1. CS 201 Introduction to Computing
SPRING 2017

2. This course will give you
Basic computer science notions
Mostly C++ programming concepts
with emphasis on computational problems
Object Oriented Programming language
At the end of this course, you will be able to
develop algorithms
write programs using C++
but not-so-big-applications

3. Course Information CS201 – Introduction to Computing
Website
also follow SUCourse
an list will be set up for announcements
so you are responsible to check your s (sabanciuniv account)
Instructor:
Gülşen Demiröz, FENS L015,
Textbook: A Computer Science Tapestry, by Owen Astrachan – several copies in the library
Weekly or Biweekly Homework Assignments

4. Course Information Lecture Schedule (in FENS G077):
Monday 13: :30
Tuesday 15: :30
Recitations will start first week
See your schedule for date, time and location
Recitations will also be used as labs, so please take your laptops with power cables to recitations
Freshmans could not register yet.
Ask for Special Approval to the recitation:
Go to the recitation section that you will add.
Attend all. It is to your benefit. Recitation Attendance: %4 of your grade.

5. Course Policy Grading (might change)
Two Midterm Exams + One Final Exam
Midterm 1 (23%): March 27th Monday 19:40 – 21:30
Midterm 2 (23%): May 2nd Tuesday 19:40 – 21:30
Final Exam (30% ): scheduled by registrar
Recitation Attendance (%4): %1 is left to the TA as “kanaat”
Homeworks (20% total): 7 homework will be assigned and they are not of equal weight
Important Notice about grading:
Weighted average is not the only criterion in letter grading; exam average compared to homework average will also be taken into consideration.

6. Course Policy No late homework without penalty
One late day is allowed at cost of 10% of full grade
Plagiarism is not tolerated
All homeworks have to be personal.
We use tools to detect plagiarized homework.
Cooperation is not an excuse
If you do not know how to cooperate, don’t do it
Grades will be divided into the number of people who cooperated.
First case –100 (minus hundred), second fails the course!
Detailed policy is on the web site of the course

7. Course Policy Make-ups (detailed policy is on the web)
reports must come before or during the exam
you must be really sick to take a make-up exam
according to the by-laws, acceptance of report is up to the instructor
a medical report does not guarantee taking a make-up exam
make-ups will be much more harder

8. Before CS 201 Maybe you are afraid of computers Maybe you hate
How do you use computers.
Maybe you used computers just for fun before

9. During CS 201 You may have bad dreams at the beginning
And you may think of you are going nuts
But if you work properly and spend considerable amount of time ...
Be patient.

10. At the End of CS 201
Success is yours!

11. The Burning Question
What is Computer Science and Engineering? 10

12. The Burning Question What is Computer Science and Engineering?
What is Science?
Science is the study and understanding of the possible (and beyond.)
Science is mainly analytic, that is,
it tries to analyze, understand and describe nature
Observe, hypothesize, predict, evaluate, and refine 11

13. The Burning Question What is Computer Science and Engineering?
What is Engineering?
Engineering is the study of the feasible, that is, what is possible within time, space and money constraints.
Engineering aims to synthesize the artificial, but, one should have very good analytical skills, also! 12

14. What is Computer Science?
Computer science is the study and the science of the theoretical foundations of information and computation and their implementation and application in computer systems.
Information – data
Computation – processing, problem solving
A computer is a machine that manipulates data according to a list of instructions.
The discipline is called informatics in many countries
especially in Europe

15. History of Computer Science
Computer Science is a relatively young discipline
More than 50 years
First graduate program at CMU (then Carnegie Tech) in 1965
in Turkey first CS department in 1977
Turing machine (1937)
abstract machine
theoretically capable of any computation that we can do with modern computers today

16. Alan Turing (1912--1954) A scientist and mathematician
Watch the movie The Imitation Game
Instrumental in breaking a German coding machine during WW II
Developed mathematical model of a computer called a Turing Machine (before computers)
Showed there are problems that cannot be solved by a computer
Was a long distance runner
committed suicide

