hey, im trying to make a BCD TO EX3 converter using 1 Decoder 4->10 and 4 NAND Gates.
i really lost and i dont really know from where i should start, it will be helpfull if you could give me an hint or tell me what i should start with.

thanks!

 

I'm lost too.
What's an EX3 converter?

 

I'm lost too.
What's an EX3 converter?

excess 3 , i cant edit my post.

 

hey, im trying to make a BCD TO EX3 converter using 1 Decoder 4->10 and 4 NAND Gates.
i really lost and i dont really know from where i should start, it will be helpfull if you could give me an hint or tell me what i should start with.

thanks!

The first thing is to be sure that you understand the problem.

Do you understand what BCD is?

Do you understand what EX3 is?

Can you make a table showing what the EX3 output should be for each legal BCD input?

Do you know what the output should be if the input is a nonvalid BCD encoding?

Do you know what a 4->10 decoder is and what it outputs for each input?

Are the four NAND gates all two-input NAND gates?

 

The first thing is to be sure that you understand the problem.

Do you understand what BCD is?

Do you understand what EX3 is?

Can you make a table showing what the EX3 output should be for each legal BCD input?

Do you know what the output should be if the input is a nonvalid BCD encoding?

Do you know what a 4->10 decoder is and what it outputs for each input?

Are the four NAND gates all two-input NAND gates?

Hey!
yes i know those things , but i dont really understand how to use all this information.

i added a solution for my question, but again, i dont really understand how to do it.

 

Your solution uses inverters, which were not listed as allowed components, and 5-input NAND gates (which is why I specifically asked if you were limited to 2-input NAND gates).

It's very difficult to provide guidance when you don't give the complete constraints of the problem and won't even show an attempt at a solution.

With unbounded input NAND gates and unlimited use of inverters, the solution is trivial. Look at the set of BCD inputs that should result in the MSB of the EX3 output being HI. Now look at the signals that go into the inverters connected to that NAND gate. Now consider what the equivalent gate is for a NAND gate in which all of the inputs are inverted (hint: think DeMorgan's).

 

Your solution uses inverters, which were not listed as allowed components, and 5-input NAND gates (which is why I specifically asked if you were limited to 2-input NAND gates).

It's very difficult to provide guidance when you don't give the complete constraints of the problem and won't even show an attempt at a solution.

With unbounded input NAND gates and unlimited use of inverters, the solution is trivial. Look at the set of BCD inputs that should result in the MSB of the EX3 output being HI. Now look at the signals that go into the inverters connected to that NAND gate. Now consider what the equivalent gate is for a NAND gate in which all of the inputs are inverted (hint: think DeMorgan's).

sorry about that...
thanks alot for your help, i finaly understand what is going on! [=

 

Glad to hear it. Understanding is what it is all about.

 

...and unlimited use of inverters..

But what if the decoder used active LOW outputs? Such devices exist!

 

But what if the decoder used active LOW outputs? Such devices exist!
View attachment 119503

Then you wouldn't need them. But when someone just mentions that they are using a decoder, the implicit polarity of the logic inputs and outputs is positive logic. Just like the implicit polarity of the inputs and outputs of a NAND gate are both positive logic. Negative logic chips also exist (don't know if they are still made and sold that way, but they used to be).