[Part 1] Unit 3.2 - Flip Flops

In a previous unit, we discussed how we're dealing with time and sequential logic in computing systems. What we'll do in this unit is actually talk about the actual elements, the chips that will allow us to do, provide this kind of functionality. So, let us say, let us recall how we started the last unit where we started the way we deal with time, we add integer time units. At every time unit t, we want something that can depend with value to compute some kind of function and the output. Some kind of function and the value at the previous time unit, the time t minus 1. So what kind of element do we need in order to provide such a functionality? Well, the missing element, we need something as a very basic point, is we need something to actually remember one bit of information, move one bit of information from time t minus 1 to time t. This is what we have missing. We have lots of combinatorial log, logic so far that can do any kind of manipulations that we want within a single time unit. But actually moving information from time t minus 1 to time t is something that is still missing. Now, if we look about that kind of thing in the way we're, we're in this abstract way that we're thinking about these discrete time units, at that exact time when we switch between time unit t minus 1 to time unit t. This new element must remember the bit. At that point it has to remember what happened previously and carry it on to the next stage. Without that we cannot have this kind of functionality. Now, this means that at this transition point between two consecutive time units it must have state. It must remember whether it's now remembering 0 or it's now remembering 1. That means it has to be in two different physical states in, in its implementation. These two physical states, it must be able to move between them according to the logic of the previous time unit. Which means, which means it needs to be able to flip between these two kind of different, two, two different physical states. An element that can do that thing, that can flip change situation between two different kind of such states are called Flip-Flops. They flip to 0 and then can flop back to 1, and the point is that this flipping and flopping is something they remember. It's not just a function of the current input, but its something internal to them they remember between time units. So let us view now the basic flip flops that we will you, be using in this course which is called the Clocked Data Flip Flop. This flip flop has a single input and a single output and it basically remembers the input from last time unit and outputs it in the next time unit. So, if we again look at the diagram of our time units and assume that our input looks like this.