Please switch off your mobile phones

Please switch off your mobile phones

Prolog: The Initiation ET: Hey Alice! What is this on your desk? Alice: That’s a digital computer. ET: Digital what? Looks pretty unsocial. Doesn’t even greet me! Alice: It helped us discover you and your solar system. ET: Wow! That sounds cool. How do you use it? Does it talk? Alice: It can solve hard problems. You have to program it to do that. ET: Will you teach me do that?

WELCOME To ESC101N:Fundamentals of Computing Instructor: Mainak Chaudhuri mainakc@cse.iitk.ac.in

Agenda • Administrivia • What this course is not about • Anatomy of a computer

Administrivia • Lecture hours • Monday, Wednesday, Thursday: 9-10am, L17 • Please come to class in time • Labs • 2pm-5pm, 11 lab sessions • Monday: B5-B6, Tuesday: B1-B2, Wednesday: B9-B10, Thursday: B7-B8, Friday: B3-B4 • No lab this week • Tutorial • Tuesday 9-10am, Tutorial Block 101-110 • No tutorial this week

Administrivia • Grading [this is the sad part] • Exam: 15+15+30 • One compulsory lab test: 10 • Project or another lab test (your choice): 20 • Weekly lab sessions: 10 • Two surprise quizzes: 10 (this is extra) • Held in tutorial sessions • No make up for surprise quizzes (so come to tutorial regularly) • Project proposal submission deadline: any time before 1st October • Can get started even today if you know Java

Administrivia • There will be a course web page with all info • Temporarily: www.cse.iitk.ac.in/~mainakc/esc101notes.html • Text book • Nothing specific: your choice • Suggestion: “Java Elements: Principles of Programming in Java” by Bailey and Bailey • More references are on the webpage • Visit past course sites: www.iitk.ac.in/esc101

For Visitors and Wanderers • Also known as audit students • In case you want to experience the “excitements” of the tutorials and labs • Send your section preference to me so that we can be prepared to accommodate you • But not allowed to sit in the lab tests • Can do a project, but will not be graded • Can write quizzes, but will not be graded • Not allowed to take the exams • In case there are too many visitors, we will not allow anyone in the tutorials and labs

What this course is not about • This is not a course on programming • You will learn how to solve problems with computers: especially the ones that you cannot solve with paper and pencil quickly • The greater part of the lectures will be devoted to the concepts involved in developing a computer algorithm • Sequence of steps that solve a problem • Java will be used as a vehicle to demonstrate the concepts • Do not expect to become an expert in Java after taking this course

Anatomy of a computer • What you see • A monitor, a keyboard, a mouse, a printer … • Input/Output devices • Through these you ask the computer to do something and the computer tells you the results • Need a way to convey your commands to the computer (it is really a stupid device which cannot do anything on its own) • Internally • A central processing unit and a scratchpad (often called main memory) accomplish the job

Anatomy of a computer • Central processing unit does not understand English, not even Java • It only understands two symbols: 0 and 1 • These are called bits (short for binary digits) • You encode your algorithm into a high-level language called Java • This is called a program • This is harder to understand than English, but easier to understand than a 0-1 encoding • How do I encode a program in 0-1? This is used only for storing the program in main memory

Anatomy of a computer • A friend of yours called compiler translates the program into a binary encoding called an object program • This is almost understandable to the central processing unit (often called a microprocessor) • Another friend of yours called a linker adds something more to an object program to convert it to an executable • This is understandable to the CPU • But somehow it needs to get started executing

Anatomy of a computer • A big boss called operating system loads the executable in main memory and hands over the control to the CPU • Now the CPU starts executing your program (essentially the binary executable) • Once in a while it prints something on the monitor and you appreciate that • Notice that it is not doing anything on its own, only doing whatever you have asked it to do • At some point the CPU completes the execution and you have all the results

A simple program • Let’s write a program in English (almost) • Want to add five numbers a, b, c, d, e and print the result on monitor print (monitor, a+b+c+d+e) • print is used as a function which takes two arguments: where to print and what to print • A binary translation of this could convert each character i.e. p, r, i, n, t, (, m, … into a binary string e.g., p is the 16th alphabet, so represent it as 16 zeros; put a 1 to mark the end of a character • Now I can design a CPU which can understand this translation and execute my program (caution: this is just an example)

“The Computing Stack” ESC101N HLL=Java Central in CS Problem Algorithm Program (HLLs) HLL Compiler/Linker Executable binary Operating System Microarchitecture Circuits Transistors Hardware/ software interface Hardware

Next week’s lab • Learn to use the UNIX environment • How to create a file (this is where you store your programs) • How to create and navigate through directory (this is where you store your files) • How to copy files from one directory to another • And more: www.iitk.ac.in/esc101/linux.pdf • Lab is upstairs in CC: TAs will be present at the front door to lead you

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