Registers and RAM: Crash Course Computer Science #6

Registers and RAM: Crash Course Computer Science #6

Take the 2017 PBS Digital Studios Survey: http://surveymonkey.com/r/pbsds2017. Today we’re going to create memory! Using the basic logic gates we discussed in episode 3 we can build a circuit that stores a single bit of information, and then through some clever scaling (and of course many new levels of abstraction) we’ll show you how we can construct the modern random-access memory, or RAM, found in our computers today. RAM is the working memory of a computer. It holds the information that is being executed by the computer and as such is a crucial component for a computer to operate. Next week we’ll use this RAM, and the ALU we made last episode, to help us construct our CPU – the heart of a computer.

*CORRECTION*

In our 16×16 Latch Matrix graphic, we inadvertently left off the horizontal row access line above the top row of latches. As a result, the highlighted line for the row at address 12 should actually be one line higher.

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50 Comments

  1. jefry jefry on October 30, 2019 at 4:46 pm

    O_O WoW



  2. mohisin abbas on October 30, 2019 at 4:46 pm

    0.75 x



  3. Saskia van Houtert on October 30, 2019 at 4:47 pm

    She knows what she is talking about, thanks for explanation.



  4. L Schmidt on October 30, 2019 at 4:52 pm

    nitpick mode: I think what you describe at 7:50 is a demultiplexer ("demux"), not a multiplexer.



  5. pelegini50 on October 30, 2019 at 4:52 pm

    1:30 what would’ve happen if you were using the xor gate?



  6. christian37ism on October 30, 2019 at 4:53 pm

    I learned so much watching this video, much obliged!



  7. Jitox97 on October 30, 2019 at 4:57 pm

    She is the best teacher ever.



  8. محمد درارني on October 30, 2019 at 4:57 pm

    Explained fast



  9. Sean Hurt on October 30, 2019 at 4:58 pm

    How does the looping signal gain current?



  10. Samuel Drain on October 30, 2019 at 4:59 pm

    This video so good, it doesn’t require anymore dedicated wham!



  11. Evan karag on October 30, 2019 at 4:59 pm

    great job!!!



  12. Bishoy The Great on October 30, 2019 at 5:01 pm

    11:00 That sad green face looking at me



  13. Ærinmund Fågelson on October 30, 2019 at 5:03 pm

    I got a bit confused, how did we jump from a 64 bit memory register (8×8 latches) to a 256-bit memory piece?



  14. getreadytotube on October 30, 2019 at 5:05 pm

    In 12 minutes, she just did what most professors can’t do in 1 semester.



  15. Vincent Von Boff on October 30, 2019 at 5:09 pm

    I’m woke



  16. Jeremy Bailey on October 30, 2019 at 5:12 pm

    If you cut the power to the loop then how does it keep that charge going to remember the value?



  17. srinivasan cheenu on October 30, 2019 at 5:13 pm

    Well explained with interesting animation…need more information…keep going



  18. Himanshu Sharma on October 30, 2019 at 5:14 pm

    The best part abt this crash course is its going bottom up and explaining the abstraction concept really well. That gives a sort of completeness to knowledge:) Thanx for such a great course.



  19. swornim baral on October 30, 2019 at 5:14 pm

    Great Presentation! Thank you!



  20. Amanda Purello on October 30, 2019 at 5:16 pm

    Im so glad people figured this out before i was born



  21. Devin on October 30, 2019 at 5:18 pm

    Love these! Definitely becoming a patron! And posted to Facebook to get others to donate as well. I can’t wait to see what you guys do next!



  22. Victor Tecpa on October 30, 2019 at 5:19 pm

    Okay I had to watch this like 4 times to actually understand it.
    (I’m a slow learner)



  23. Avi Mehenwal on October 30, 2019 at 5:21 pm

    Best computers playlist ever



  24. Johnny Utah on October 30, 2019 at 5:21 pm

    when you put dots before the write enable on the 16×16 matrix, does that go into a grounding where the dots are? Just curious what if they had any significance.



  25. xganh zu on October 30, 2019 at 5:22 pm

    Soo can someone explain the link between pointers and what a pointer to a pointer is. I understand a pointer stores the memory address. The X and Y in our memory chip. But what does it mean to have a pointer to a pointer.?



  26. Nidhin Benny on October 30, 2019 at 5:23 pm

    I wish these guys were around when I was 12…



  27. Taripar on October 30, 2019 at 5:25 pm

    I’m a bit confused how the Write Enable, Read Enable, and Data In/Out are individual wires for all latches in the memory. In the illustrations they connect to the ether. Someone please explain how those three inputs are all still one wire when they have 256 different destinations.



