CS125 Homework 0000 Page ��� of ��� Netid: _ _ _ _ _ _ _ @ illinois.edu 1 2

Bring your PRINTED answers to next week’s lab section.

Q 000002 Alice encodes each symbol in her message using dots and dashes (“Zeros and Ones”). To prevent Eve from eavesdropping she encrypts her message by swapping a zero for a one and vice versa. Explain why this is an insecure encryption scheme.

Q 00001 Alice chooses a code that always uses N dots and dashes to encode each symbol. How many different symbols could be represented with N=4 dots and dashes? What if she chooses 8 ? 10? 16?

4bits: 8bits: 10bits: 16bits:

Q 00010 An audio signal can be encoded at 44100 samples per second. Each sample is encoded using 16 bits. How many bits does a CD need to store for 1 hour of stereo (2 track) uncompressed audio?

Q 00011 Why is it possible to compress audio and video data and store & transmit the same song using much less space?

Text Q 00100 What is ASCII?

Q 00101 How many bits does ASCII use to represent each character?

Q 00110 What is the ASCII code for space? tab? ‘A’? Write a character that ASCII cannot be represent

Space: tab: A: No-code:

Q 00111 What is Unicode and why was it invented?

CS125 Homework 0000 Page ��� of ��� Netid: _ _ _ _ _ _ _ @ illinois.edu 2 2

History & Illinois

Q 01000 Who is Ada Lovelace. Why is she considered the first programmer?

Q 01001 What was Illinois’s Plato system? What features did it include?

Q 01010 Why is Alan Turing important to Computer Science?

Q 01011 How is the von Neumann Architecture different from the Harvard architecture?

Q 01100 Which University built and owned the first computer using on the von Neumann Architecture in 1952? What was the name of the Machine?

Univ: Machine Name:

Q 01101 What are the names of your TA and undergrad course assistants?

Q 01110 Who is Gordon Moore and what is his law?

Q 01111 Which university has the largest ACM membership on the planet? How many ACM SIGs are there at UIUC? Which one(s) interest you the most?

Q 10000 What is a CPU register?

Q 10001 What is the name of the UIUC student organization dedicated to iOS programming?