Welcome to Comp 411!

Whos and Whats...

Lectures:		Leonard McMillan (SN-311) Office Hours Mon 2-4
TA:		TBD Office Hours TBD
Book:	None this semester.	We'll use only my notes.

Course Mechanics

Grading:

Best 5 of 6 problem sets	25%
Best 9 of 10 problem sets	20%
2 in-class exams	30%
Final exam	25%

You will have at least two weeks to complete each problem set. Problem sets will be online. Late problem sets will not be accepted, but the lowest problem-set score will be dropped.

Friday Labs are mandatory, and will meet on most Fridays, grade is based on completing a "lab check list."

I will attempt to make Lecture Notes, Problem Sets, and other course materials available on the web before class on the day they are given.

Course Website

Goals of Comp411

To answer fundamental questions

Goal 1: To Demystify Computers

Strangely, most people (even some computer scientists I know) are afraid of computers.

We only fear what we do not understand!

I do not fear computers. I fear the lack of them.
- Isaac Asimov (1920-1992)

Fear is the main source of superstition, and one of the main sources of cruelty. To conquer fear is the beginning of wisdom.
- Bertrand Russell (1872-1970)

Goal 2: The Power of Abstraction

Define a function, develop a robust implementation, and then put a box around it.

Abstraction enables us to create unfathomable systems (including computer hardware and software).

Why do we need ABSTRACTION?

Imagine a billion --- 1,000,000,000

Goal 3: Managing a Billion Parts

What does a program do?

int f(x) {
    int r;
    int odd = 1;
    for (r = 0; x >= odd; r++) {
        x -= odd;
        odd += 2;
    }
    return r;
}
    

How does a computer do?

int f(x) {
    int r;
    int odd = 1;
    for (r = 0; x >= odd; r++) {
        x -= odd;
        odd += 2;
    }
    return r;
}
    

Are there limits of computation?

• Will there be new instructions that fundamentally change how fast computers work?
• Can computers solve any well specified problem?
• Can we predict how long it will take for a computer to solve a problem?
• Does there exist a new model of computation?

A simple computer model

    int memory[16384];    // for instuctions and data
    int register[32];     // for variables
    int pc;               // next instruction to execute
    int flags;

    void main(void) {
        pc = 0;
        while (1) {
            instruction = memory[pc];
            pc = pc + 1;
            flags = execute(instruction);
        }
    }
    

A computer is an interpreter that executes a simple program loop.

Where are we going?

• How is data represented, stored, and manipulated in a computer?
• What basic operations does a computer use?
• What does mean to "compute"?
• Are there limits to what can be computed?
• Why are computers so fast?
• What am I asking a computer to do when I give it a program to execute?
• How are programs translated into computer instructions?
• Why are some programs faster than others that perform the same function?

Summary

411 answers the following questions:

411 Logistics: