Abstract: A pocket-size portable electronic device for playing chess problems comprises an electronic visual display, a display driver, an 8-digit keyboard and scanner, function keys and scanner, a random access memory, registers and counters, and a logic control unit which includes a switchable data bus controlled by a read only memory, a ROM pointer and a clock. The logic control unit decodes entered coded groups of data according to a special decoding algorithm, the decoded groups represent white and black moves for solving a chess problem. The groups are stored in a random access memory in use. The device responds to specific white moves input. If the input white move is the same as the stored corresponding white move, the device will display the next black move. The user then decides upon his next white move, the play is continued until the problem is solved by the entry of correct white moves.