicate between each other

Communication

• LAN (Local Area Network) allowed computers within an organization to communicate with each other
• Mid-1980s computers popular in the home market, could not speak directly with each other – many had different operating systems (Mac vs. PC)
• No uniform way to describe and transform information across computing platforms