17. What is Computer Engineering?
An engineering discipline for building hardware and software systems that
store
transmit
process
information. 16

18. What do Computer Engineers do?
They build systems that process information.
They do research into how to build systems:
that are new (incorporating new ideas and technology),
that solve an important problem unsolved satisfactorily
that are “cheap” (so that they are affordable) 17

19. Building Systems
Computer Engineers build information processing systems by bringing together
hardware
software
so that the system
works, i.e. has (almost) no bugs
is fast, maintainable, robust, and affordable. 18

20. Computer Science & Engineering
Computer Science & Engineering is more than programming!!!
Hardware Engineering developing hardware products
Software Engineering developing software products
Operating Systems Windows, Linux/UNIX, MacOS
Graphics animation, entertainment, games
Computer Security hacking, digital signatures
Computer Networking made internet a reality
Artificial Intelligence thinking machines, learning
Scientific Computing biocomputing
Theoretical CS analyze algorithms
…….

21. Problems, Algorithms, and Programs
Problem: A situation that needs to be dealt with
Algorithm: Computational procedure for solving a problem.
Program: Implementation of an algorithm using a specific programming language to execute on specific platforms
Problem
Algorithm
Program

22. Problem In general: a situation that needs to be dealt with
Some problems:
Finding the best phone to buy
Tiding up your books so that you can find what you want easier
Going from SU Campus to Taksim Square
Problems defined more precisely:
Finding the cheapest phone to buy
Putting your books in alphabetical order so that you can find what you want easier
Going from SU Campus to Taksim Square by using a car not having an OGS/HGS
I would spend 55 minutes defining the problem and then 5 minutes solving it.
-- Albert Einstein

23. Problem
In CS: a situation that needs to be dealt with, by a using computer
Some problems in CS:
Finding the smallest number in a given set (Finding the cheapest phone to buy)
Sorting a given set of items (Putting your books in alphabetical order)
Finding a path in a graph
(Going from SU Campus to Taksim Square by using a car not having an OGS/HGS)

24. Algorithms Arabic-originated word
Step-by-step process that solves a problem
do this, then do that, ...
eventually stops with an answer
general process rather than specific to a programming language

25. Algorithms Example algorithms to solve a problem
An example algorithm to go from SU Campus to Taksim:
Turn right after leaving the campus
Drive 2-3km and turn left …
A more precise algorithm to go from SU Campus to Taksim:
Drive 2512 meters and turn left

26. Example Algorithms – Find The Heaviest BallC
3 seemingly identical steel balls
A two arm balance scale

27. Example Algorithm - Find the minimum
Initial list:
Should we sort?
About (n.log(n)) operations, where n is the number of elements
Optimal algorithm - About n operations
Pick 4 as the minimum
Compare 4 to 6 - min is still 4
Compare 4 to 7- min is still 4
Compare 4 to 3 - Pick 3 as the minimum
Compare 3 to 9- min is still 3
Compare 3 to 1 - Pick 1 as the minimum
Compare 1 to 4- min is still 1
Compare 1 to 5 - We are done and the minimum is 1

28. Algorithms Issues correctness complexity and efficiency
I picked a number between 1 and 100
You will guess it
I’ll respond “high”, “low”, “correct”.
how many guesses needed (worst case)?

