Introduction:
Half Adder-
The half adder circuit is required to add two input digits (for Ex. A and B) and generate a-
carry and sum. The half adder adds two binary digits called as agenda and addend and
produces two outputs as sum and carry (XOR is applied to both inputs to produce sum and
AND gate is applied to both inputs to produce carry). It means half adder circuits can add
only two digits in other words if we need to add more than 2 digits it will not work, so, it the
limitation of an half adder electronic circuits. To resolve this problem a full adder circuit is
required.
Full Adder-
A full adder logic circuit has three inputs A, B and C, which add the three input numbers
and generate a carry and sum. The full adder adds 3 one bit numbers, where two can be
referred to as operands and one can be referred to as bit carried in. And produces 2-bit
output, and these can be referred to as output carry and sum. The difference between a
half-adder and a full- adder is that the full-adder has three inputs and two outputs,
whereas half adder has only two inputs and two outputs. When full-adder logic is designed,
you string eight of them together to create a byte-wide adder and cascade the carry bit from
one adder to the next. Figure given below show the logic circuits of Half adder and Full
adde
Objective:
▪ The main objectives of this experiment are:
▪ To construct and test various adder circuits.
▪ To construct and test various subtractor circuits.
▪ To construct and test a magnitude comparator circuit.
Components
▪ IC trainer Kit
▪ IC type 7486 quad 2-input XOR gates
▪ IC type 7408 quad 2-input AND gates
▪ IC type 7404 HEX inverter
▪ IC type 7483 4-bit binary adder
▪ IC type 7485 4-bit magnitude comparator.
Background:
Half Adder and Full Adder are basic element of Digital electronics, which is used for
arithmetic functionality in digital circuits. They will be used to make binary addition and
thus, they are basic building blocks for designing more complex arithmetic circuits like in
microprocessors and digital calculators.
Result:
Comment:
In this lab, we connected the half adder using two types of IC and got two types of input
and two types of output. As for the full adder, we connected it using only one bit and used
IC 7483. Then we connected the full adder using 4 bits, then we connected the subtractor
adder and recorded the outputs for sum and carry c0. Then we used IC 7485 to compare
tow 4-bit for A and B, and recorded the results.
Conclusion:
This lab focused on the design and operation of Half Adders and Full Adders used to
implement the binary addition in digital systems. Half Adder: A simple and fundamental
logic circuit that adds two single-bit numbers together, producing a sum output and carries
output. But it can not accept carry input from previous stage and this limitation is
corrected by Full Adder. On the other hand, Full Adder accepts three inputs which are two
important bits and carry in, and generates two outputs: sum and carry out. Hence we can
use Full Adder in multiple bit addition making it more versatile, Full Adders are basically
used for binary adders as well in processors.
Questions:
