# Is it possible to construct a 6-to-64 line decoder using a 3-to-8 line decoders

Discussion in 'Homework Help' started by electrogirl, Oct 2, 2010.

1. ### electrogirl Thread Starter Member

May 2, 2010
47
0
Is it possible to construct a 6-to-64 line decoder using a 3-to-8 line decoders? if it is then how?

I know how to construct a 4-to-16 line decoder using a 3-to-8 line decoders by using 2 decoders and using one input as the enable input. But this one is different because it has lots of inputs and I don't know what to do with those other inputs.

Supposedly this is the given problem: Implement F(A, B, C, D, E, F) = ∑m(1,2,5,7,10,11,13,15,22,23,24,25,30,31,32,33,54,55,56,57,61,62,63) using a) 3x8 decoder

Just give me an idea on how this is done... i'll be the one who will do the implementation thanks ^^,

2. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
The way I see it, you will need 9 3-to-8 decoders. 8 of them will work in parallel and will service the 3 LSB's and one in front of them all will take the 3 MSB's and output the correct enable signal for the appropriate decoder.

electrogirl likes this.
3. ### electrogirl Thread Starter Member

May 2, 2010
47
0
thanks you are very helpful

4. ### idmond Member

Oct 5, 2010
18
1
Georacer is right. you can take outputs of one 3x8 decoder [Enable Decoder] as Enable Inputs for each one of the other eight decoders in such a way that only one decoder will produce its 8 combinations while the others are disabled by the Enable Decoder.

as for the 3 LSB's inputs, you can take them from any one of the 8 parallel decoders, but then you have to connect all the inputs of the other 7 parallel decoders to the one you first choose for the LSB's inputs.

here is a schematic for the 6-to-64 decoder in the attachments.

• ###### fig6x64decoder.png
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electrogirl likes this.
5. ### Georacer Moderator

Nov 25, 2009
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1,266
Thankfully, there are some people that are not afraid to bust a second sweat and design a diagram for the student.
Or do they actually hurt the student by giving him ready work?

I know I don't because of the first reason, anyway...

6. ### iam New Member

Dec 19, 2010
1
0
so helpful...
thnx a lot !!!!

7. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
We usually insist that the student post up some work to see that the exercise is not just a straight gimmie. Very little learning takes place when someone simply obtains a complete answer

See the post from the latest OP. He gets the grade, and I suspect that idmond gets no credit for actually having done the work.

I would not particularly care to erase all such problem-solving schematics, but rather encourage everyone to recall the educational aspect and not simply hand over complete solutions on demand.