cosc 1306 computer science and programming jehan-françois pâris [email protected]
TRANSCRIPT
![Page 2: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/2.jpg)
CHAPTER ITHE COMPUTER
![Page 3: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/3.jpg)
Chapter Overview
The computing phenomenonPervasivenessComputers or computing?
Historical perspectiveFour predecessorsThe birth of computers Its evolution
![Page 4: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/4.jpg)
THE COMPUTING PHENOMENON
![Page 5: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/5.jpg)
Computers as life changers
They are everywhere They have changed our lives
Electronic mailWWWOnline order processingTicketless travel
![Page 6: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/6.jpg)
Case study
A friend of mine now teaches in a small University in Montevideo, Uruguay
![Page 7: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/7.jpg)
Then
Before the Internet, his life would have been difficultNo access to a good university libraryCould only communicate with colleagues
through Expensive international calls Slow Uruguayan postal service
Nearly total isolation from CS community
![Page 8: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/8.jpg)
Now
He hasFull access to research papers posted onlineCan communicate with colleagues through
Email, instant messages, Facebook, … Skype
Submits papers to conferences through WWW
We write papers together!
![Page 9: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/9.jpg)
My point
Internet has abolished distance Inexpensive personal computers allow us to
work virtually everywhere Still need a good Internet connection
Changed the lives of computer scientists and mathematicians working inSmall colleges in the boondocksDecent universities in developing countries
![Page 10: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/10.jpg)
Counterpoint
Human contacts still count:Main reason why scientists travel
No Internet access means exclusionCase of most African countries
![Page 11: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/11.jpg)
The iceberg
Most computing takes place where we do not see it
![Page 12: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/12.jpg)
Examples
Car computers Set-top box Digital television Fly-by-wire planes Smart phones Many medical appliances
![Page 13: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/13.jpg)
An analogy
Mid-nineteenth century big textile factories usedSteam-powered looms
One steam engine powered several loomsPower went through transmission belts and
pulleys Dangerous
![Page 14: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/14.jpg)
transmission belts
![Page 15: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/15.jpg)
An analogy (cont'd)
Stream engines were progressively replaced by electrical motorsQuickly found it was better to have one
smaller motor per loom Got rid of transmission belts Allowed more flexible plant layouts
Now electrical motors are everywhereCar power windows, razors, toothbrushes,
…
![Page 16: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/16.jpg)
How it applies
Started with a few giant "electronic brains" Replaced by time sharing computers and
individual terminals Moved to personal computers Each of us is now likely to have several
computing devices
![Page 17: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/17.jpg)
Counterpoint
Are we now living in the best of all possible worlds?
![Page 18: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/18.jpg)
Social problems
Lack of privacy
Distraction
Nothing is forgotten
![Page 19: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/19.jpg)
More pressing problems
What happens when computers that control critical aspects of our lives go wrong? In 1985 a Canadian-built radiation-treatment
device began blasting holes through patients' bodies. How a series of simple computer errors sabotaged a state-of-the-art medical wonder.
(http://www.ccnr.org/fatal_dose.html)
![Page 20: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/20.jpg)
The full report
An Investigation of the Therac-25 Accidents
Nancy Leveson, U of WashingtonClark S. Turner, UC Irvine
IEEE Computer, Vol. 26, No. 7, July 1993, pp. 18-41
http://courses.cs.vt.edu/cs3604/lib/Therac_25/Therac_1.html
![Page 21: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/21.jpg)
Another big problem
In fly-by-wire planes, pilots’ inputs are handled by an on-board computerWhat happens when pilots’ inputs conflict with
safety rules implemented in the on-board computer?
![Page 22: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/22.jpg)
The answer It depends
On Boeing planes, the pilot wins Great for airlines with highly-trained
pilots Not so good otherwise
On Airbus planes, the computer wins Great for airlines with not-so-well-trained
pilots Pilots can still override computer
![Page 23: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/23.jpg)
An outcome
On June 1, 2009 Air France flight 447 from Rio to Paris crashed in mid-AtlanticCause of crash was aerodynamic stallPreceded by problems with speed sensors
Inquiry noted that "pilots had not been trained to fly the aircraft in manual mode "
http://en.wikipedia.org/wiki/Air_France_Flight_447
![Page 24: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/24.jpg)
A long-term problem
An increasing large number of documents are exclusively stored in digital format without any hard copyMost of your recent picturesYour grades
Will they survive as well as hard copies do?