29. Programs A program is an implementation of an algorithm
using a specific programming language
to execute on specific platforms
Programming language are needed, because natural languages are
vague
ambiguous
hard to reason about

30. Programming Languages
A programming language is a formal constructed language to communicate instructions to a machine, particularly to a computer
High-level programming languages
C++, Java, C, C#, Perl, Fortran, Lisp, Scheme, Visual BASIC, ...
Low-level programming languages
Assembly language

31. High-Level vs. Low-Level Languages
Rather than instruct computers at the level of 0’s and 1’s, higher level languages have been developed.
Flexible and easier programming

32. High-Level vs. Low-Level Languages
int main() {
int x, y, z;
x = 7;
y = 12;
z = x * y;
return 0; }
main:
pushl %ebp
movl %esp,%ebp
subl $12,%esp
movl $7,-4(%ebp)
movl $12,-8(%ebp)
movl -4(%ebp),%eax
imull -8(%ebp),%eax
movl %eax,-12(%ebp)
xorl %eax,%eax
jmp .L1
.align 4
compiler
assembler
high-level
low-level (assembly)
lowest-level (binary)

33. Compilers
Translate a high level language, such as C++, into machine-specific executable program (0s and 1s)
The compiler is a program, input is C++ program, output is an executable binary program
In theory, C++ source code works on any machine given a compiler for the machine
for other languages different compilers are needed

34. Levels of Programming Language - assembly
Machine specific assembly language, Sparc on left, Pentium on right, both generated from the same C++ code
main: main:
save %sp,-128,%sp pushl %ebp
mov 7,%o movl %esp,%ebp
st %o0,[%fp-20] subl $12,%esp
mov 12,%o movl $7,-4(%ebp)
st %o0,[%fp-24] movl $12,-8(%ebp)
ld [%fp-20],%o movl -4(%ebp),%eax
ld [%fp-24],%o imull -8(%ebp),%eax
call .umul, movl %eax,-12(%ebp)
nop xorl %eax,%eax
st %o0,[%fp-28] jmp .L1
mov 0,%i align 4
b .LL xorl %eax,%eax
nop jmp .L1

35. Data Representation in Computers
All types of data are represented in numeric format
characters – ASCII (Unicode) codes
‘+’ = 43, ‘A’=65, 'C’=67, ‘Z’=90
colors – RGB values
Music files, such as .mp3 files, and video files, such as .mov files are also represented in numbers
s, tweets, facebook messages
Low-level machine instructions
And everything else

36. Data Representation in Computers
Internal representation (at the lowest level) is in binary form, i.e., in base-2 numeral system
0s and 1s
all arithmetic in binary too
Examples
410 = 1002
510 = 1012
6710=
4310=

37. Representation vs. Interpretation
Programs instruct computers on how to interpret these binary numbers
For Example can be interpreted as
As string ‘C++’
As RGB color C +
red
green
blue

38. A Simple Scenario Problem Algorithm Program
Given 3 numbers, compute their sum
Algorithm
Display a prompt for data entry
Input 3 numbers: number1, number2, number3
sum  number1 + number2 + number3
Output sum
Program
First, we will write a C++ program and run it using MS Visual Studio (sum3num.cpp)
Then we will see an animation about the steps taken during the execution

39. MS Visual Studio .NET (2012) One way of developing C++ programs
You will install to your laptops
Help will be available in first week labs
Check website for instructions on how to install, if you prefer to install before the labs
You can install
over the network
\\software\microsoft\VisualStudio\Visual_Studio_2012
step-by-step installation screenshots are on course web site

40. A Simple Program – Execution steps

41. Central Processing Unit
COMPUTERS
Central Processing Unit
(CPU)
executes primitive instructions

42. COMPUTERS Central Processing Unit Random Access Memory (CPU) (RAM)
executes primitive instructions
Random Access Memory
(RAM)
stores instructions & data

43. Memory Primary memory is generally RAM fast data access volatile
electricity gone, data gone
expensive
Secondary memory (storage)
Disks, tapes, CD-ROMs, floppies, flash memory
non-volatile
slow data access
cheap
ROM (Read-only memory)
BIOS (Basic Input Output System) - to start the system (before the operating system)

44. COMPUTERS Central Processing Unit Random Access Memory (CPU) (RAM)
motherboard
… bunch of other hardware …
Central Processing Unit
(CPU)
executes primitive instructions
Random Access Memory
(RAM)
stores instructions & data
bus
instructions & data

