1.The carry look ahead adder is based on the principle of looking at the lower order bits of ________ and ________ if a high order carry is generated.
a) Addend, minuend
b) Minuend, subtrahend
c) Addend, minuend
d) Augend, addend
Explanation: The carry look ahead adder is based on the principle of looking at the lower order bits of the augend and addend if a high order carry is generated. A carry look ahead adder is a type of adder which reduces the propagation delay
2. What are carry generate combinations?
a) If all the input are same then a carry is generated
b) If all of the output are independent of the inputs
c) If all of the input are dependent on the output
d) If all of the output are dependent on the input
Explanation: If the input is either 0, 0, 0 or 0, 0, 1 then the output will be 0 (i.e. independent of input) and if the input is either 1, 1, 0 or 1, 1, 1 then the output is 1 (i.e independent of input). Such situation is known as carry generate combinations.
3. In serial addition, the addition is carried out __________
a) 3 bit per second
b) Byte by byte
c) Bit by bit
d) All bits at the same time
Explanation: In serial addition, the addition is carried out bit by bit.
4. How many shift registers are used in a 4 bit serial adder?
a) 4
b) 3
c) 2
d) 5
Explanation: There are two shift registers are used in a 4-bit serial adder, which is used to store the numbers to be added serially. Serial addition takes place bit by bit
5. A D flip-flop is used in a 4-bit serial adder, why?
a) It is used to invert the input of the full adder
b) It is used to store the output of the full adder
c) It is used to store the carry output of the full adder
d) It is used to store the sum output of the full adder
Explanation: The D flip-flop, i.e. carry flip-flop, is used to store the carry output of the full adder so that it can be added to the next significant position of the numbers in the registers
6. What is ripple carry adder?
a) The carry output of the lower order stage is connected to the carry input of the next higher order stage
b) The carry input of the lower order stage is connected to the carry output of the next higher order stage
c) The carry output of the higher order stage is connected to the carry input of the next lower order stage
d) The carry input of the higher order stage is connected to the carry output of the lower order stage
Explanation: When the carry output of the lower order stage is connected to the carry input of the next higher order stage, such types of connection is called ripple carry adder in a 4-bit binary parallel adder
7. If minuend = 0, subtrahend = 1 and borrow input = 1 in a full subtractor then the borrow output will be __________
a) 0
b) 1
c) Floating
d) High Impedance
Explanation: If minuend = 0, subtrahend = 1 and borrow input = 1 in a full subtractor then the borrow output will be 1. Because on subtracting 0 and 1, one borrow is taken and it proceeds till the next step (i.e 0 – 1 – 1 = 0, borrow = 1)
8. The decimal number system represents the decimal number in the form of ____________
a) Hexadecimal
b) Binary coded
c) Octal
d) Decimal
Explanation: Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Hexadecimal and Octal are number systems having base 16 and 8 respectively
9. 29 input circuit will have total of ____________
a) 32 entries
b) 128 entries
c) 256 entries
d) 512 entries
Explanation: 29 input circuit would have 512(2*2*2*2*2*2*2*2*2 = 512) entries.
10.BCD adder can be constructed with 3 IC packages each of ____________
a) 2 bits
b) 3 bits
c) 4 bits
d) 5 bits
Explanation: Binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. BCD adder can be constructed with 3 IC packages. Each of 4-bit adders is an MSI(Medium scale Integration) function and 3 gates for the correction logic need one SSI (Small Scale Integration) package.