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Everything about RAM

  1. Apr 15, 2016 #1
    Allo,

    Introduction:
    I want to know the insides and outs of ram, mainly the hardware side of things. I know the concepts of RAM and other computer parts like CPU's, Graphics Cards, etc, and how they relate to each other in computer architecture. I know basically that RAM is temporal memory storage used for applications and software. RAM gets data from the hard drive when booting and sends this back and forth to the CPU. I also understand basics of electronics and common components like capacitors, resistors, transistors,etc. I just mainly want to know everything about the hardware side of RAM. Hopefully at the end of studying RAM I might be able to make a basic form of RAM.

    Inquiries:
    I have read a website about RAM, (note the multiple pages at the end).
    http://computer.howstuffworks.com/ram1.htm
    It goes through the principles of the hardware and structure of RAM. It goes through some of the parts like the 'memory controller' and functions like 'parities'. I have also learned what DRAM and SRAM are.
    Also I have found several other sources including Wikipedia about RAM and memory cells.
    https://en.wikipedia.org/wiki/Random-access_memory
    https://en.wikipedia.org/wiki/Memory_cell_(binary)
    Also I have found several diagrams, (refer to fig.1, fig.2, fig,3 and fig,4).
    However I have several questions.
    1. How does the sense amplifier when reading a bit work in a DRAM?
    2. How does the RAM refresh the capacitor in a DRAM?
    3. What is the configuration of a chain of SRAM cells?
    4. How does the controller address cells?
    5. What type is used more commonly? I have heard that SRAM is used more for CPUs caches, ( which I know what they are), and DRAM is used for RAM, is this true?
    6. Are there any other types of RAM I should be aware of?
    Structures:
    I would also like further diagrams and pictures of RAMs and memory cells for example one of SRAM. Also I would like to learn a bit more about the memory controller and other parts instead of memory cells. Also I would like to know about functions like sense amplifying, refreshing and error checkers.
    Also extensive explanation of those diagrams will help.


    Would not expect a complete knowledge of RAM in a few weeks.

    Thanks in advance.
     

    Attached Files:

  2. jcsd
  3. Apr 15, 2016 #2

    Baluncore

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    1. The sense amp is a mosfet gate that senses the voltage on the capacitor.
    2. It reads and then re-writes the capacitor often enough to prevent loss of information.
     
  4. Apr 15, 2016 #3
  5. Apr 15, 2016 #4
    SRAM is faster to access since for one reason it doesn't need a refresh cycle, but consumes a bit more power to operate. ( ie accessing the memory )
     
  6. Apr 15, 2016 #5

    phinds

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    When you say "temporal" I assume you mean temporary, so let me broaden your horizons a bit. "RAM" does NOT stand for "volatile" (temporary) memory, it just stands for "random access" memory and the two concepts are not even remotely the same. Early computers had non-volatile RAM, using little iron donuts with 3 wires running through each. The donuts were magnetized to indicate 0 and 1 and they maintained their state after the power was turned off.

    This is not particularly useful information in today's electronics, except to help you understand the fundamental meaning of RAM.
     
  7. Apr 15, 2016 #6
    More useless Trivia:

    RAM was a big improvement on early memory which was read sequentially. Basically all the memory was on a loop, one bit at a time. To read or write you needed to wait for your bit to come up in the sequence.

    So what RAM meant was that any random location could be read as fast as any other.
     
  8. Apr 16, 2016 #7
    Can perhaps give a diagram of the sense amp MOSFET in raltion to the memory cell grid?
    Is the refreshing cycle pulsing?

    I already know this stuff. You do not have to re-educate me.
     
  9. Apr 16, 2016 #8

    phinds

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    And we would have known that from your post, how? Being dismissive of people who are trying to give you information is not a good idea. Nothing wrong with saying you already know it, but your tone is too brusk.
     
    Last edited: Apr 17, 2016
  10. Apr 16, 2016 #9

    Baluncore

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    There are many answers to such a general question. At the risk of giving you information you already know, I will refer you to a search engine called google that may be of some help.

    Many of us have spend several decades working with electronic memory systems. None of us knows or will ever know “everything” about RAM. Your desire to know “everything about RAM” immediately denies the vast complexity and the long history of the field. You are also asking us to spoon-feed you in a very inefficient way, but then you spit it out if you have tasted it earlier. Maybe when you focus your question on a specific device, an answer might be formulated that could be of interest to you.
     
  11. Apr 17, 2016 #10
    I am sincerely sorry for my tone. It was just that I felt a bit 'patronized' but you shall have my apology.
    I am not expecting to get a PhD in Computer Engineering but just basics of hardware technology.

    However I am extremely sorry and will stop with this thread or maybe lock it if it is not of this forum.
     
  12. Apr 17, 2016 #11
    Sometimes it's hard to know a poster's knowledge level. I did not mean to be patronizing, but simply add somewhat useless historical knowledge on the origin of the word. Perhaps I should have saved that for the history forum.
     
  13. Apr 17, 2016 #12

    anorlunda

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    It sounds like you may be interested in the design of digital integrated circuits at the device level. You should follow that line of study. RAM is just one of the many applications of that that you can study later.
     
  14. Apr 20, 2016 #13
    Not all of the "insides and out" are even publicly available. If someone on PF happened to be a staff scientist at Micron Tech, there is no way that they would be willing to share *everything* they knew about RAM.
     
  15. Apr 20, 2016 #14

    phinds

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    Well, they MIGHT be willing. If they didn't mind getting fired. And probably sued for more than they are worth. :smile:
     
  16. Apr 20, 2016 #15
    Say, "more than they have." I'm sure all PF regulars are worth far more than they get paid. :oldwink:
     
  17. Apr 25, 2016 #16

    analogdesign

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    While what you say is true, the main reason SRAM is faster (and uses more power and takes up more area) than DRAM is each SRAM cell contains small amplifiers in it to buffer the logic value from the column capacitance. The DRAM is a passive device and depends on amplifiers at the bottom of the columns (sense amps).
     
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