45. COMPUTERS Central Processing Unit Random Access Memory (CPU) (RAM)
executes primitive instructions
Random Access Memory
(RAM)
stores instructions & data
instructions & data
bus
keyboard
mouse
monitor
printer
hard disk
CD-ROM
input devices
provide instructions and
data to the system
output devices
return data from the system
input/output (IO) devices
are input and output devices at
the same time

46. A Typical Computer System

47. A Motherboard

48. Important Parameters CPU Speed: Hz, MHz(106 Hz), GHz (109 Hz ), etc.
Memory Capacity: Megabytes, Gigabytes, etc.
Central Processing Unit
(CPU)
executes primitive instructions
Random Access Memory
(RAM)
stores instructions & data 46

49. How Much Memory Is That? Bit A basic unit of information storage
Stores a binary decision yes/no, or 0/1  47

50. How Much Memory Is That? Byte 8 bits 1 byte: One character
140 bytes: Longest possible tweet (under certain assumptions) 48

51. How Much Memory Is That? Kilobyte
1,024 bytes; 210; approx. 1,000 or 103
1 Kilobyte: Joke; (very) short story
2 Kilobytes: Typewritten page
10 Kilobytes: Page out of an encyclopedia
50 Kilobytes: Image of a document page, compressed
100 Kilobytes: Photograph, low-resolution
200 Kilobytes: Two boxes (4000) punched computer (Hollerith) cards
500 Kilobytes: Five boxes, one case (10,000 of punched computer (Hollerith) cards 49

52. How Much Memory Is That? Megabyte
1,048,576 bytes; 220; approx 1,000,000 or 106
1 Megabyte: Small novel; 3-1/2 inch diskette
2 Megabytes: Photograph, high resolution
5 Megabytes: Complete works of Shakespeare; 30 seconds of broadcast-quality video
10 Megabytes: Minute of high-fidelity sound; digital chest X-ray; Box of 3-1/2 inch diskettes
20 Megabytes: Two boxes of 3-1/2 inch diskettes
50 Megabytes: Digital mammogram
100 Megabytes: Meter of books on a shelf; two encyclopedia volumes
700 Megabytes: CD-ROM 50

53. How Much Memory Is That?
Gigabyte    1,073,741,824 bytes; 230; approx 1,000,000,000 or 109
1 Gigabyte: Paper in the bed of a pickup; symphony in high-fidelity sound; broadcast quality movie
2 Gigabytes: 20 meters of books on a shelf
20 Gigabytes: Audio collection of the works of Beethoven; VHS tape used to store digital data
50 Gigabytes: Library floor of books on shelves 51

54. How Much Memory Is That?
Terabyte      1,099,511,627,776 or 240;      approx. 1,000,000,000,000 or 1012
1 Terabyte: All the X-ray films in a large technological hospital; 50,000 trees made into paper and printed;
2 Terabytes: Academic research library
10 Terabytes: Printed collection of the U. S. Library of Congress
50 Terabytes: Contents of a large mass storage system (Google uses many many of these) 52

55. How Much Memory Is That?
Petabyte      1,125,899,906,842,624 bytes or 250      approx. 1,000,000,000,000,000 or 1015
2 Petabytes: All U. S. academic research libraries
20 Petabytes: 1995 production ALL hard-disk drives
200 Petabytes: All printed material; 53

56. Petabyte Memory
What would YOU store if you had a petabyte disk in your laptop? 54

57. Petabyte Memory
What would YOU store if you had a petabyte disk in your laptop?
Everything your eyes see
Everything you hear/say 55

58. How Much Memory Is That?
Exabyte      1,152,921,504,606,846,976 bytes or 260      approx. 1,000,000,000,000,000,000 or 1018  
5 Exabytes: All words ever spoken by human beings. 56

