Fast and Efficient Searching
In the 1970s, chess software made dramatic progress. The programs CHESS, KAISSA and Belle introduced several novel features, many of which are still used today.
Among these are:
Chess Hash Tables: a way to quickly check a catalog of positions already examined, which cuts down the number of positions that must be searched.
Iterative Deepening: a technique that gradually increases the depth of the search tree (the number of moves and counter-moves) that is examined, rather than searching to a fixed depth. This allows the most efficient use of the limited time each player is given to choose a move.
Bit Boards: a mapping of the chess board squares to the computer’s internal binary structure, which allows the computer to store and analyze board positions very efficiently
Opening Books: a listing of known good move sequences that can be used at the beginning of a chess game.
Endgame Databases: a catalog of previously analyzed board configurations near the end of a chess game that allows the program to play the remaining moves of the game flawlessly.