MicroChess

published by Personal Software / VisiCorp in 1976-12-18, running on MOS Technology Keyboard Input Monitor-1

type: board game, strategy
genre: Chess
perspective: bird's-eye
player options: single player

languages: eng other

Description

The 1st chess program for home systems (AKA: "Microcomputers", at that time). MicroChess could defeat novice players. The board is displayed using text in overhead view and two-letter abbreviations are used to represent the pieces. This was of course on an external terminal, not the KIM-1'a LED readout. Commands, many of them single letter, having 0-2 arguments, are used to operate the game almost as if it were a computer operating system. Players could castle, en passant, and promote pawns. However, the game limited each player to having only 1 queen at a time (all other pieces were 'unlimited'). While special moves were recognized and performed by the computer, they were not automatically performed by the program on behalf of the player and required the player to manually edit the board using specific commands. From the manual: "GNM must be modified to spot the occurrence of situations in which the moves are available. The actual move calculations must be added to CMOVS, and a flag to indicate the nature of the move set to allow MOVE and UMOVE to properly interpret them. The flag could use the two spare bits in .SQUARE. Additional parameters wouid be required to indicate when castling, or en passant moves are legal during the game, because these moves depend upon previous play for their legality."
The manual contains basic documentation of the machine code and suggestions for customizing and improving the game including the possibility of having multiple queens per player. It also contains flow charts and a much more advanced examination of every detail of the machine code. Such help was common to game manuals during this era.

MicroChess for KIM-1 sold 50,000 copies! (did _every_ KIM-1 play MicroChess?). MicroChess was ported to other early systems where the game had better graphics, an easier interface, and improved gameplay options (ie: no need to understand machine code to perform a castle). Royalties from KIM-1 MicroChess funded the founding of VisiCorp that would go on to to create VisiCalc.

zerothis # 2021-03-06 22:17:32