Chapter 4--gates & Circuits Flashcards
True/False. Inverting the output of an AND gate is the same as inverting the individual signals first, and then sending them through an OR gate.
true. DeMorgan’s Law.
What voltages produce 0 and 1 in a logic board, respectively?
0-2 volts is a zero, and 2-5 volts is a one.
True/False. A multiplexer adds all of the bits on its input lines to produce an output.
false. it selects the inputs to use based on control lines. called “select signals” or “select control lines.”
what are the types of integrated circuits, and how are those types defined?
SSI=small-scale integration=1 to 10 gates. MSI=medium-scale integration=10 to 100 gates. LSI=large-scale integration=100 to 100K gates. VLSI=very-large-scale integration=100K+ gates
What’s the difference between a gate and a curcuit?
a circuit is a combination of several gates
how does a transistor behave?
as a wire or as a resistor, depending on the input signal
what is a transistor made of?
silicon doped with rare-earth element impurities
what are the 3 terminals in a transistor, & how do they operate?
source–produces a high voltage value, about 5 volts. Base–regulates a gate that determines whether the connection between source and ground/emitter is made. emitter–is connected to the ground wire.
what are the two categories of circuits, and how do they differ?
Combinatorial and sequential. in a combinatorial circuit, the input values explicitly determine the output. In a sequential circuit the output is determined by both the input values and the existing state of the circuit.
How many transistors does it take for each of these gates: NOT, NAND, AND, NOR, OR, & XOR?
NOT=1, NAND=2, AND=3, NOR=2, XOR=8, OR=2
name six properties of Boolean algebra, and explain each one.
1.commutative property=says that binary operations
AND and OR may be applied left to right or right to left. (AB=BA, a+b=b+a)
2.The associative property says that given three Boolean variables, they may be ANDed or ORed right to left or left to right. ((AB)C=A(BC); (a+b)+c=a+(b+c)). remember OR=the plus sign
- The distributive property says that given three Boolean variables. the first AND the result of the second OR the third is the same as the first AND the second OR the first AND the third. ( A(B+C) = (AB)+(AC)) Also, the first OR the result of second AND the third is the same as the first OR the second
AND the result of the first OR the third. (A+(BC) = (A+B)*(A+C) - The identity property says that any value A AND the OR identity always returns A and that any value A OR the AND identity always returns A. (A*1 = A; A+0 = A)
- The compliment property says that any value AND the compliment of that value equals the OR identity and that any value OR the compliment of that value equals the OR identity. (A*(A’)= 0; A+(A’) = 1)
- DeMorgan’s Law says that the compliment of AB is the same as the compliment of A plus the compliment of B and the compliment of A+B is the same as the compliment of B times the the compliment of A. ((AB)’ = A’+B’; (A+B)’ = A’*B’)
compare half-adder and full adder.
A half adder is a circuit that computes the sum of two bits and produces the appropriate carry bit. A full adder is a circuit that computes the sum of two bits, taking into account the carry bit.
define “multiplexer”.
a circuit that uses input control signals to determine
which of the data input lines is to be routed to the output.
give the Boolean expression for a full adder.
C is the carry in.
Sum is (A ⊕ B) ⊕ C)
Carry out is (AB) + ((A ⊕ B)C)
circuits used for memory are what type of circuit?
memory circuits
