ENIAC

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ENIAC

• First fully-electronic, general-purpose
  programmable computer
• Built 1943-1946

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Background History

• Artillery gun "firing tables"
• Computed by hand
• "Computers" were people

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Background History

• Herman Goldstine
• Army lieutenant in charge of firing tables
• John Mauchly and Presper Eckert
• Professors at U. of Pennsylvania
• Idea for electronic calculating machines

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Background History

• Army accepts proposal!
• Why?
• Wartime desperation?
• Humiliation from atom bomb experience?
• New application of existing technology?

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Background History

• Built it in-place on first floor of engineering
  building on U.Penn campus
• University assigns 12 people to project
• no senior faculty

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ENIAC Design

• Three main parts
• Math units
• Memory units
• Master programmer
• Wired together via cables

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ENIAC Design

• Twenty "accumulators"
• Base 10, not base 2
• Each could hold a 10-digit signed number
• Each digit had its own circuit

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ENIAC Design

• Counters
• Vacuum tubes, not electromechanical relays
• 10 flip-flops per digit
• each flip-flop consists of 2 vacuum tubes
• Converted electronic "pulses" to numbers
• "Carry pulse" if sum gt 9

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ENIAC Design

• Speed
• 5000 additions per second
• Multiplication 2.6 milleseconds
• Square root 25 milleseconds

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ENIAC Design

• Hackery
• Multiplication lots of additions
• "Multiplication table" had hard-coded answers to
  many multiplications
• Division square roots lots of subtractions
  and additions
• Constants entered via "function tables" or
  punched cards

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ENIAC Design

• Output
• Punched cards
• Neon lightbulbs

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ENIAC Design

• Physical dimensions
• 40 "panels"
• each panel 8.5 feet tall (2.6 m)
• 17,468 vacuum tubes
• 30 tons

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ENIAC Design

• Quality standards
• Used best vacuum tubes available
• lt 10 recommended voltage
• Always powered on
• Broken tubes once every 2 days
• "Least appetizing" wires
• Custom-designed knobs

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Pictures
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Pictures
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Pictures
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Pictures
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Programming

• No "programming" in the modern sense of the word.
• Manually set dials and plug in cables

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Programming

• Time to program
• Month to prepare a program
• 2 days to set up a program
• 1 week to debug
• Usability was an afterthought!

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Timeline

• Finally finished in 1946
• (World War II was already over!)
• Dismantled and sent to Aberdeen Proving Ground
  (Maryland)
• Used for hydrogen bomb calculations
• Retired in 1955

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Demo
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Other Early Computers

• Konrad Zuse
• Another early pioneer
• Z1 (mechanical)
• Z3 (electromechanical)
• Z4 (electronic)

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Other Early Computers

• Atanasoff-Berry Computer (ABC)
• 1937
• All-electronic
• Not general-purpose
• Designed to solve linear equations

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Patent Problems

• ENIAC patent 1964
• Honeywell vs Sperry-Rand (1973)
• invalidated patent
• ABC declared first computer
• computers are public domain

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Please note...

• Today is last of "pre-history"
• Wednesday we start with the textbook

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Test Question

• On a scrap of paper, write a question that
  encapsulates one of the points from today's
  class, and turn it in.
• (Put your name on it!)