History of Computing

Define a computer before 1935?

What is the definition after 1945?

History of Computing

Define a computer before 1935?– A person that computes or performs arithmetic

calculations

What is the definition after 1945?– An electronic device for performing arithmetic

calculations

History of Computing

What motivated the need for computing machines?

History of Computing

What motivated the need for computing machines?– Complex and tedious arithmetic calculations

History of Computing

What are some example tedious calculations that were performed that motivated the need for computing machines?

History of Computing

What are some example tedious calculations that were performed that motivated the need for computing machines?– Basic arithmetic (abacus)– Navigation and Mathematical tables (Babbage)– Flight trajectory tables (WWII)– Census (Eckert and Mauchley, UNIVAC)– Inventory and budget (J. Lyons)

History of Computing

What are some examples of early computing machines (mechanical computers)?

History of Computing

What are some examples of early computing machines (mechanical computers)?– Abacus (~5000 yrs ago)– Slide rule (Outred, 1600s)– Pascaline (Blaise Pascal, 1600s)– Difference engine (Charles Babbage, 1822)– Tabulating machine (Herman Hollerith, 1890)

History of Computing

What was the purpose of Babbage’s Difference Engine?

History of Computing

What was the purpose of Babbage’s Difference Engine?Calculation of mathematical tables: evaluating mathematical

functions for sequences of values using the method of finite differences

History of Computing

What was the purpose of Babbage’s Difference Engine?Calculation of mathematical tables: evaluating mathematical

functions for sequences of values using the method of finite differences

History of Computing

Why did Babbage want to create the Analytical Engine even after having increasing demand for his Difference Engine?

History of Computing

Why did Babbage want to create the Analytical Engine even after having increasing demand for his Difference Engine?

The Difference Engine was still fixed in purpose. He wanted to design a programmable machine.

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What was a major significance of the Analytical Engine towards the progress of computing?

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What was a major significance of the Analytical Engine towards the progress of computing?

• First time someone designed a machine independent of its ultimate purpose.

• Birth of distinction between software and hardware

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Who worked closely with Babbage during the development of the Analytical Engine and is credited as the first computer programmer?

History of Computing

Who worked closely with Babbage during the development of the Analytical Engine and is credited as the first computer programmer?

Ada Lovelace, daughter of the poet Lord Byron

Programming language Ada is named after her.

History of ComputingHow were numbers represented and stored in the

mechanical computers?

History of ComputingHow were numbers represented and stored in the

mechanical computers?Positions of beads: abacus (~5000 years ago)

History of ComputingHow were numbers represented and stored in the

mechanical computers?Orientation of number wheels: Pascal’s Pascaline (1600s)

History of ComputingHow were numbers represented and stored in the

mechanical computers?

Orientation of gears:

Babbage’s difference engine

(1822)

History of ComputingHow were numbers represented and stored in the

mechanical computers?Arrangements of holes in a punch card: Herman Hollerith

(1890)

History of Computing

How were numbers represented in modern computers?

History of Computing

How were numbers represented in modern computers?

• A series of 2-way switch settings• Binary representation, streams of 0s and 1s

History of Computing

How were numbers represented in modern computers?

• A series of 2-way switch settings• Binary representation, streams of 0s and 1s

Why binary?

History of Computing

How were numbers represented in modern computers?

• A series of 2-way switch settings• Binary representation, streams of 0s and 1s

Why binary?

• Because binary digit (bit) easier to represent:– Only 2 states: On/off, high/low, in/out, up/down,…

History of Computing

Why were binary digits fundamental to electronic computers?

History of Computing

Why were binary digits fundamental to electronic computers?

Engineering simplicity!Used on/off switches to represent binary digits (bits):

– Relays, vacuum tubes, transistors, integrated circuits

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Why didn’t mechanical computers need binary numbers?

History of Computing

Why didn’t mechanical computers need binary numbers?

• Unnecessary to perform number conversion • They were able to easily distinguish more than 2 states

per digit

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Why was the vacuum tube so important to computer development?

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Why was the vacuum tube so important to computer development?

• SPEED!• Fast switching between binary states• 1000 times faster than relay (Colossus)

For what tradeoffs?

History of Computing

Why was the vacuum tube so important to computer development?

• SPEED!• Fast switching between binary states• 1000 times faster than a relay (Colossus)

For what tradeoffs?• Reliability and cost!

History of Computing

What replaced the vacuum tube and completely revolutionized computers in 10 years?

History of Computing

What replaced the vacuum tube and completely revolutionized computers in 10 years?

Transistors

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What eventually replaced transistors?

Integrated circuits (ICs)

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What did relays, vacuum tubes, transistors, and integrated circuits all have in common for their use in computers?

History of Computing

What did relays, vacuum tubes, transistors, and integrated circuits all have in common for their use in computers?

All acted as a 2-way switch that represented a single bit of information

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Most early computers were constructed only to perform tedious arithmetic calculations. What was special about the machine Colossus that Alan Turing helped design? What was its purpose?

History of Computing

Most early computers were constructed only to perform tedious arithmetic calculations. What was special about the machine Colossus that Alan Turing helped design? What was its purpose?

• Manipulated language symbols not just numbers• Breaking German codes (U-boat attacks on British)

History of Computing

Describe Turing’s vision of what a computer is or should be?

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Describe Turing’s vision of what a computer is or should be?

• Symbol manipulator not just numerical machine

• A learning machine

• A machine that exhibits some intelligence

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What is the Turing test?

History of Computing

What is the Turing test?

A test devised by Alan Turing to determine if a machine could be considered to possess some intelligence.

After 5 minutes, if a person asking a remote entity questions was not sure if the entity was human or machine, then the computer could be said to possess some intelligence.

History of Computing

Your thoughts…

Do you think this test was sufficient?

What would make you believe that a machine had intelligence?

Do you consider this to be a danger? Why?

History of Computing

What were computers intended to replace?

History of Computing

What were computers intended to replace?

Large groups of people performing tedious, repetitive tasks such as arithmetic calculations and various bookkeeping.

Your thoughts… Was this really a bad thing? Were people’s fears justified? Will this replacement of humans by machines continue?

History of Computing

Your thoughts…

How were computers portrayed in the early years of computing (think UNIVAC times)?

How are they portrayed now?

Are there as many misconceptions and fears today? Why or why not?