CSCI-235Micro-Computers in Science

Course Information & Introduction

• Class webpagehttp://www.stfx.ca/people/igondra/csci235

• What is a computer?A good start at defining what a computer is might be: “It is a device that processes data and produces information”

• Is this a good definition?It is far too broad in its applicability. With this definition, many things can be classified as a computer (e.g., a thermostat, a VCR)

• What is this definition missing?Have you ever written a term paper on your VCR or calculated your tax return with your thermostat?

Those devices were manufactured with the ability to perform a single, limited task

• A computer can be programmed!There is a particular kind of data that a computer requires in addition to any other data it might receive: a program

Better definition: “It is a programmable device that processes data and produces information”

Is the human brain a computer?

• Gross AnatomyHardware: equipment associated with the computer

• Input devices, processor, output devices, storage

Software: instructions that tell the hardware what to do

Two categories of software:• System software• Application software

• von Neumann ArchitectureAlthough specific components may vary, virtually all modern computers have the same underlying structure

known as the von Neumann architecture

Named after computer pioneer, John von Neumann, who popularized the design in the early 1950's

• The von Neumann architecture identifies 3 essential components:Input/Output Devices (I/O) allow the user to interact with the computer

Memory stores information to be processed as well as programs (instructions specifying the steps necessary to complete specific tasks)

Central Processing Unit (CPU) carries out the instructions to process information

• First “computer”?The first actual calculating mechanism known to us is the abacus, which was invented about 2000 years ago

Many references cite the French mathematician, physicist, and theologian Blaise Pascal as being the inventor of the first mechanical calculator in 1642, the Arithmetic Machine

However, it now appears that the first mechanical calculator may have been conceived by someone else almost 150 years earlier than Pascal's machine. Can you guess who?

• Leonardo Da Vinci

In the early 1800s, a French silk weaver called Joseph-Marie Jacquard invented a way of automatically controlling the warp and weft threads on a silk loom by recording patterns of holes in a string of cards

The first device that might be considered to be a computer in the modern sense of the word was the Difference Engine to automatically calculate mathematical tables conceived in 1822 by the British mathematician and inventor Charles Babbage

The Difference Engine was only partially completed when Babbage conceived the idea of another, more sophisticated machine called the Analytical Engine

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

Working with Babbage was Augusta Ada Lovelace, the daughter of the English poet Lord Byron. Ada, who was a splendid mathematician and one of the few people who fully understood Babbage's vision, created a program for the Analytical Engine

Ada is now credited as being the first computer programmer and, in 1979, a modern programming language was named ADA in her honor

In 1939, a German engineer, Konrad Zuse built the first programmable, general-purpose digital computer. His computer was built from electric relays to automate engineering calculations

• “I was too lazy to calculate and so I invented

the computer.”

John Atanasoff invented the Atanasoff-Berry Computer (ABC) —the first electronic digital computer. Built in 1939, this computer used vacuum tubes and was based on binary arithmetic. It was never a fully operational product

In 1944, Howard Aiken completed the Mark I, the largest electromechanical calculator ever built. It was built with electromechanical relays and followed instructions punched in paper tape

• The first computer “bug”

In 1945, Mauchly and Eckert built the ENIAC (Electronic Numerical Integrator and Computer). The ENIAC was built with 18,000 vacuum tubes that failed on an average of once every seven minutes

After the war, they created the UNIVAC I - the first general-purpose commercial computer

• First-Generation Computers1930s – 1940s

Vacuum tubes used as switches

Large computers

Extremely slow by today’s standards

Prone to frequent failure

Includes the ABC, Mark I, ENIAC, UNIVAC,and others of similar design

• Second-Generation Computers1950s – mid-1960s

Transistors used as switches

Smaller than vacuum-tube-built computers

As much as a thousand times faster than first-generation computers

More reliable and less expensive

• Third-Generation ComputersLate 1960s

Hundreds of transistors packed into a single integrated circuit on a silicon chip

Dramatic reduction in size and cost

Significant increases in reliability, speed, and efficiency

Mass production techniques to manufacture chips inexpensively

• Fourth-Generation Computers1970s to present

Complete computer on a chip

Radical change in the appearance, capability and availability of computers