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Decoding Circuits Made by Adham Barghouti 20070316

Decoding Circuits Made by Adham Barghouti 20070316. What is a Decoding Circuit??????. It’s a circuit designed to choose a memory chip from a dozen of memory chips. For Example if we had the following Memory chips how will the system know which memory you want to Read/Write on. M1. M3. M2.

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Decoding Circuits Made by Adham Barghouti 20070316

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  1. Decoding CircuitsMade by AdhamBarghouti20070316

  2. What is a Decoding Circuit?????? It’s a circuit designed to choose a memory chip from a dozen of memory chips. For Example if we had the following Memory chips how will the system know which memory you want to Read/Write on. M1 M3 M2 OR OR

  3. Another way of understanding what the Decoding circuits that it’s the circuit connecting the Microprocessor with the memory via the Address bus thus giving each memory chip a unique address. Memory chip 8088 CS Address Bus Decoding Circuit CS or Chip Select is a one bit input that enables the memory on ‘0’ or disables it on ‘1’.

  4. The Decoding circuit uses the Addresses in a way in which to select a certain memory chip by having the output of the decoding circuit equal to ‘0’. Memory chip For Example CS The only for this OR gate to have an output of ‘0’ is for all inputs to be ‘0’. Thus it can be said that the address that this small decoding circuit is 000.

  5. A decoding circuit can be any logic components. It can be a simple OR or NAND gate, Decoder or any other selecting method. First the output of the NAND gate has to be 0 in order to select the desired memory. And therefore A0 , A3 , A5 should be 0. And the rest should equal to 1. So the address for this circuit is 11010110 which is D6h. The most common decoding circuits are NAND Gates and Decoders Memory chip What is the Address that the following Decoding circuit is addressing????? CS A0 A1 A2 A3 A4 A5 A6 A7

  6. Using the Decoder is Easier As you see using only A0 and A1 only as inputs for the decoder and the other address lines connected to the enable of the decoder we are able to Address 4 different memories Memory 1 D4h Memory 2 D5h Memory 3 D6h Memory 4 D7h Memory chip 1 Memory chip 2 Memory chip 3 Memory chip 4 Try finding the Addresses of each memory!! CS CS CS CS A2 A3 A4 A5 A6 A7 2x4 Decoder A0 A1

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