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Please switch off your mobile phones

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Prolog: The InitiationET: 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?

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WELCOME To ESC101N:Fundamentals of Computing

Instructor: Mainak Chaudhurimainakc@cse.iitk.ac.in

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Agenda

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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)

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“The Computing Stack”Problem

AlgorithmProgram (HLLs)

HLL Compiler/LinkerExecutable binaryOperating SystemMicroarchitecture

CircuitsTransistors

ESC101NHLL=Java

Central in CS

Hardware/softwareinterface

Hardware

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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