Rom size?

Discussion in 'General Electronics Chat' started by morgan, Jul 10, 2010.

  1. morgan

    Thread Starter New Member

    Jul 10, 2010
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    I want to realize a combinational logic function that can perform the function of a 74*381 by using a particular size of a ROM. Could anyone tell me what kind of ROM should I use?
     
  2. tom66

    Senior Member

    May 9, 2009
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    ROM = Read only memory (?)

    How would some ROM realise a logic function?
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    A number in brings a number out. A truth table in other words. Old tech, but it works well.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    A 74381 is a ALU (arithmetic logic unit). It has 12 inputs and 6 outputs. That means it has 2^12 bits X 6, or 4,096 X 6 cells. Seems doable, but a real pain to program.
     
  5. morgan

    Thread Starter New Member

    Jul 10, 2010
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    Does each ROM need one output or six outputs?
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I'm thinking there are 4K X 8 ROMs out there, but more than that I can not help with. The X 8 is the data width of a 8 bit word. You are going to also need an EPROM programmer.
     
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Bill is right. An 2732 eprom would work.
    http://www.futurlec.com/Memory/2732A-200.shtml

    They are not realy fast but they will work.
    On the shown page you can aslo download the datasheet.
    You will need a promprogrammer to put the data in the chip.

    Bertus
     
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