Transcript computer - Computational Science

CPS 101 Introduction to
Computational
Science
Wensheng Shen
Department of Computational Science
SUNY Brockport
Chapter 1: Computer
History
http://www.computersciencelab.com/ComputerHistory/History.htm
• Prehistory of
computers
A computer is a machine for manipulating data according to a list of instructions.
Abacus
Abacus can add human memory and perform the repetitive calculations.
Fast in addition and subtraction but not multiplication and division.
The Babylonians used dust abacus as early as 2400 BC. China played an
essential part in the development and evolution of the abacus.
Slide rule
• A slide rule was first built in England
in 1632.
• Used in the 1960's by the NASA
engineers
– Mercury
– Gemini
– Apollo
Pascaline
-Invented by Pascal in 1642.
- One-function calculator
- Pascal built 50 of them.
-The cost was very high
- Not accurate
Jacquard loom
Invented in late
1700’s
for weaving silk
Program on punch
cards
each hole
lifts a set of threads
thread is lifted if
any controlling hole
punched
Punched cards
By selecting particular cards for Jacquard's loom you defined the woven pattern
Difference engine
- Compute logarithm tables.
- Built by Charles Babbage using government funds.
- Important for ocean navigation.
Hollerith desk
• Hollerith desk
– Population count, census machine.
• Hollerith built a company
– the Tabulating Machine Company
– International Business Machines IBM
The Harvard Mark I
- Was built as a partnership between Harvard and IBM in 1944.
-This was the first programmable digital computer made in the U.S.
- It was not a purely electronic computer.
- It was constructed out of switches, relays, rotating shafts, and clutches.
-The machine weighed 5 tons, incorporated 500 miles of wire, was 8 feet tall
and 51 feet long, and had a 50 ft rotating shaft running its length, turned by a 5
horsepower electric motor. The Mark I ran non-stop for 15 years.
Grace Hopper
- found the first computer "bug": a dead moth that had gotten
into the Mark I and whose wings were blocking the reading of
the holes in the paper tape.
- is credited with coining the word "debugging" to describe the
work to eliminate program faults
High-level language
compiler
Binary language
• Grace Hopper designed the first
compiler
• A compiler -- to translate it into
the binary language of the
computer and hence Grace
Hopper also constructed the
world's first compiler
Performance of Mark I
Mark I
Can work on 23 digit wide numbers:
Addition and subtraction: 3/10th second
Multiplication: 4 seconds
Division: 10 seconds
Storage: 72 numbers
Personal computer
Numbers are fetched from RAM at a few
billionths of a second, and from hard disk
at a few thousandths of a second.
Storage: hundreds of millions of numbers
in RAM, and hundread of billions of
numbers in hard disk.
Reason: mechanic versus electronic
Electronic Digital Computers
• 1st generation computers
– Vacuum tube, 1946-1957, 40K operations/sec
• 2nd generation computers
– Transistor, 1958-1964, 200 K operations/sec
• 3rd generation computers
– SSI, MSI, 1965-1971, 1 M operations/sec
• 4th generation computers
– LSI, 1972-1977, 10 M operations/sec
• 5th generation computers
– VLSI, 1978 to date, 100 M operations/sec
Electronic digital computers
• The first generation: Vacuum Tubes
A vacuum tube
- a device used to amplify, switch or modify a signal.
- Projector
ENIAC: Electronic Numerical
Integrator and Computer
• ENIAC
– forefather of today’s all-electronic digital computers.
– built at the University of Pennsylvania between 1943 and
1945 by two professors, John Mauchly and the 24 year
old J. Presper Eckert
– weighed 30 tons
– used more than 18,000 vacuum tubes
– Can only be operated in a specially designed room with a
heavy duty air conditioning system
ENIAC - background
• Electronic Numerical Integrator And
Computer
• Eckert and Mauchly
• University of Pennsylvania
• Trajectory tables for weapons
• Started 1943
• Finished 1946
– Too late for war effort
• Used until 1955
Univac (first commercial computer
in US): Election, Nov. 4, 1952
Candidate
Eisenhower
Stevenson
Electoral votes
Univac prediction
438
93
Actual count
442
89
Harold Sweeney, operator
J. Presper Eckert, co-inventor
Walter Cronkite, CBS
USA TODAY; Oct 27, 2004; pg. B.3
The von Neumann Machine
Arithmetic Logic Unit
I/O
Equipment
Main
memory
Program control unit
Stored-program concept: a computer could get its instructions by reading them
from memory, and a program could be set or altered by setting the values of a
portion of memory. The idea is attributed to the ENIAC designers, most notably the
mathematician John von Neumann.
