Version 1.1 Screenshots
On my original Tic-Tac-Toe page, I said I would provide some high quality screen shots of version 1.1, and here they are. The big images are around 2MB each.
Level Entry Gate
Since Tic-Tac-Toe is a two player game, you can’t start playing until two players are in. The entry gate system requires that one player stands in each ‘cell’, at which point the inner gates close, the outer gates open and allow you to drop down to your side of the board.
This is an overview of the board. Each cell has two emitters, three switches (Piece present – Yellow, O present – Red and X present – Green) along with the ‘reset’ stomper and the cell lamp for highlighting. These, along with the entry gates are connected to the control logic by an estimated 128 wires.
Once in the game, each player has three controls. A lever they use to select the target cell (highlighted with the blue light), a push button to place (in the center of the screen) and an exit/reset push button near the exit gates on either side of the platform.
Obviously an important part of Tic-Tac-Toe is being able to select where you want to move. Originally there was only a single selector that the players shared… but that means you both need to have access to it and that wouldn’t do when you win… don’t want to share your prize bubbles with the loser. So, this section of the control logic provides the two cell selectors and the logic that combines their outputs based on whose move it is.
Once you’ve selected where you want to go, you need to put your piece in the board. This section of the control logic takes the output from the cell selector and drives part of the lamp control circuit that handles highlighting cells. The big rack on the left handles only allowing valid moves. The next one drives the emitters and the final section uses a toggle (derived from Netty’s Advanced Logic tutorials – if I recall correctly) to decide who’s turn it is.
There are only eight ways to win a game of Tic-Tac-Toe (top row, middle row, bottom row, left column, middle column, right column and the two diagonals). These two honking racks of logic contribute an awful lot to the wiring (requiring 24 connections to the board each). They are basically AND gates that look for winning combinations, we need one for each player… or do we?