Computer Science 237
Computer Organization

Lecture 20: SIMM Layout, Error Detection and Correction in Memory
Date: October 27, 2006

Announcements
- Second Sigma Xi talk this afternoon - Prof. Freund, 4:15, TCL 123, reception to follow
- Lab 8 next week - back in the digital logic lab
  - forming groups
  - come to TCL 312b during your regular lab times to get things started
  - your circuits must be complete and graded by Tuesday, November 7
  - no late submissions because of the exam coming right after this lab is done
SIMM Layout
- memory is not usually addressed one byte at a time
- retrieve/store several memory locations in parallel
- Uses "Option 2" layout
- Why is this helpful? Locality!
Error correction in memory
- A single parity bit: 1 bit error detection
- Single bit error correction
  - Add 4 bits in a way that makes any 1 bit error recognizable and correctable