# Homework Help: Can someone show me what a 4 to 16 line decoder looks like?

1. Nov 5, 2005

### mr_coffee

Hello everyone, I was wondering if someone could send me a website or a picture that shows what a 4 to 16 line decoder looks like, thanks.

2. Nov 5, 2005

### EvLer

Here's a 2-to-4 http://www.play-hookey.com/digital/decoder_demux_four.html" [Broken], but what you'd have for 4 to 16 is basically add two more select lines and more outputs. Do you understand generally how they work? I just had exam over it.

Last edited by a moderator: May 2, 2017
3. Nov 5, 2005

### mr_coffee

Thanks, yes i understand how they work but i'm confused on how u extend the theory to a 4 to 16 line, they want us to use two 3 to 8 line decoders and 16 2 input AND gates, this is what i came up with...
http://img143.imageshack.us/img143/5981/lastscan8mq.jpg [Broken] look right? If it doesn't load the first time, hit the refresh button. THe site seems to be laggy

Last edited by a moderator: May 2, 2017
4. Nov 5, 2005

### EvLer

here's how we did it...

#### Attached Files:

• ###### decoder.pdf
File size:
40.3 KB
Views:
556
Last edited: Nov 5, 2005
5. Nov 5, 2005

### mr_coffee

ahh i c, thanks alot EvLer, makes sense to me!

6. Nov 6, 2005

### EvLer

actually AND gates in addition to 2 3-to-8 don't make sense to me... if anything, i would expect ORs.

7. Nov 6, 2005

### mr_coffee

Well in a decoder ur not finding the min terms...if u wanted the min terms then i can see why you would want ORs insteed of AND gates, but check this out, page 3 or 4: http://eshop.engineering.uiowa.edu/NI/pdfs/00/51/DS005122.pdf [Broken]

Last edited by a moderator: May 2, 2017
8. Nov 6, 2005

### EvLer

But that is not in addition to the decoder logic, i.e. the AND(NAND) are used in the logic of the decoder, that i know, but from the description it sounded like they wanted to use 16 gates in addition to a decoder.
perhaps i am missing something...

9. Nov 7, 2005

### mr_coffee

hah i have no idea either, god i wish there was a site that explained digital design, like this is the only course i can't find on the internet that has like tutorials and explanations, have you found any?

10. Nov 7, 2005

### EvLer

hmmm.... no not really, that play-hookey site that i cited before has some stuff, but it's not that much in depth. So, i just come across random sites , read my book (Wakerly):yuck: and bother my TA's :tongue2: during open lab hours.
edit: but we seem to have similar curriculum as you, guys... where do you go?

Last edited: Nov 7, 2005
11. Nov 7, 2005

### mr_coffee

We have no TA's hah, so i'm **** out of luck. and my book blows, its Kime, which sucks bad, he makes everything so complicated. I got to Penn State for Computer Engineering, u?

12. Nov 7, 2005

### EvLer

woooow....that does suck...
as far as the book, they have been using Wakerly (3rd ed.) Digital design: Principles and Practices, it's ok... i hardly ever read it though... but we have good lecture notes.... and TA's... well we have several... each leads at least one lab and office hours, and the Prof teaching/overseeing it is great. I'm a CompE at Purdue.

13. Nov 7, 2005

### mr_coffee

Cool, once i go to main campus next year (right now i'm at a branch, a very small branch) the TA's will be very abundant but for the time being i have to deal with the lack of assistance, oh well.

14. Nov 9, 2005

### Kenneth Mann

Actually, I have thought about putting a tutorial on K-Mapping on this forum, but I'm not sure that anyone would be interested. They are a lot more powerful than most people think. Also there is a lot of simple logic behind them.

KM

15. Nov 9, 2005

### EvLer

K-maps aren't bad when you get enough practice with them.
What would be esp. helpful is to show not only "how" but "why" it works. For instance, in my book Gray code is described in a chapter (which we did not cover) totally away from where the K-maps are. So, when it came to numbering of cells, i could not figure out the system .... until i happened to flip through the book out of boredom...and saw the Gray code and all that explanation.
But yeah... a thorough description would be a good idea. And also "where"/"when" they are useful besides when they explicitly say on the test.

16. Nov 10, 2005

### Kenneth Mann

Understood! I intend to try if I can, but first, I have to learn a little about how tutorials on this forum are handled, and on that I need some introduction. As example, I see tutorial sections on physics and math, but none on engineering and other subjects. Where would they be handled, and how? Any guidance here would be helpful. (BTW What ever happened to 'spell-check' on this forum?)

KM

17. Nov 19, 2005

### Kenneth Mann

If anyone is interested, I have started a K-Map tutorial thread.

KM