  28. Raj Bhakte on October 30, 2019 at 5:26 pm

    The explanation is really good the only thing is that she’s a bit fast with her words…..if you’re a beginner you end up rewinding the video over and over to understand what was said. But nice explanation none the less. Hope she goes slower moving forward for the us beginners 🙂



  29. HAILSTONE AERIAL FILMS on October 30, 2019 at 5:26 pm

    Very well explained. However, unfortunately for me, I still have absolutely no idea what you are talking about. Onto the next episode, yay



  30. Cheisa on October 30, 2019 at 5:26 pm

    I’m still new to this things in fact I only knew them today Because I took a Course of Computer Science I’m still in my first year, first semester. I don’t understand this things but I keep Watching them hoping they can help me in the near future. Any Tips For me to be able to Learn more About Computer and to Graduate College. My Dream Is to Become a Game Developer Someday! I hope you guys can Give me some tips. 🙂



  31. Bruce Lee on October 30, 2019 at 5:28 pm

    5:46, what is this 256bit register?? Why 256?



  32. Md Nadim Sahbaz on October 30, 2019 at 5:28 pm

    The most important video if someone wants to know how memory works in a fun way and also this clears the concept at bit level.



  33. Ballista on October 30, 2019 at 5:28 pm

    Are Registers made out of latches or flip flops?



  34. shubham modanwal on October 30, 2019 at 5:28 pm

    it took me 30 min to understand properly..



  35. Sami Rahim on October 30, 2019 at 5:28 pm

    You are great teacher and good voice thank you very much



  36. Mains 00 on October 30, 2019 at 5:28 pm

    HELP PLEASE. I don’t understand how can you address 16 columns with only 4 bits. First, because when there is no electricity is when the wires are 0000, therefore i don’t understand how can be selected a wire without electricity. And second, because there must be logical AND gates connected to certain wires so the electricity go there, for example: if 1010 is 10 in decimal, the first and third wire should be connected by an AND gate to the column 10; thats the only solution i came with but, because it’s not explained, i don’t quite get it. If someone could explain it to me I would be grateful. Thank you very much. Great video, for the rest I understood everything.



  37. BsHr Алвани on October 30, 2019 at 5:29 pm

    i wonder why you make it so complicated:
    the first thing the combination of a simple bit memory you made is so complex and hard to understand
    and you had to explain the bus and how if you enable on memory bit how the stored bit will get take control of the bus and every memory bit shared with that bus would take the same values of that bit if it’s "SET" was on
    the buss is important and why they took byte as their main unit because it represent one unit of info which is represented in letters in ASCII and that can take various places
    the memory combination can be simplified with NAND gate



  38. Sontapää11 Jokulainen on October 30, 2019 at 5:31 pm

    2:43 I built this exact circuit and i remembered to add a resistor before each base of a transistor and when i power on the circuit, the led starts of not on and then when i put the reset pin (bottom pin in picture) high the led stays off (as expected) but when i put the set pin (upper pin in picture) high the led at the output comes on (as expected) but when i put the set pin back low the led DOESN’T stay on. Any help?



  39. Guillaume Paquet on October 30, 2019 at 5:31 pm

    Very precious episodes, thank you very much!



  40. Kiki Rizki Arpiandi on October 30, 2019 at 5:32 pm

    What is the circle symbol at 06:38



  41. Wizzard on October 30, 2019 at 5:32 pm

    Isn’t it easier to just use D-latch ?



  42. JakkuWolf Insomnia on October 30, 2019 at 5:35 pm

    I love these videos you explain and display everything so extremely clearly, the gap between logic gates and programming has until now always been blurred from poor explanations or not enough visible learning materials. I really appreciate your videos because they have allowed me to understand what is exactly happening under the hood and understanding each individual component as well as how this translates into programmability. Thank you so much my interest in computer science was dwindling until I watched your videos, you’ve re-ignited my passions thousands of folds greater than before! I can’t thank you enough I’m so excited to watch your next videos!! 😊😆



  43. Patrycja Chrzaszcz on October 30, 2019 at 5:35 pm

    I only understand about 30% of this



  44. qu4ku on October 30, 2019 at 5:37 pm

    man. this course is so good.



  45. Raja Saad on October 30, 2019 at 5:37 pm

    You deserve a Nobel Prize. You are making our lives a lot easier. Love from Pakistan.



  46. محمد درارني on October 30, 2019 at 5:38 pm

    Now we know how memory works ,what we can do with knowledge?!



  47. Dynamosaurus on October 30, 2019 at 5:41 pm

    MIND. BLOWN, BABY.



  48. Farhan Ishrak Ahmed on October 30, 2019 at 5:41 pm

    I am a doctor… Why am I learning this?



  49. KayBe on October 30, 2019 at 5:43 pm

    FYI – Sram means ‘Im taking a dump" in Polish



  50. shubham Kapoor on October 30, 2019 at 5:43 pm

    your efforts to explain these concepts are priceless for me