1) I hav seen some text's mention XOR gate as a universal gate...Is it true ?
2) Does an edge triggered circuit have race around problem......Isn't it applicable only to level triggered circuits..?

 

Can you show us the texts where you have seen this information?

As a suggestion, why don't you give us what you think are the answers to these questions and we can help you from there. Learning on here is a two way process.

Dave

 

1) No
2) Race conditions happen in asyncronous circuits. Edge triggered and level triggered circuits are both syncronous. Syncronous circuits have a related problem called metastability, which is related to setup and hold time violations.

 

I saw this as a question in the text "Digital Design Principles and Practices"
by John F. Wakerly.......
it was given in the text in the form of a question .........the question was......Is there any other gate other than XOR, NAND & NOR that can be configured as a universal gate....

 

1) I hav seen some text's mention XOR gate as a universal gate...Is it true ?

Looking at an XOR gate, you can make a NOT gate by tying one of the inputs to Vdd, but I can't see you can make an AND or OR gate.

As a curiosity, in the "Digital Design Principles and Practices" textbook, can you tell us how the author expresses the concept of Universal Gate?

Thanks.

2) Does an edge triggered circuit have race around problem......Isn't it applicable only to level triggered circuits..?

If the hold-time is large and the contamination delay is small, then data in an edge-triggered pipeline (for example back-to-back registers) can become corrupted. This is the race condition, also known as a hold-time failure, and is only overcome through logic-system redesign and not by alteration of the clock-rate.

Dave

 

the concept of universal gate is the same "a gate which can be used to realize the basic gate (AND,OR,NOT), as well as any other logic"........if it possible to realize a NAND or NOR using XOR then the job is done....

 

I have to start graveyard shift on Monday night, so I'm staying up as late as I can tonight. I just spent about 2.5 hours playing with XOR gates in Eagle Light, trying to get a NOR or NAND result. No dice.

I got several combinations which would follow one input or the inverse while ignoring the other input. I got many which were simply XOR or XNOR. I got a few which always output a zero or a one, regardless of i/p.

I won't say it can't be done just because I couldn't do it, but I will say that it won't be done my me. I'm going for a walk now.

 

From experience with older computers, I would sugest that the NOR gate is quite universal, as is the NAND. Like thingmaker, I can't see how to make much of anything out of an XOR gate, or combinations thereof.

As an exersize, try making a 2 input AND gate using the XOR function.

 

Gentlemen. There is no point in making the attempt, the XOR is not universal. I believe NAND (aka Sheffer Stroke), and NOR (aka Pierce Arrow) are the only universal logic functions over the boolean algebra of two elements.
http://en.wikipedia.org/wiki/Sheffer_stroke
http://en.wikipedia.org/wiki/Logical_nor
http://en.wikipedia.org/wiki/Functional_completeness