Write an expression for borrow and
difference in a full subtractor circuit.
2 Draw the circuits diagram for 4-bit odd parity generator.
3. Design a single bit magnitude comparator to compare two words A and B.
4 What is an encoder?
An encoder has 2n input lines and n output lines. In encoder the output lines generate the binary code corresponding to the input value.
5 List few applications of multiplexer.
· Data Selector.
· Implement combinational logic circuit.
· Time multiplexing systems
· Frequency multiplexing systems.
· D/A and A/D converter
· Data acquisition systems.
6 Design a half subtractor using basic gates.
7 Draw the logic diagram of a 4 line to 1 line multiplexer.
8 What is priority Encoder?
A priority encoder is an encoder circuit that includes the priority function. In priority encoder, if 2 or more inputs are equal to 1 at the same time, the input having the highest priority will take precedence.
9 Write down the difference between demultiplexer and decoder.
10 Give the logic expression for sum and carry in full adder circuit.
Sum= (A⊕B)⊕Cin Carry=AB+BCin+A Cin
11 Give examples for combinational circuit.
12 Draw the logic circuit of a 2-bit comparator.
13 Suggest a solution to overcome the limitation on the speed of an adder.
It is possible to increase speed of adder by eliminating inter-stage carry delay. This method utilizes logic gates to look at the lower-order bits of the augend and addend to see if a higher-order carry is to be generated.
14 Relate carry generate, Carry propagate, Sum and Carry-out of a Carry look a head adder.
15 Realize the Boolean function using appropriate multiplexer F(A,B,C)= Σ (0,1,3,7)
16 Compare the performance of binary serial and parallel adders.
· Serial adder uses shift registers
· The serial adder requires only one full adder circuit
· The serial adder is a sequential circuit
· Time required for addition depends on the number of bits
· It is slower
· Parallel adder uses registers with parallel load capacity
· It is faster
· Time required for addition does not depend on number of bits
· Excluding the registers, the parallel adder is a purely combinational circuit
17 Design of three bit parity generator.
Odd parity generator:
18 Draw the logic diagram of serial adder.
19 Construct a two-4-bit parallel adder/subtractor using Full Adders and XOR gates.
20 Convert a two-to-four line decoder with enable input to 1X4 Demultiplexer.