Challenging decoder question

[tonald]

I have no idea about how to use the two "enable inputs". (the second part of the question)
Thx

 

[Hayato]

You gonna design a decoder that is only going to work when E0 and E1 are active.

 

[tonald]

I ask the second part....

 

[Hayato]

A 3 to 8 decoder is a 3 to 2^3.
You enter with 3 bits and it gives you 8 outputs.

He wants a 13 to 2^13 decoder.

You enter with 13 bits and it gives you 8192 outputs.

You can reach that with some 3 to 8 decoders.

 

[Hayato]

For example, 2x 3-8 decoders allows you to build a 4 - 16 decoder. 4x 3-8 decoders, allows you yo build a 5 - 32 decoder. 8x 3-8 decoders, allows you to build a 6-64 decoder, and so on.

2 decods. = 4 bits input.
4 decods. = 5 bits input.
8 decods. = 6 bits input.
16 decods. = 7 bits input.

You have a sequence there. For 13 bits input you need 1024 decoders.