What logic (gate) do you need to use to decode 9?
View attachment 100084

A and D must on.. right? cuz' 8+1 = 9?

 

- ahh the 7 segment!! sorry..

- i forgot to connect it in the ground.. >o<

The decoder is connected okay. I mistook your upside down power symbol as ground. You should avoid doing that because of that...

- shout i connect R(9) in input?

You don't need the "reset to 9" functionality.

 

PROGRESS!!!

 

A and D must on.. right? cuz' 8+1 = 9?

That's correct. Now how can you decode 9 and use that to reset the counter to zero?

 

Q0 and Q3 must on the ground? O.O?

 

lol its not xD

 

Q0 and Q3 must on the ground? O.O?

You just said 9 is when Q0 and Q3 are 1...

Look at the table in post #38.

 

Look at the logic diagram of the 7490. What does it mean for a Q outputs vs a Q with a bar over it?

 

lol its not xD

What does this mean??

 

Look at thView attachment 100083e guts of the 7490, then see if your answers make sense...

......... cant understand it T^T >o< H, L, X of supply?

 

QA and CLKB must connect for the loop..?

No. That is totally wrong. A properly working synchronous circuit will have only one clock source and not two. [This is not a synchronous counter, so the previous comment is irrelevant.]

In order to do this you absolutely have to read the datasheet. You may get through school by having other people do your work for you, but you will fail in your first job to your everlasting shame and embarrassment. So lift your chin up and just read the datasheet. It will take you less time to read it than it will arguing with us.

 

H, L, X were explained in an earlier post. The chart shows state of the signal on various pins for various conditions.

 

Please give some hint.. Do i need to focus only in 74ls90?? nothing more? the changes are only in 74ls90?

The 74LS90 is a good start. But any 4-bit counter would fit your needs.

 

If you haven't yet learned what H, L, and X represent, then you need to stop trying to design a logic circuit like this and go back and learn the basic fundamentals.

 

The 74LS90 is a good start. But any 4-bit counter would fit your needs.

Most of the Posters with questions on 74LS90/92 and/or 74LS47 are doing school work and that's what they're told to use...

 

No. That is totally wrong. A properly working circuit will have only one clock source and not two. In order to do this you absolutely have to read the datasheet. You may get through schoolw by having other people do your work for you, but you will fail in your first job to your everlasting shame and embarrassment. So lift your chin up and just read the datasheet. It will take you less time to read it than it will arguing with us.

no i dont. I am the one whos doing my works. Its not bad to ask what you dont know, right? I just cant express what i want to say thats why my words are lacking.. I dont have any idea about this because my major is about Computer Hardware/software.. Our professor are not food spooning thats why I cant understand what I must understand.

 

Computer hardware consists of many circuits that are much more complicated than what your assignment is.

 

H, L, X were explained in an earlier post. The chart shows state of the signal on various pins for various conditions.

so I just need to figure out on how should i stop the connections to 9, right? Through the logic gates?

 

That would be one major step in the overall problem.

 

Our professor are not food spooning thats why I cant understand what I must understand.

Keep focused on your problem. You're almost there, but you don't have time to be distracted.