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  1. Nov 27, 2004 #1
    Why is Static RAM faster than Dynamic RAM. Why is it so expensive to manufacture SRAM?
  2. jcsd
  3. Nov 27, 2004 #2
    I think your mistaken

    Basically DDR-SDRAM provides double the bandwidth of normal SDRAM. At 100 MHz memory clock it's able to supply a data bandwidth of 1600 MB/s, at 133 MHz it goes up to 2100 MB/s. That is why 'Team DDR' decided to call the specs of those two DDR-memory types 'PC1600' and 'PC2100' and the newer 'PC2700'. However, I have to disappoint you, if you should think that DDR-SDRAM is simply twice as fast as SDRAM at single data rate. The basic reason is rather simple. While DDR-SDRAM is indeed able to provide double the peak bandwidth of normal SDRAM, it has still the same (CL2 DDR-SDRAM) or even a slightly worse latency (CL 2.5 DDR-SDRAM) than its older sibling. The result is that in worst-case situations DDR-SDRAM can be as slow or even slightly slower than normal SDRAM. At the same time DDR-SDRAM can easily outperform single data rate SDRAM under ideal conditions. In average, systems with DDR-SDRAM are most certainly faster than systems with normal SDRAM.

    The main difference is in the amount of pins they have DDR DIMMs have like 184 pins and SDRAM DIMMs have like 168-pins.
  4. Nov 27, 2004 #3
    I’ll attempt an answer to your second question;
    Static RAM is flip-flop memory which uses more component parts per cell than Dynamic RAM. It will use up more real estate on your chip (by a factor as high as 4).
  5. Nov 27, 2004 #4


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    I believe you misread the question -- you just compared a lot of different kinds of DRAM, when the question concerns SRAM versus DRAM.

    BoulderHead gave the correct answer -- SRAM uses four or six transistor per cell, and responds immediately. SRAM is purely digital. DRAM uses a single transistor as a capacitor per cell, and requires a slow sense amplifier (a precision analog component) to recognize the contents of a cell. DRAM also has to be periodically refreshed, which slows it down a bit.

    - Warren
  6. Nov 28, 2004 #5
    Why is Level1 Cache faster than Lever2 Cache? Both use the Static RAM technology.
    Which level cache is measured as a parameter of CPUs?
  7. Nov 28, 2004 #6
    Level 1 cache has always been built directly into the processor die and runs at the same speed as the processor itself. Meanwhile, on early boards, the L2 cache was external and ran at the slower (asynchronous) speed of the motherboard. L2 was later built inside the processor chip and finally it was built inside the processor die itself (there is a difference between being those last two). If you do a search for cache memory on ebay you can still see the older, external, motherboard mounted L2 cache for sale and better understand what I’m talking about (it was often replaceable/upgradeable the way main memory is today). There were gains in performance in those evolutions of the L2 but the L1 cache is and always has been the ‘first line of defense’ when it comes to anticipating what data the processor is going to need next.
    I hope that is enough to give a general answer to your question. Going beyond this would be a discussion of the functions of cache memory.
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