Topic 8 - Logic gates

What is a computer basically made of?

a collection of transistors and circuits.

In basic electronics, what does the "on" state of a component mean?

a current is flowing through the component

In basic electronics, what does the "off" state of a component mean?

a current is not flowing through the component

What binary value represents the "on" (TRUE) state in a computer component?

1

What binary value represents the "off" (FALSE) state in a computer component?

0

What does a logic circuit do?

makes decisions – it receives two or more inputs and determines the output from the inputs.

What is digital logic based on?

digital switches called logic gates.

What binary digit represents true, on, or high?

1

What binary digit represents false, off, or low?

0

What is a logic gate?

an electronic circuit in a device that enables a digital system to make a decision based the inputs.

How many inputs and outputs are usually present in a logic gate circuit?

two inputs to the circuit and one output.

What state is represented by 1 in a logic gate?

on or high

What state is represented by 0 in a logic gate?

off or low

What does a truth table show?

the logic rules of a logic gate.

What does a truth table list?

all combinations of input values and the resulting output.

When will an AND gate give a TRUE output?

Only if all of the inputs are TRUE.

What is the output of an AND gate except when both inputs are 1?

The output is always 0 (or FALSE).

In elevator systems, when can the output of an AND gate be TRUE?

Only when both the doors closed is TRUE (one input) and the "floor selected" button is TRUE

When will an OR gate give a TRUE output?

If either of the inputs is TRUE.

What is the output of an OR gate except when two inputs are 0?

The output is always 1 (or TRUE).

In a home security system using an OR gate, when will the alarm sound?

if the burglar breaks in through the window OR the front door.

How many inputs does a NOT gate have?

Only one input.

When will a NOT gate give a high output?

If the input is low (or 0).

What is a NOT gate used for in most traffic lights?

to make sure the red light and green can never ben shown together in any sequence.

What is a NAND gate?

A NOT-AND gate, which is equivalent to an AND gate followed directly by a NOT gate.

What is a NOR gate?

A NOT-OR gate, which is equivalent to an OR gate followed directly by a NOT gate.

When is the output of a NOR gate high (1)?

If both inputs are low (or 0).

What does an XOR gate compare and generate?

It compares two input bits and generates one output bit.

In an XOR gate, what is the result if the bits are the same?

0 (or FALSE).

In an XOR gate, what is the result if the bits are different?

1 (or TRUE).

What is XOR often referred to as?

exclusive OR

Where is XOR often used?

cryptography

What can be used to produce a complex logic system in a device such as a burglar alarm?

A combination of different logic gates

How are logic gates used in game design?

to create complex behaviours and decision-making processes for non-player characters.

What do logic gates contribute to in video games?

the artificial intelligence in video games.

What is the logic sign/operator for an AND gate?

What is the logic sign/operator for an OR gate?

Plus or Disjunction.

What is the logic sign/operator for a NOT gate?

Overline (Bar) or Negation.

What is the logic sign/operator for a NAND gate?

Overlined Dot or Negated Conjunction.

What is the logic sign/operator for a NOR gate?

Overlined Plus or Negated Disjunction.

What is the logic sign/operator for an XOR gate?

Circle Plus or Exclusive OR.