Class 22: Homework 4, Discussed

Held Monday, March 13, 2000

Overview

Today, we visit problems and questions from assignment 3.

Notes

• For homework 3, you were expected to tell each other about errors you'd found in each-other's code.
• Assignment 4 returned.
  • We'll go over some of the more difficult problems.
  • Many of you needed to acknowledge co-workers
  • Many of you needed to be more careful about assumptions
• Are there questions on assignment 5?
• I'll probably give out assignment 6 (on Chapter 3) on Wednesday and have it due on the Wednesday after break.

Contents

• Assignment Four

Summary

• Discussion of HW3

Assignment Four

Here's a series of questions that will help you think about some of my problems with your assignments:

• What is a CRC?
• What are legal values?
• Is ETX ETX a legal value for a sixteen-bit CRC?

The problems that most of you had trouble with were

• 6. (BISYNCH payload contains DLE ETX)
• 7a. (illegal BISYNCH sequence)
• 17. 32-bit error-detecting codes

I'll also spend a little bit of time talking about the proof for 2-D parity.