59. How Much Memory Is That?
Exabyte      1,152,921,504,606,846,976 bytes or 260      approx. 1,000,000,000,000,000,000 or 1018  
5 Exabytes: All words ever spoken by human beings.
Not very clear you would want that in your laptop!
Source: How Much Data is That? 57

60. A Little bit of History
Where are we coming from?

61. First Generation ( )

62. First Generation ( )
1950’s hard drive

63. Punched Cards
Punched Card Input? What Is that?

64. Punched Cards
Punched Card Input? What Is that?

65. Punch Machines 63

66. Punched Cards
Input with punch cards 64

67. Second Generation (1959-1965) 1960’s 100 KHz Machines (IBM 1620)
20-30 KB Memory
Punched Card Input
Teletypes and Line Printers
10-20 MB Disks
Consume kilowatts, needs AC cooling
ARPANET starts about here also
Magnetic disks

68. Third Generation (1965 - 1971) Integrated circuits
Keyboard and monitor
Transistors for memory construction 66

69. Forth Generation (1971 - ?) Large scale integrated circuits
The phrase “personal computer” (PC) was coined
Apple, Tandy/Radio Shack, Atari, Commodore, Sun, … 67

70. Very Large Scale Integrated Circuit Technology
Xbox One SoC, 2013
5 trillion transistors
853 MHz
768 cores
Sparc M7, 2014
More than 10 trillion transistors
3.x GHz: More than 600 times that of 8086
32 cores
9mm
12mm

71. Historical Perspective
Wireless networks take off (3G, IEEE , Bluetooth, Wi- Max)
Broadband reaches households
Mobile computing
Convergence of hand-held devices (telephone, PDA, Mp3 player, radio, camera)
Convergence of home information and entertainment appliances (PC, TV, DVD & CD players) 69

72. Historical Perspective
2010+:
Cars, appliances, telephones, everything have some computing power somewhere,
High network bandwidth (and wireless too),
Speech and visual interfaces, ubiquitous computing, and gods knows what else.
Wearable computers 70

73. Moore’s “Law” Transistors double every 18-24 months
Memory capacity doubles every months

74. Moore’s Law 72

75. Where we are heading? Single CPU Multiple Users 1 CPU per Person
Many CPUs
per Person 74

76. COMPUTER SYSTEMS
The Onion Skin Analogy
Hardware 75

77. COMPUTER SYSTEMS The Onion Skin Analogy
Operating System (XP, Linux, etc)
Hardware 76

78. COMPUTER SYSTEMS The Onion Skin Analogy Application Support
(Window Managers, Graphics, User Interfaces, Development Env.)
Operating System (XP, Linux, etc)
Hardware 77

79. COMPUTER SYSTEMS The Onion Skin Analogy Application Support
Applications (Word, Firefox, iTunes)
Application Support
(Window Managers, Graphics, User Interfaces, Development Env.)
Operating System (XP, Linux, etc)
Hardware 78

80. COMPUTER SYSTEMS Structural Complexity
Hardware – Several trillion transistors
Software – 10’s of millions of lines of code
Windows XP: 45 millions of lines of source code
Premium-class automobile: 100 millions of lines of code
So developing a computer system is a VERY, VERY COMPLEX affair.

81. COMPUTER SYSTEMS
Managing this complexity is THE MAJOR PROBLEM in building computer systems.
So, such (software) systems are also built in again a hierarchical fashion like the onion-skin analogy.
Rather similar to building something with a Lego kit.

82. COMPUTER SYSTEMS We have small pieces that have
certain functionality
and
interface
how they “fit” with others
We put them together to achieve a goal
The interfaces have to fit
The final functionality is what we want

83. First Program Problem Algorithm Program
How many 3-digit positive numbers are there that are divisible by 7, but not divisible by 4?
Algorithm
Try all 3-digit numbers between 100 and 999
If a number is divisible by 7 but not by 4,
increment a counter
Display the value of the counter
Program
myfirstprogram.cpp