The Northern Lights: Demonstrations

1
The Northern Lights Demonstrations
2
Programmability Overview

• A major aspect of our project is
  programmability- it is an interactive display
  medium, the scope of what can be displayed is
  limited only by the creativity of the users.
• We have prepared demonstrations of two potential
  programs.

3
Conways Game of Life

• Conways game of life is a simple cellular
  automaton, which can be easily visualized in a
  system like the Lights. Each cell in a grid is
  either alive or dead (on or off, in our case). If
  a cell has two or less live neighbors, it is
  always dead, if it has three, it is unchanged,
  and if four or more neighbors are alive, it is
  becomes alive.
• When the grid is seeded with a few live cells,
  complex patterns emerge by following these rules.

4
Video Life

• (if video does not play, load the file life.avi)

5
Interactivity

• The game of Life is an example of a program that
  can be run either automatically or interactively
  people walking on the grid can cause cells to
  live or die, or the system itself can randomly
  seed live cells.

6
The Ripple-Carry Adder

• Another use of the Lights is visualization of
  data or processes. In this case, we have created
  a demonstration of a basic logic circuit a
  ripple carry adder.
• This program is a practical learning tool, and
  serves to bring the usually invisible processes
  that information technology is built upon to the
  human scale.

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Ripple-Carry Adder Technical Details

• Cells on the far right of the grid are
  user-controlled inputs, cells on the left are
  outputs. Numbers are represented in binary, with
  the least-significant bits at the bottom of the
  frame. The adder takes two 3-bit numbers (on the
  top and bottom), and determines their 4-bit sum.
  Red colors indicate wires carrying zeros, and
  blue colors ones. Yellow cells are XOR gates, and
  magenta cells are AND gates.
• In the video, the adder is first set to show
  000, then inputs are adjusted to show 022 (or
  0000100010), then 224 (0100100100), then
  268 (0101101000).

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Video Ripple Carry Adder
4 Input A 2 1
8 4 2 1

• (if video does not play, load the file adder.avi)

4 Input B 2 1