Digital Electronics - Shift Registers - Discussion


The bit sequence 0010 is serially entered (right-most bit first) into a 4-bit parallel out shift register that is initially clear. What are the Q outputs after two clock pulses?

[A]. 0000
[B]. 0010
[C]. 1000
[D]. 1111

Answer: Option C


No answer description available for this question.

Mukesh said: (Sep 3, 2011)  
Reason is most simple for this. Serially two bits are in that is 0 followed by 1. Dey will demain at leftmost two bits of parral outcome and rest two bits will b zero.

I. E 1000.

Priya said: (Aug 31, 2013)  
After reset what is the result. I don't understand it.

Megha said: (Oct 15, 2013)  
First of all right most bit of 0010 that is 0 is sent. Due to parallel data out after 1 clock pulse output will be 0000. Now for second clock pulse second bit from right '1' is sent so similarly parallel data output '1000' will be the Result.

Venkatesh said: (Oct 30, 2013)  
Question 1 : Answer since q3=1 its complement will be q3=0 it is fed to q0.after fifth clock pulse q0=0.and q0=0(previous) was pushed to q1 so q1=0 and q1=1 is pushed to q2 the q2=1 and q2=1 is pushed to q3=1.

q0=0 q1=0 q2=1 q3=1.

Keerthi said: (Sep 28, 2014)  
1st time all the FF clear i.e) 0 states and then we give the i/p 0010.

As 1st clk the o/p is 0000 and then the 2nd clk the o/p is 1000.

3rd clk the o/p is 0100...4th clk the o/p is 0010.

Shubham said: (Nov 4, 2016)  
It's simple, assume initial outputs are 0000 (Q0, Q1, Q2, Q3) first of all it is serial in, so for the 1st clock rightmost bit of input i.e 0 is inserted.

SO OUTPUT BECOMES 0000 then in 2nd clock 1 is inserted and the output becomes 1000.
So answer is C in short initially -> 0 0 0 0 in 1 st clock ->0 0 0 0 in 2nd clock -> 1 0 0 0.

Arjun said: (Feb 6, 2017)  

I can't understand your solution. Please explain it clearly.

Lekshmi said: (Nov 8, 2017)  

Please explain the third clock pulse o/p and fourth clock pulse o/p.

Narasimha said: (Nov 20, 2017)  
It's very simple.

Initially, assume 0000 in the register. The Question says that out of 0010, they first perform 0 bit followed by 1. Let's see, after 1st clock pulse, the output display as 0*000. Then after second clock pulse, the output display as 1*000.

So, our answer is 1000.

* means TRANSMITTED/Shifted BIT.

Gurumalar said: (Sep 12, 2018)  
In 4bit parallel shift registers the values are <9 we should add0110. So,
0010+0110 = 1000.

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