The von Neumann machine is also called IAS computers, since it was designed and
completed at the Princeton Institute for Advanced Studies.
The general structure of IAS
computer
• A main memory: stores both data
and instruction
• An arithmetic-logical unit (ALU): is
capable of operating on binary data
• A control unit: interprets the
instructions in memory and causes
them to be executed
• Input and output (I/O):
communicates to outside
Von Neumann - Biography
Born 28 December 1903, Budapest, Hungary; Died 8 February 1957, Washington DC; Brilliant
mathematician, synthesizer, and promoter of the stored program concept, whose logical design of the IAS
became the prototype of most of its successors - the von Neumann Architecture.
Von Neumann was a child prodigy, born into a banking family is Budapest, Hungary. When only six years old he could
divide eight-digit numbers in his head. He received his early education in Budapest, under the tutelage of M. Fekete, with
whom he published his first paper at the age of 18. Entering the University of Budapest in 1921, he studied Chemistry,
moving his base of studies to both Berlin and Zurich before receiving his diploma in 1925 in Chemical Engineering. He
returned to his first love of mathematics in completing his doctoral degree in 1928. he quickly gained a reputation in set
theory, algebra, and quantum mechanics. At a time of political unrest in central Europe, he was invited to visit Princeton
University in 1930, and when the Institute for Advanced Studies was founded there in 1933, he was appointed to be one of
the original six Professors of Mathematics, a position which he retained for the remainder of his life. At the instigation and
sponsorship of Oskar Morganstern, von Neumann and Kurt Gödel became US citizens in time for their clearance for wartime
work. There is an anecdote which tells of Morganstern driving them to their immigration interview, after having learned
about the US Constitution and the history of the country. On the drive there Morganstern asked them if they had any
questions which he could answer. Gödel replied that he had no questions but he had found some logical inconsistencies in the
Constitution that he wanted to ask the Immigration officers about. Morganstern strongly recommended that he not ask
questions, just answer them!
During 1936 through 1938 Alan Turing was a graduate student in the Department of Mathematics at Princeton and did his
dissertation under Alonzo Church. Von Neumann invited Turing to stay on at the Institute as his assistant but he preferred to
return to Cambridge; a year later Turing was involved in war work at Bletchley Park. This visit occurred shortly after Turing's
publication of his 1934 paper "On Computable Numbers with an Application to the Entscheidungs-problem" which involved
the concepts of logical design and the universal machine. It must be concluded that von Neumann knew of Turing's ideas,
though whether he applied them to the design of the IAS Machine ten years later is questionable. [5]
•http://ei.cs.vt.edu/~history /VonNeumann.html
Electronic digital computers
• The second generation: transistors
- A semiconductor device
- Can amply, switch, and modify electrical signals.
- The fundamental building block of the electrical circuit.
Transistors
• Replaced vacuum tubes
• Smaller
• Cheaper
• Less heat dissipation
• Made from Silicon (Sand)
• Invented 1947 at Bell Labs
• William Shockley et al.
Transistor Based Computers
• Second generation machines
• IBM 7000
• DEC - 1957
Electronic digital computers
• The third generation: integrated circuits
Cost and performance:
-Cost is low. They are printed as a unit and not
constructed a transistor at a time.
Performance is high.
- components switch quickly and consume little
power.
- As of 2006, with up to 1 million transistors per
mm2.
Incompleteness Theorem
• In 1931, the Czech-born
mathematician Kurt Gödel (19061978) demonstrated that within any
given branch of mathematics.
• Gödel's Theorem has been used to
argue that a computer can
never be as smart as a
human being because the
extent of its knowledge is limited by
a fixed set of axioms, whereas
people can discover unexpected
truths.
Computers and humans
• "Computers are
incredibly fast, accurate,
and stupid; humans are
incredibly slow,
inaccurate and brilliant;
together they are
powerful beyond
imagination." --- Albert
Einstein
1921 Nobel Prize in Physics for photoelectric effect. In 1999 Einstein
was named Time magazine's "Person of the Century", and a poll of
prominent physicists named him the greatest physicist of all time