FOCAL8-185 LIFE

This document is a DECUS Program Library write-up (FOCAL8-185) for a FOCAL language program called "LIFE".

Summary:

The document describes a FOCAL (FOCAL8) implementation of John Horton Conway's Game of Life, developed by C. C. Wilton-Davies from RNPL, dated June 21, 1971.

The program simulates the game on a matrix of locations, where "cells" can be full (alive) or empty. Cells live, multiply, or die based on the following rules:

• A cell with two or three neighboring cells survives.
• A cell with zero or one neighbor dies of isolation.
• A cell with four or more neighbors dies of over-population.
• An empty location with exactly three neighboring cells becomes a new cell (birth).

Program Usage:

1. After a GO command, the operator specifies the desired matrix size.
2. The maximum matrix size is 4x4 for a 4K machine and 11x11 for an 8K FOCAL machine.
3. Users then input the X and Y coordinates of the initial "occupied cells" (live cells). Entering zero as a coordinate stops input and displays the starting matrix.
4. The program then prompts the user whether to plot the "next generation" of cells, allowing the simulation to advance.

The document includes a sample printout demonstrating user interaction and matrix output, and lists relevant references, primarily from "Scientific American" and "The Sunday Times," discussing the game.