![Page 25: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/25.jpg)
The issues
Disk failures: Hard to figure exact mean time to fail of
hard drivesTen thousand to one million hoursTen thousand hours is slightly more than
11 yearsAn array of 150 disks will experience an
average of one failure per month
![Page 26: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/26.jpg)
The issues (cont’d)
Offline storage media become rapidly obsoleteWho can read a 5.25” floppy?A 4 MB floppy?A 100MB Zip disk?
![Page 27: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/27.jpg)
Can you read these?
On an old PCNoNo
![Page 28: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/28.jpg)
But you can still read this
![Page 29: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/29.jpg)
And this
![Page 30: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/30.jpg)
Or even this
SENATVS POPVLSQ[UE]The Senate and the people …
![Page 31: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/31.jpg)
That’s not all
Hard copies were easy to authenticateType of paper and ink that were usedTypewriter font
Electronic forgeries are harder to detectCan use digital signatures
Become easier to break over timePictures can be “Photoshopped”®
![Page 32: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/32.jpg)
My conclusion
We are not in the best of all possible worlds Rolling clock backward is not possible
The genie is out the bottle! Must understand the issues and push for action
Course will only help you with first part
![Page 33: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/33.jpg)
HISTORICAL PERSPECTIVE
![Page 34: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/34.jpg)
Three stages
The ancestors
The pioneers
The continuation
![Page 35: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/35.jpg)
The ancestors
Their contributions made computing possibleBlaise PascalJoseph Marie JacquardCharles BabbageSamuel MorseHerman Hollerith
All died well before computers were invented
![Page 36: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/36.jpg)
Blaise Pascal
Seventeenth-century French physicist, Christian polemist and philosopher
His contributionFirst adding machineHe patented it!
![Page 37: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/37.jpg)
La machine de Pascal
Could only add and subtract Costly to build Not a commercial success
![Page 38: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/38.jpg)
Long-term impact
Showed that arithmetic operations could be performed by mechanical devicesProof of concept
People kept building and using mechanical computing machines until the late sixties
![Page 39: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/39.jpg)
Joseph Marie Jacquard
Self-taught French inventor Invented in 1801 a mechanical loom
that simplified the weaving of fabrics with complex patterns (brocade, damask, …)
Key idea was to use punched cards to store the patterns
![Page 40: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/40.jpg)
Jacquard loom
![Page 41: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/41.jpg)
Long-term impact
Jacquard loom was quickly adoptedReduced manpower needs for weaving of
fabrics with complex patterns Caused a workers' revolt in Lyon in 1831
Still in use today Showed that information could be stored in a
machine-readable form
![Page 42: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/42.jpg)
Charles Babbage
English mathematician and mechanical engineer
Proposed a mechanical calculator that could tabulate polynomial functions Not built until much later
![Page 43: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/43.jpg)
Motivation
Polynomials were used—and are still used—to compute logarithms, sines, cosines and so onBoole wanted to speed up the computation of
numerical tables
![Page 44: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/44.jpg)
The differential engine
![Page 45: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/45.jpg)
Long-term impact
Boole went on to design a much more ambitious analytical enginePrototype of a modern computer
Some difference engines were built laterOne was used to produce printed logarithmic
tables Showed that computations can be programmed
![Page 46: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/46.jpg)
Samuel Morse
American painter and inventor Invented the telegraph
First practical application of electricity
"Queen Victoria's Internet" Huge immediate impact on
many human endeavorsMade the world smaller
![Page 47: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/47.jpg)
Long-term impact
Was developed to avoid continued fighting after peace treaty (Treaty of Ghent 1814)Did not guarantee universal peace among
nations Showed that information could travel fast over
long distances
![Page 48: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/48.jpg)
Herman Hollerith
American statistician Tried to speed up
the processing of the 1890 census
Invented the tabulating machine
![Page 49: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/49.jpg)
Tabulating machine and sorter
![Page 50: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/50.jpg)
How they worked (I) Used punched cards
Hollerith cardsBecame obsolete in the late seventies
![Page 51: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/51.jpg)
How they worked (II)
When tabulating machine read a card, it couldAdd the values stored in some columns to
one of its registers Instruct the sorter to open one of its slots
Next step was to make cards move within tabulator and sorter without any human intervention
![Page 52: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/52.jpg)
Long-term impact
Tabulating machines were produced until the mid-seventiesWere used all around the worldMade IBM
While Babbage’s differential engine was purely mechanical, Hollerith tabulating machines were electromechanical.
