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RAM memory diagram using decoders

  1. Feb 8, 2017 #1
    1. The problem statement, all variables and given/known data
    Draw a block diagram of [itex]32kx8 bit[/itex] RAM memory using decoders [itex]DEC 3/8[/itex] and memory components [itex]8kx8 bit[/itex].

    2. The attempt at a solution
    First we find the number of memory components:
    [tex]N=\frac{32kx8}{8kx8}=\frac{2^{18}}{2^{16}}=4[/tex].

    The number of decoders is
    [tex]32/8+1=5[/tex]

    There are 4 blocks of memory so the decoder needs to decode 2 address lines to 4 select lines (these are connections between memory elements and four decoders (see attachment)).

    Is this diagram correct?
     

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  3. Feb 12, 2017 #2

    Baluncore

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    Science Advisor

    You have made it too complex. Why do you think the number of decoders is 32/8 + 1 = 5 ?

    DEC3/8 means 3 binary input lines with 8 outputs. Note that 2^3 = 8. But only one of those 8 outputs will be active at the time.
    You will have 4 memory blocks. Which positions will they map to? 0, 1, 2 and 3 ? or somewhere else, maybe 4, 5, 6 or 7 ?
     
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