COMP 1003 FINAL QUESTIONS AND VERIFIED
ANSWERS
What is a half-adder and how does it work? - Answers - A half adder is a basic digital
circuit capable of adding two bits together. The half-adder has two outputs; the sum,
which is the XOR of the two bits, and the carry, which is the AND of the two bits. The
Half-adder does not take the "carry in" into account.
What is a full-adder and how does it work? - Answers - The full-adder is capable of
adding two bits together, as well as using a third "carry-in" input, that represents the
carry from the previous stage of addition. The full-adder has two outputs; the sum,
which is a XOR of all three inputs (A XOR B XOR Cin), and the carry out, which is
considers if two or more of the input variables are 1: (A AND B) OR (Cin AND (A XOR
B)
What is a decoder? - Answers - A decoder uses a combination of input values to select
one specific output line. Typically used to address specific memory systems or selecting
which functions to use based upon input. A decoder that has n input lines will have 2^n
output lines
What is a multiplexer? - Answers - A multiplexer selecta a single output from multiple
inputs. Differing from the decoder, the multiplexer not only accepts input values, but it
accepts "control lines", an additional set of input values. If a multiplexer has m control
lines, it can select one of 2^m input channels.
What is an ALU? - Answers - An ALU (Arithmetic Logic Unit) is a component of the
central processing unit, and is responsible for performing arithmetic and logical
operations on binary numbers.
What is Set/Reset Flip/Flop? - Answers - SR Flip/Flop is a basic unit of memory where
no signal set (S=0 and R=0) will leave Q in its current state, (S=1 and R=0) will set Q to
1, and (S=0 and R=1) will set Q to 0, where Q is referring to the output. If (S=1 and
R=1) Q is undefined. When we speak of SR Flip/Flop, we are usually referring to a
clocked version, where the input is timed for when the clock pulses.
What is a JK Flip/Flop? - Answers - A JK Flip/Flop adds stability for when (S=1 and
R=1), as it will produce Q', the inverse of the current state of Q
What is a D Flip/Flop? - Answers - Accepts a single input value, denoted as D. Q, the
output, only changes according to D; if D=1, then Q=1. It is a true representation of
physical computer memory.
What is a synchronous counter? - Answers - A synchronous counter is a type of digital
counter that uses a clock signal to synchronize all of the inputs of a systems flip/flops.
ANSWERS
What is a half-adder and how does it work? - Answers - A half adder is a basic digital
circuit capable of adding two bits together. The half-adder has two outputs; the sum,
which is the XOR of the two bits, and the carry, which is the AND of the two bits. The
Half-adder does not take the "carry in" into account.
What is a full-adder and how does it work? - Answers - The full-adder is capable of
adding two bits together, as well as using a third "carry-in" input, that represents the
carry from the previous stage of addition. The full-adder has two outputs; the sum,
which is a XOR of all three inputs (A XOR B XOR Cin), and the carry out, which is
considers if two or more of the input variables are 1: (A AND B) OR (Cin AND (A XOR
B)
What is a decoder? - Answers - A decoder uses a combination of input values to select
one specific output line. Typically used to address specific memory systems or selecting
which functions to use based upon input. A decoder that has n input lines will have 2^n
output lines
What is a multiplexer? - Answers - A multiplexer selecta a single output from multiple
inputs. Differing from the decoder, the multiplexer not only accepts input values, but it
accepts "control lines", an additional set of input values. If a multiplexer has m control
lines, it can select one of 2^m input channels.
What is an ALU? - Answers - An ALU (Arithmetic Logic Unit) is a component of the
central processing unit, and is responsible for performing arithmetic and logical
operations on binary numbers.
What is Set/Reset Flip/Flop? - Answers - SR Flip/Flop is a basic unit of memory where
no signal set (S=0 and R=0) will leave Q in its current state, (S=1 and R=0) will set Q to
1, and (S=0 and R=1) will set Q to 0, where Q is referring to the output. If (S=1 and
R=1) Q is undefined. When we speak of SR Flip/Flop, we are usually referring to a
clocked version, where the input is timed for when the clock pulses.
What is a JK Flip/Flop? - Answers - A JK Flip/Flop adds stability for when (S=1 and
R=1), as it will produce Q', the inverse of the current state of Q
What is a D Flip/Flop? - Answers - Accepts a single input value, denoted as D. Q, the
output, only changes according to D; if D=1, then Q=1. It is a true representation of
physical computer memory.
What is a synchronous counter? - Answers - A synchronous counter is a type of digital
counter that uses a clock signal to synchronize all of the inputs of a systems flip/flops.
