Basic Theory:
The
binary incrementer increases the value stored in a register by ‘1’. For this,
it simply adds ‘1’ to the existing value stored in a register. It is made by
cascading ‘n’ half adders for ‘n’ number of bits i.e. the storage capacity of
the register to be incremented. Hence, a 4-bit binary incrementer requires 4
cascaded half adder circuits.
Circuit Diagram:
Observed Values:
Following
set of values were obtained in observation.
1. 0011 => 0100
2. 1010 => 1011
3. 1101 => 1110
4. 0010 => 0011
5. 1111 => 0000; Cout = 1
1. 0011 => 0100
2. 1010 => 1011
3. 1101 => 1110
4. 0010 => 0011
5. 1111 => 0000; Cout = 1
Reference:
Gamezero.com
(n.d.), Designing and Building our 4-bit Addition Engine, Processor Design, Accessed: February 15, 2013, Retrieved from: http://www.gamezero.com/team-0/articles/math_magic/micro/stage1.html
Please can you tell me that how can we design a 4 bit binary incrementer using full adder?
ReplyDeleteUsing a full adder is not necessary, as you can see it works perfectly with half-adders. But it is interesting to think about such an implementation. Full adder has two outputs, and a binary incrementer has just one. So, how will they be cascaded to produce a single output is the main question.
DeleteF.A consists of 3 inputs, A, B, carry_in .just give input to one of the two inputs(A or B) and let other number be zero. the carry_out part should be connected to the carry_in of the next F.A. give logic 1 to the carry_in of first half adder and you are good to go.
DeleteWhat are the A_ and I_ supposed to be? I know the far right line is the last output, and I am assuming that the logic high is just always 1.
ReplyDeleteTo make things a bit clearer: The A inputs A0 to A3 are the number you put in, with A0 being the least significant digit. I0 to A3 are the outputs, equal to A + 1. I0 is again least significant. Carry out can be tied to Logic high of the next 4bit incrementer if multiple are used for larger numbers, but the first adder (and shown here the only one), it needs to be high.
ReplyDeletenice
ReplyDelete