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IBM

• Dominates the industry• Critics complain that IBM doesn't

innovate- Sound familiar?

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IBM 7090 / 7094

• Transistorized version of IBM 709• The “classic” mainframe!

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of Utah

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IBM 7094

• 150 K memory• 36-bit word length• As fast as a PC in 1980's

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of Utah

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Backwards compatibility

• IBM's golden handcuffs...• 704 → 709 → 7090 → 7094

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Smaller machines

• IBM 1401 (1959)• >10,000 installed!• Sometimes used as a peripheral for

larger computers

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Disk Drives

• First suggested by Eckert (1940's)• Engineered by IBM (1956)

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of Utah

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Disk Drives

• IBM RAMAC- “Random Access Memory Accounting

Machine”- 50 aluminum disks- 24 inch diameter- 1200 rpm- 5 million characters

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of Utah

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Mainframe Era

• Never left idle!• Not interactive

- programmers did not use the machine directly

• Data available as printouts

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of Utah

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Software

• Didn't exist as we know it at first- ENIAC's cables and dials- Machine language

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Early tools

• Separate machine for programming- Harvard Mark III- Zuse “Plan Preparation Machine”

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Breakthrough #1

• Use the computer as its own “plan preparation machine!”

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Breakthrough #2

• Reuse previously-written routines• Origin of term “compiler”

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Grace Hopper

• First “modern” programmer- Harvard Mark III calculator- UNIVAC

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Precursors

• Whirlwind computer's “Translation program”- Similar to modern compilers- Not general purpose- Slow

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Precursors

• Assembly language- Each “keyword” corresponds to a single

machine language instruction- Popular until 1980s/1990s

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Users Groups

• SHARE- “Society to Help Avoid Redundant Effort”- IBM 701/704 users- Shared code routines for common problems

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of Utah

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Sorting

• “Files” on magnetic tape• Sorted alphabetically/numerically• What happens if you change (or add or

delete) a file?

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Sorting

• Not just an academic exercise- Matter of business survival!

• UNIVAC's first software was a tape-sorting routine- Written by Betty Holberton

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FORTRAN

• “Formula Translation”• Designed for IBM 704 (1957)• Syntax similar to algebra• Machine-specific commands

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2020

FORTRAN

• Many revisions- FORTRAN II, III, IV- FORTRAN 66, 77, 90- FORTRAN 95, 2003, 2008

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FORTRAN

• Still used today!- Supercomputers- Benchmarks

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COBOL

• Common Business Oriented Language (1960)

• Inspired by Grace Hopper's compilers for UNIVAC

• Cross-platform by design

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COBOL

• “Self documenting” verbose code

C:if (employeeHours > maximum)

COBOL:IF EMPLOYEE-HOURS IS GREATER THAN MAXIMUM

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COBOL

• There's more than one way to do it!

COMPUTE X = (-B + (B ** 2 - (4 * A * C)) ** .5) / (2 * A)

MULTIPLY B BY B GIVING B-SQUARED.

MULTIPLY 4 BY A GIVING FOUR-A.

MULTIPLY FOUR-A BY C GIVING FOUR-A-C.

SUBTRACT FOUR-A-C FROM B-SQUARED GIVING RESULT-1.

COMPUTE RESULT-2 = RESULT-1 ** .5.

SUBTRACT B FROM RESULT-2 GIVING NUMERATOR.

MULTIPLY 2 BY A GIVING DENOMINATOR.

DIVIDE NUMERATOR BY DENOMINATOR GIVING X.

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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!)