![Page 53: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/53.jpg)
More inventors (I)
Charles Sanders PierceAmerican philosopher, logician and inventorShowed in 1880’s that Boolean algebra could
be implemented by electrical circuits
![Page 54: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/54.jpg)
Boolean algebra
Uses two quantities (0 or 1; true or false) Basic operations include
AND:p AND q is true iff both p and q are true
OR:p OR q is true unless both p and q are false
NOT:NOT p is true if p is false and false otherwise
![Page 55: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/55.jpg)
Boolean algebra and circuits
Convention:Switch on is 1, switch off is zero
AND:
OR:
![Page 56: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/56.jpg)
More inventors (II)
John Atanasoff and Clifford Berry Iowa State CollegeBuilt a very limited computer using vacuum
tubes in the 1930’s
![Page 57: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/57.jpg)
World War II
United States had to build very quickly large armed forcesTrain and equip them
Needed better ballistic tables to predict naval gun trajectoriesResulted in development of two computers
![Page 58: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/58.jpg)
Harvard Mark I
Designed by Howard H. Aiken Built by IBM from switches, relays and other
electromechanical parts First programmable computer
Read its instructions from a punched paper tapeExecuted them in sequenceLoops were implemented by making a paper loop
![Page 59: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/59.jpg)
ENIAC
Electronic Numerical Integrator And Computer Designed and built at University of Pennsylvania
by a team headed by John Mauchly and J. Presper Eckert
Used vacuum tubesThousand times faster than Harvard Mark I
Came too late to contribute to war effort Needed to be programmed externally
![Page 60: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/60.jpg)
EDVAC
Successor to ENIAC Designed by same authors Used binary arithmetic
Simpler Stored its programs in its memory
Could even modify them while running
(Von Neumann architecture)
![Page 61: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/61.jpg)
Other WW II Computers
Set of top secret machines developed in UK to crack German Enigma code
Collectively known as Colossus
Existence was not known until much later
![Page 62: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/62.jpg)
Binary arithmetic
Used by all computers Two-digit arithmetic
0 and 1Easier to implement
Two voltages HIGH and LOW
![Page 63: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/63.jpg)
Binary numbers
0 same as decimal 0 1 same as decimal 1 10 same as decimal 2 11 same as decimal 3 100 same as decimal 4 1K = 1 followed by ten zeroes, same as 1,02410
1M = 1 followed by twenty zeroes a million 1G = 1 followed by thirty zeroes a billion
![Page 64: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/64.jpg)
Deciphering decimal numbers
Both digit value and position count937
Rightmost value indicates units Value at its left indicates tens Leftmost value indicates hundreds
We read 937 as nine hundred thirty-seven
![Page 65: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/65.jpg)
Deciphering binary numbers
Both digit value and position count110
Rightmost value indicates units Value at its left should be multiplied by 2 Leftmost value should be multiplied by 4
We read 110 as 0×1 + 1×2 + 1×4 = 6
![Page 66: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/66.jpg)
Binary addition and multiplication
0 + 0 = 00 + 1 = 11 + 0 = 11 + 1 = 10
0 × 0 = 00 × 1 = 01 × 0 = 01 × 1 = 1
![Page 67: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/67.jpg)
The Von Neumann architecture
Input Output Memory containing program and data Processor
DatapathControl
Storage subsystem came later
![Page 68: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/68.jpg)
A single bus realization
![Page 69: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/69.jpg)
A more recent realization Northbridge chip is
much faster than Southbridge chip
Trend is to include the functionality of the Northbridge in the CPU chip Intel Sandy Bridge AMD Fusion
![Page 70: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/70.jpg)
A laptop motherboard
![Page 71: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/71.jpg)
THE FIRST GENERATION
Used vacuum tubesWere power hungry and unreliable
UNIVACFirst commercially successful computer
IBMWell established tabulating machine maker Started dominating the field in the mid to
late fifties
![Page 72: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/72.jpg)
The UNIVAC I
![Page 73: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/73.jpg)
Overall organization
Quite similar to that of today’s computers
CPUMAIN MEMORYprograms + data
PERIPHERALS
![Page 74: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/74.jpg)
Evolution
Revolution was started by UNIVAC IBM quickly become the leader
Was a true computer companyWell introduced in most businesses
Already used IBM tabulating machines In the sixties and seventies, most people
identified IBM as “the” computer maker
![Page 75: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/75.jpg)
Batch systems
Allow users to submit a batches of requests to be processed in sequence
Include a command language specifying what to do with the inputsCompile Link editExecute and so forth
![Page 76: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/76.jpg)
An IBM 1401
![Page 77: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/77.jpg)
Interactive systems
Came later Allow users to interact with the OS through their
terminals: Include an interactive command language
UNIX shells, Windows PowerShellCan also be used to write scripts
![Page 78: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/78.jpg)
Time sharing (I)
Lets several interactive users to access a single computer at the same time
Standard solution when computers were expensive
![Page 79: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/79.jpg)
Time sharing (II)
![Page 80: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/80.jpg)
UNIX (I)
Started at Bell Labs in the early 70's as an attempt to build a sophisticated time-sharing system on a very small minicomputer.
