Synchronous sequential circuit

Sequential and combinational logic elements are basic components of a digital system. During designing of a circuit, first step is to convert word description to algorithmic state machine chart. After this, state synthesis table is prepared. In flip-flop based circuits, these tables are used to generate design equations through Karnaugh Map. These design equations helps to develop the final circuit diagram. State machine design model is of two types- Moore model and Mealy model. If secondary outputs or memory values generates primary outputs, then the model is termed as Moore model. In Mealy model, primary inputs combine with memory elements to generate circuit output. A sequential logic circuit is a synchronous clock-triggered circuit. This can be designed in two ways. In the first model, output depends only on present state and not on input (Moore model). The other model (Mealy model) output is derived from present state as well as input. Since Mealy model requires less number of states, hardware requirement is minimum. After fixing any one of these models, next step is to fix the algorithmic state machine chart. After fixing this chart, state synthesis table has to be developed. The final stage includes usage of design equations and circuit diagram and implementation using read only memory.  

Game controllers

Computer games are becoming popular choice for time passing in the field of entertainment. Not even kids, grown up men/women too nowadays almost addicted to computer games. Any computer game requires some devices to input the data and to give commands. These devices are called as game controllers.  When a user gives input using game controllers, game program accepts it, processes it effectively and then produces output in the form of graphics and sound. The most commonly used game controllers are joystick and game pad. A joystick has a lever which the user can move to control the movement of a pointer. Joystick is the preferred choice in car racing and flying games. A game pad has a set of buttons which are known as action buttons and direction buttons. Gamepad can be controlled by using both the hands. Action buttons which are bigger in shape is used to control actions like increasing speed, stopping etc. For changing the direction, direction buttons are used. A game pad is also known as joypad or control pad.