Chapter 4 Computer Science
What is the output value of an OR gate when both inputs are 1?
1
what is a transistor made of?
a semiconductor material
circuits used for memory are what type of circuits?
memory circuits are sequential circuits because they are dependent on the existing state of the circuit as well as input to the circuit
how many digits does an S-R latch store?
one binary digit
What does the NOR operation do?
only produces a true if all inputs are false
What does the NAND operation do?
only produces false if all inputs are true
What does the XOR operation do?
produces a 0 only if all inputs are 0, and a 1 only if all inputs are 1
What does the AND operation do?
produces a 1 only if all its inputs are 1
What does the OR operation do?
produces a 1 only if one of the inputs is 1
what is the boolean expression for the NAND gate?
same as AND, but with a line over the top
what is the boolean expression for the NOR gate?
same as OR, but with a line over the top
what are sequential circuits?
circuits in which the output is a function of input values and the current state of the circuit
what is SSI (small scale integration)?
contains 1 to 10 gates
what MSI (medium scale integration)?
contains 10 to 100 gates
what is LSI (large scale integration)?
contains 100 to 100,000 gates
what is VLSI (very large scale integration)?
contains more than 100,000 gates
what are truth tables in terms of gates and circuits?
define the behavior of gates and circuits by showing all possible input and output combinations of the gates and circuits
how many output signals can a gate produce?
a gate can only produce one output value
Can a gate be designed to accept more than 2 inputs?
yes
What is the compliment property?
(A AND (A') = 0) (A OR (A') = 1)
what is the identity property?
(A AND 1 = A; A OR 0 = A)
What is Demorgan's Law?
(A AND B)' = A' OR B' (A OR B)' = A' AND B'
How can the XOR operation be expressed using other operators?
(A OR B) AND (NOT (A AND B))
How many transistors does it take for the NOT gate?
1
What is the output value of an OR gate when one value is 1 and the other is 0?
1
what is the output of an AND gate when both inputs are 1?
1
What are the three notational methods for desribing the behavior of gates and circuits?
1) Boolean expressions 2) Logic diagrams 3) Truth tables
What are the six types of gates?
1) NOT 2) AND 3) OR 4) NAND 5) NOR 6) XOR
What are the two general categories of circuits?
1) combinational circuits 2) sequential circuits
What are the six properties of boolean algebra?
1) commutative 2) associative 3) distributive 4) identity 5) compliment 6)DeMorgan's Law
What are the three terminals in a transistor?
1) source 2) base 3) ground (emitter)
How many transistors does it take for the AND gate?
2
How many transistors does it take for the XOR gate?
8
what are pins used for?
8 are used for inputs to gates, four for outputs from the gates, one for ground, and one for power
How many transistors does it take for the NOR gate?
How many transistors does it take for the OR gate?
what is the reationship between the NAND and the AND gate?
The 2 outputs are inverses of one another
What is the boolean expression for the XOR gate?
X = A (circle with the plus sign) B
what is the boolean expression for an AND gate?
X = A * B
What is the boolean expression for an OR gate?
X = A + B
what is the boolean expression for the NOT gate?
X = A'
what is a full adder?
a circuit that computers the sum of 2 bits, taking into account the carry bit
what is a half adder?
a circuit that computes the sum of two bits and produces the appropriate carry bit
What is a multiplexer?
a circuit that uses input control signals to determine which of several date input lines is to be routed to the output
how many input signals can a gate receive?
a gate can accept one or more input signals
what is used in a gate to establish how the input values map to the output value?
a transistor
what is a base in terms of a transistor?
a value that regulates a gate that determines whether the connection between the source and the ground is made
how is voltage level used to distinguish between binary digits?
a voltage level in the range of 0 to 2 volts is is interpreted as binary 0. A voltage level in the range of 3 to 5 volts is interpreted as a binary 1.
what is a source in terms of a transistor?
an electric signal
what is a CPU?
an integrated circuit
what is an integrated circuit or chip?
an integrated circuit or chip is a piece of silicon into which many gates have been embedded
How do the three terminals on a transistor operate?
an output line is usually connected to the source. If the base value is high, the source is grounded and the output is low (representing 0). If the base is low, the gate is closed, the source is not grounded, and the output is high (representing 1).
What are combinational circuits?
circuits in which the input values explicitly determine the output
how does a transistor behave?
depending on the voltage of an input signal, a transistor either acts as a wire that conducts electricity or as a resister that blocks the flow of electricity
logic diagrams and truth tables
equally powerful in expressing the processing of gates and circuits
how can gates be combined into circuits?
gates are combined into circuits by using the output of one gate as the input for another. Also the same input value can be used as input to two different gates
what happens when an electrical signal is grounded?
if an electrical signal is grounded, the signal flows through an alternative route to the ground where it can do no harm. When a signal is grounded it is pulled down to 0 volts.
What is Demorgan's law?
inverting the output if an AND gate is equivalent to inverting the individual signs first, then passing them through an OR gate
What does the NOT operation do?
inverts its inputs
what is a gate?
it accepts one or more input signals and produces one output signal. Each type of gate performs one logical function.
what is a circuit?
it is a combination of gates designed to accomplish a more complex logical function.
What does a full adder take into account?
the carry-in value
What are integrated circuits classified by?
the number of gates contained in them
what is the truth table for the NOT gate?
this inverts the input and spits that out for the output
What is the commutative property?
this says that addition problems may be applied the same way from right to left; (A + B) === (B + A)
what is the distributive property?
this says that given three boolean values, ; (A AND (B OR C)) === (A AND B) OR (A AND C) as well as (A OR (B AND C)) === (A OR B) AND (A OR C) can also be seen as (A + (B * C)) === ((A + B) * (A * C)) (A * (B + C) === (A * B) + (A * C))
what is the associative property?
this says that given three boolean variables, the order also does not matter; (A + B) + C === A = (B + C)
what is a transistor made of?
transistors are made of semiconductor material, which is neither a good conductor of electricity nor a particularly good insulator. Transistors are usually made from silicon
what is a logic diagram in terms of gates and circuits?
use a graphical representaion to describe the behavior of gates and circuits
what is a boolean expression in terms of gates and circuits?
uses the operations of boolean algebra to describe the behavior of gates and circuits
what is circuit equivalence?
when two circuits produce the same output from the same input value combination
