Logic Gates and RAM

The Revision Guide

Logic Gates - AND, OR and NOT Gates

With an 'AND' gate you need to have both switches on for the output to be turned on. For an 'OR' gate, one or the other has to be turn on for the output to be turned on. And for a 'NOT' gate there's only one input and one output and if the input is on, the output is off and if the input is off, the input is on. Logic gates process signals which represent true or false. Normally the positive supply voltage +Vs represents true and 0V represents false. Other terms which are used for the true and false states are shown in the table on the right. It is best to be familiar with them all. Logic gates are like binary, 1 is positive or 'on' and 0 is negative or 'off'