Univers ity of Utah 1 ENIAC • First fully-electronic, general-purpose programmable computer • Built 1943-1946
University
of Utah
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ENIAC
• First fully-electronic, general-purpose programmable computer
• Built 1943-1946
University
of Utah
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Background History
• Artillery gun "firing tables"• Computed by hand• "Computers" were people
University
of Utah
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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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of Utah
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Background History
• Army accepts proposal!- Why?
Wartime desperation? Humiliation from atom bomb experience? New application of existing technology?
University
of Utah
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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
University
of Utah
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ENIAC Design
• Three main parts:- Math units- Memory units- “Master programmer”
• Wired together via cables
University
of Utah
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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
University
of Utah
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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 > 9
University
of Utah
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ENIAC Design
• Speed- 5000 additions per second- Multiplication: 2.6 milleseconds- Square root: 25 milleseconds
University
of Utah
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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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of Utah
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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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of Utah
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ENIAC Design
• Quality standards- Used best vacuum tubes available
< 10% recommended voltage Always powered on Broken tubes once every 2 days
- "Least appetizing" wires- Custom-designed knobs
University
of Utah
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Programming
• No "programming" in the modern sense of the word.
• Manually set dials and plug in cables
University
of Utah
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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!
University
of Utah
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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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of Utah
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Other Early Computers
• Konrad Zuse- Another early pioneer- Z1 (mechanical)- Z3 (electromechanical)- Z4 (electronic)
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of Utah
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Other Early Computers
• Atanasoff-Berry Computer (ABC)- 1937- All-electronic- Not general-purpose
Designed to solve linear equations
University
of Utah
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Patent Problems
• ENIAC patent 1964• Honeywell vs Sperry-Rand (1973)
- invalidated patent- ABC declared first computer- computers are public domain
University
of Utah
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Please note...
• Today is last of "pre-history"• Wednesday we start with the textbook