cs 185c/286: the history of computing november 28 class meeting department of computer science san...

CS 185C/286: The History of Computing November 28 Class Meeting

Department of Computer ScienceSan Jose State University

Fall 2011Instructor: Ron Mak

www.cs.sjsu.edu/~mak

Department of Computer ScienceFall 2011: November 28

CS 185C/286: History of Computing© R. Mak

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Dan Greiner

History of Computing Speaker Wednesday, Nov. 30, 6:00-7:00 PMAuditorium ENGR 189 Reception before the talk in

ENGR 294 at 5:00 PM

“Legacy of the IBM System/360 Architecture” IBM “bet the company” on this

architecture in the early 1960s Is it still relevant today after

nearly 50 years?



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Research Project Reports

Due Monday, Dec. 12 (first day of finals week) What you’ve posted to the IEEE Global History Network Any attachments (software, etc.)

Report grading Quality of your research

What were your primary and secondary resources? Whom did you interview? What questions did you ask? How well did you solicit and respond to criticism and advice?

Quality of your final deliverable

Final grade 33% attendance + essays 67% project



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SAGE Computer System

An intercontinental air-defense network commissioned by the U.S. military “Semi-Automatic Ground Environment” Started in the 1950s and operational by 1963 Operational until 1983 Total cost: $8-12 billion in 1964

Designed to coordinate radar stations Detect atomic bomb-carrying Soviet bombers and guide

American missiles to intercept and destroy them Linked by long-distance telephone to radar defense sites

large-scale wide-area computer network 23 “direction centers” each with a SAGE computer that could

track as many as 400 airplanes concrete-hardened bunkers across the US and Canada



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Designed by Jay Forrester and George Valley Professors at the MIT Lincoln Laboratory Forrester (1918- ) also developed core

memory Largest and most expensive

computer system 250 tons 60,000 vacuum tubes

13,000 transistors > 150 CRT monitors each

with a light gun ~3 MW of power 800 programmers Built by IBM



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SAGE Computer System Specifications

Architecture duplex CPU, no interrupts, 4 index registers 32-bit words 75K instructions/second

Memory 4 banks of 64K words, 6 us cycle time 150K words magnetic drum 4 tape drives, ~100K words each

I/O keyboard CRT with light gun teletype with 1300 bps modem



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The IBM 7030 Stretch

World’s fastest computer from 1961-1964 The CDC 6400 was faster starting in 1964

IBM’s first transistorized supercomputer “A giant step” that “stretched” existing computer technology Hardware-supported parallelism

First one delivered to Los Alamos National Laboratory

Considered an embarrassing failure by IBM_



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Business Context

In April 1955, the UC Radiation Laboratory at Livermore processed bids to build a high-performance 2 MHz decimal computer system called the Livermore Research Computer (LARC) for $2.5M IBM proposed a machine that would be 4 to 5 times faster but

for $3.5M to be delivered in 42 months Univac won the bid with a proposal to deliver in 29 months

In September 1955, IBM proposed to deliver a supercomputer to the Los Alamos National Laboratory Worried that Los Alamos would also order a LARC Binary computer with “speed at least 100 times”

that of the IBM 704 IBM won the proposal in November 1956

$4.3M contract with delivery in 1960



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IBM 704

First mass-produced computer with floating-point hardware

Introduced in 1954 123 systems sold

from 1955 to 1960

Core memory One 38-bit accumulator One 36-bit quotient

register Three 15-bit index

registers

FORTRAN and Lisp were developed on a 704



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Famous IBM 7030 Stretch Developers

Project manager: Stephen Dunwell, 1913-1994 Had 180 people by 1957

Hardware designer: Gene Amdahl Left IBM when passed over by Dunwell (rehired in 1960)

Fred Brooks Later led the IBM System/360

John Backus Inventor of FORTRAN Backus-Naur Form (BNF)

John Cocke and Harwood Kolsky Wrote a simulator for the Stretch architecture Cocke later became “the father of RISC architecture” Kolsky is now a UC Santa Cruz emeritus professor



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Stephen Dunwell

Stephen Dunwell (left) and Erich Bloch (right)



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IBM 7030 Stretch Customers

Machine name

Built Customer Delivery

X-1 Poughkeepsie Los Alamos Scientific Lab (LASL) 1961

K-1 Kingston Livermore Radiation Lab (LRL) [now LLNL] 1961

K-2 KingstonAtomic Weapons Research Establishment (AWRE), Aldermaston, UK

1962

K-3 Kingston US Weather Bureau [now NWS] 1962

K-4 Kingston Naval Weapons Lab (Dahlgren) 1962

K-5 Kingston MITRE Corporation 1962

K-6 KingstonCommissariat a l'Energie Atomique (CEA), France

1963

7950 (Harvest)

Poughkeepsie National Security Agency (NSA) 1962

A ninth Stretch was built and kept by IBM.



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IBM 7030 Stretch Features

8-bit byte

Instruction pipelining and prefetch (lookahead) Start slower memory operand fetches early and overlap them

with the operation of the fast floating-point arithmetic unit

Memory interleaving Up to 6 banks of memory

Error correcting memory One-bit errors automatically corrected Two-bit errors (unlikely) caused the running program to be

interrupted temporarily for a memory refetch



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IBM 7030 Stretch Features Multiprogramming

One running program can interrupt another program running at a lower priority

Memory protection

Rich instruction set Decimal or binary

operation Radix conversion Floating point Indexing Variable-length operands

Standard Modular System (SMS) cards



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Failure ...

Despite all the architectural innovations, the Stretch was not 100 times as fast as the IBM 704 Benchmarks showed that it was only 30 times faster

Major embarrassment to IBM Only 9 systems were built Originally priced at $13.5M, reduced to $7.8M

Stephen Dunwell was made the scapegoatand demoted to a staff position



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Postmortem Analysis

System performance was overhyped in the beginning Overly complex design

Features were added without proper cost-benefit analyses

System simulations were started late Kolsky reported that the simulation results were

“generally disregarded” anyway

Series of transistor budget cuts Reductions in the number of transistors

Transistors were only half the predicted speeds Memory accesses, particularly the registers, were slower

Early arithmetic operation timings were over-optimistic



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Postmortem

“The fact that the overall performance has dropped by only a factor of 3 in view of these difficulties is greatly to the credit of the engineers.” [Kolsky]_



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IBM 7030 “Stretch” Legacy

Most of the core architectural features of the IBM System/360 were pioneered by the Stretch

Features such as instruction pipelining and prefetch, and memory interleaving are used today in the IBM PowerPC_



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... and Redemption

IBM CEO Tom Watson Jr. eventually recognized the important contributions of the Stretch

At IBM’s Annual Awards Dinner in March 1966, Stephen Dunwell was named an IBM Fellow_

cs 185c/286: the history of computing november 28 class meeting department of computer science san...

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