FOCAL8-149 Checkers

This document describes "CHECKERS," a computer program (DECUS No. FOCAL8-149) developed by Paul M. Klinkman of North Smithfield Jr. Sr. High School, Woonsocket, Rhode Island, dated April 1, 1971.

Written in FOCAL, the program allows a human player to compete against the computer in a game of checkers. The 8x8 board is stored as variables A(1)-A(64), efficiently using only 32 active spaces. Computer checkers are represented by 1 (or 2 for queens), and player checkers by -1 (or -2 for kings).

The computer's move logic involves:

• Identifying possible moves, including four for queens.
• Prioritizing and executing any available jumps.
• If no jumps, attempting a "thrust" move (advancing a checker with another behind it) to gain a strategic advantage.
• Randomly selecting a move if multiple legal options exist (thrusts preferred).

The program outputs the checkerboard using letters C, O, Q, K, and '#' for empty spaces. A significant limitation is that the program does not validate the player's moves, and illegal inputs can lead to errors or memory issues. The document notes that memory constraints limited further refinements to the computer's strategy or user interface.