Basic program listing. The subroutine TKP just scans the keyboard waiting for an appropriate key to be depressed. The alpha- numeric entry is then translated to a board address. Move produces a list of all legal moves available to the piece under consideration. Pawn produces a list of all possible legal moves including initial double moves.
Check locates current mover's Kings and stores the position in the attack register.
Square Attack determines whether the opposition can attack the square in the attack register. It is also used to shift the best move so far up into the move list. MPScan scans the board for computer pieces and, using move and score, determines all legal moves and saves the best. INC determines whether a square is being attacked. Driver Main control logic, uses all the other subroutines to provide program control.