Latches and Flip-Flops 1 - The SR Latch

This is the first in a series of computer science videos about latches and flip-flops. These bi-stable combinations of logic gates form the basis of computer memory, counters, shift registers, and more. In particular, this video covers the set-reset latch, otherwise known as the SR latch. It begins by reviewing the basic building blocks of SR latches, namely NOR gates and NAND gates, then goes on to describe the workings of an ‘active high’ SR latch built using NOR gates, and the workings of an ‘active low’ SR latch built using NAND gates. Truth tables that describe the behaviour of SR latches are also covered, including the invalid combination of inputs that might result in a race condition. Applications of SR latches are mentioned, such as mechanical switch de-bouncing. The videos that follow this one build upon the principles covered here and include the gated SR latch, the gated D latch, edge triggered pulse latches and the master slave D type flip-flop.

[tensorbundle]

In my 12 years of engineering education, you are first professor who clearly and concisely explained the SR latch operation without causing any confusion. You are a genius. Thank you sooo much

[latedeveloper]

1:30 NOR gate and NAND gate explained
2:25 NOR gate and NAND gate can be used to make an S-R latch
2:35 Cross-coupling of 2 NOR gates in an S-R latch
3:17 Starting state of this S-R latch example
3:55 Resetting the latch
4:17 Pulse removed
4:25 Applying another pulse and implications
5:05 Implications of applying a pulse to S
5:27 Truth table
6:15 Truth table after applying a set pulse
6:25 Truth table after removing the set pulse
7:15 Race condition
8:00 Active High S-R Latch Explained
8:41 Truth table for Active High S-R Latch
9:20 Active Low S-R Latch (i.e. built from NAND gates)
9:44 Forbidden state of the S-R latch built from NAND gates
10:00 Summary
10:37 Switch bounce problem
11:37 Examples of applications of an S-R latch

[SnoozeDog]

This video better than any other explanation, short to the point

[stevenmcg]

I am currently taking a digital fundamentals class for my  computer degree and I have been struggling a lot with these chapters that are starting to cover latches and flip flops. I have a difficult time comprehending material simplify by reading out of the text book, and I've tried several videos on YouTube to help. None of them have worked; they have still been too confusing. Your channel has been a blessing so far. Very easy to understand on how slow you explain the information and the visuals are good. I'm going to continue watching them all and taking notes. Thank you!

[DanilKarlos]

Finally a perfect explanation with a great and easy to understand accent

[jdb]

Thank you!
Thank you for you hard work, as a scientist and an educator!
Thank you for putting the time into these videos!
Thank you being British, as sometimes I forget I'm not watching a great BBC documentary!
Thank you, Sensei!
Thank you!

[samsonmayeem]

I am offering my college degree i got confused today in my computer architecture lecture.With this video i am now a good "comprehender"! wishe that i get a lot of your tutorials to enhances most troubling concepts. you are a great teacher. Thank you.

[luckypi]

BY FAR the best SR Latch and FlipFlop explanation video series on Youtube! Please keep making videos. Excellent

[pablakes]

Your teaching style is incredible. Thank you for all the work of sharing these lessons for free!

[yusufkenanturak]

Finally excellent source for Logic Circuit, Thanks from Turkey.

[TopLobster]

I'm a distance-learning student going to Arizona State (electrical engineering) and I cannot thank you enough for these videos. It's difficult to get help from the professor as he teaches in the classroom, and the forum we use, Piazza, isn't always an active forum where people get a hold of you quickly. At least I can rely on somebody else's different point of view on this stuff. Thank you very much!

[DTHMTR]

One the clearest most concise videos out there on SR Latches. Much appreciated !

[Cosmos]

This is the first video I've come across that explains how these latches actually work and doesn't just input the values of the truth table onto a graphic. Thank you! It finally makes sense.

[shivangikansal]

great explanation and I appreciate that a practical example was also included in the video which made it really easy to understand :)

[aghasttoad]

My textbook tried to do this in two pages of text with no words. Thank you for making this bearable.

[FirstLast-vsgv]

Great video thanks! Best part is that you switch the inputs in realtime.

[albertlewis]

You are an amazing instructor. I've searching all over youtube and the videos that I've watched are not as clear and coherent as this video. My instructor has explained this concept but as it today after a couple of weeks taking his class, I was completely lost by his inefficient way to teach this "complicated" subject, but as it right now, I finally understand flip-flops and latches but I'm afraid that is too late and I may end up withdrawing from the class that I'm currently taking. One last thing, you are blessed with the gift of teaching.
Thank you so much and god bless you.

[mth]

This is one of the best explanations of the SR latch that I have ever seen.

[russiachan]

I didn't understand SR latches at all until I saw this. Thank you so much!

[HealthFactoryOfficial]

you are a life saver, now I understand the concept. Other youtube channesls were going through a lot of what you said like we already knew. This is easy to understand for any beginnger