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Fortran Assignment

• Due tonight @ 7:30pm• Questions?

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Early 1960's Mainframe Companies

• Snow White (IBM)• Seven Dwarfs

- Control Data, Honeywell, Philco, Burroughs, RCA, GE, NCR

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IBM in 1961

• 7090/7094- large scientific mainframe

• 1401- small mainframe

• 7070- “business” version of 7090

• 1620- another small mainframe

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IBM in 1961

• 7090/7094- large scientific mainframe

• 1401- small mainframe

• 7070- “business” version of 7090

• 1620- another small mainframe

ALL

INCOMPAT

IBLE!

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SPREAD

• Committee at IBM (1961)- Current machines not scalable- What to do about it?

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The Answer

• One unified product line- for business AND science

• “Bet the company”

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System/360

• A family of related machines- 25:1 performance ratio

• All binary-compatible with each other!!!- Same executables run on each model of 360

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How?

• Microprogramming- Same instruction set- But implemented differently for each

machine!

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Gallery

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Gallery

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Gallery

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Lasting trends

• System/360 used 8-bit “bytes”• 32-bit word length• General-purpose registers

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EBCDIC

• “Extended Binary Coded Decimal Interchange Code”

• Two standards- ASCII for minicomputers- EBCDIC for mainframes

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Emulators

• 360 included emulation modes for- 7000-series- 1401

• Customers could migrate existing applications- Sorry, Honeywell!

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Operating Systems

• OS/360- Too late!

• Stopgaps- BOS, TOS, DOS

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Famous People

• Gene Amdahl- “Amdahl's Law”- Principle designer of System/360

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Famous People

• Fred Brooks- “The Mythical Man-Month”

Based on experiences writing OS/360

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Summary

• System/360- extremely successful!- first “line” of computers- established many current conventions

• Direct ancestor of IBM's current mainframes!

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Next Homework

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of Utah

2020

Multimedia

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Friday

• Guest speaker: Lee Hollaar

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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!)