First OS to be almost entirely written in C Ported to the VAX architecture in the late 70’s
at U. C. Berkeley: Added virtual memory and networking
![Page 81: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/81.jpg)
The fathers of UNIX
Ken Thompson and Denis Ritchie
![Page 82: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/82.jpg)
UNIX (II)
Became the standard operating systems for workstations
Selected by Sun Microsystems Became less popular because
Two many variants Berkeley BSD, ATT System V, …
PCs displaced workstations Windows has a better user interface
![Page 83: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/83.jpg)
UNIX Today
Several free versions exist (FreeBSD, Linux): Source code of these free versions is
available at no cost Ideal platform for OS research
UNIX/Linux-based kernels used by Apple OS X and iOS operating system Android operating systems Chrome OS is barely modified Linux
![Page 84: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/84.jpg)
Time sharing (III)
Time sharing become much less important by the end of the eightiesPersonal computers became almost as cheap
as terminalsTime sharing could not support graphical user
interfaces
![Page 85: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/85.jpg)
Why?
A graphical user interface must transfer a lot of data between the processor and the display unitCannot do it if distance exceeds a few feet
The workstation was bornCombines a computer with its display
![Page 86: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/86.jpg)
Graphical user interfaces
Called GUIs (pronounced goo-eys): Macintosh, Windows, X-Windows, Linux
Require a dedicated computer for each user Pioneered at XEROX Palo Alto Research Center Popularized by the Macintosh Dominated the market with Microsoft Windows
![Page 87: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/87.jpg)
Xerox PARC (I)
Founded by XEROX in 1970 Invented
Laser printing Ethernet The GUI paradigm Object-oriented programming (Smalltalk)
![Page 88: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/88.jpg)
Xerox PARC (II)
All their inventions were brought to market by other concerns
Popular belief is that Xerox management blew it In reality
Alto workstations were very expensiveSmalltalk was very slowGroup was too small to deliver a full system
![Page 89: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/89.jpg)
The personal computer
By 1971, it was possible to put a very simple CPU on a single chip Intel 4004 was a four-bit microprocessor
designed for a desktop calculatorFollowed by an 8-bit version 8008
Used to build very basic personal computers
![Page 90: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/90.jpg)
Evolution (I)
1977: Apple ][First widely successful mass-produced PCKiller app was Visicalc spreadsheet
1981: IBM PCBig success because people trusted IBMMicrosoft designed the OS (PC-DOS)
![Page 91: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/91.jpg)
Evolution (II)
1984: MacintoshFirst mass-produced PC with GUIWas not an instant successRescued by laser printer
1992: Windows 3.1MSDOS + Windows 3.1 offered the first GUI
solution for IBM PCs
![Page 92: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/92.jpg)
How IBM lost the PC market (I)
IBM PC used “off-the-shelf” components Microsoft retained the rights to sell PC-DOS
to other computer makers (MS-DOS) Sole specific part was BIOS
Very basic operating system stored in read-only memory
Loads MS-DOS/Windows in main memory© IBM
![Page 93: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/93.jpg)
How IBM lost the PC market (II)
Chip makers learned to produce functionally equivalent BIOS without violating IBM copyrightReverse engineering:
Define IBM BIOS by all its outputs for all possible inputs
Hire people who had never seen the IBM BIOS to rewrite it
![Page 94: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/94.jpg)
How IBM lost the PC market (III)
Rivals could sell PCs at cheaper prices than IBMLeaner cost structure
Could come with new models faster than IBM didLess cumbersome review process
![Page 95: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/95.jpg)
The new frontiers
Smaller devices:Now-defunct PDAs, smart phones, tabletsCheaper than PCs (but tablets)Much bigger market
New microprocessor architectures: Intel—and AMD—pulverized the competition
(Motorola 68000, MIPS, PowerPC, Sun SPARC)
Now competing with ARM chips
![Page 96: COSC 1306 COMPUTER SCIENCE AND PROGRAMMING Jehan-François Pâris jfparis@uh.edu](https://reader035.vdocuments.us/reader035/viewer/2022062715/56649daa5503460f94a98164/html5/thumbnails/96.jpg)
Challenges
Openness
Digital divide
Addiction