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02 - Truth tables and logic circuits

 1. The concept may be confusing at first but all digital circuits are created using a combination of logic _______________ 
Learning note: Electronic gates require a power supply.
Gate INPUTS are driven by voltages having two nominal values, e.g. 0V and 5V representing logic 0 and logic 1 respectively.
The OUTPUT of a gate provides two nominal values of voltage only, e.g. 0V and 5V representing logic 0 and logic 1 respectively. In general, there is only one output to a logic gate except in some special cases.
There is always a time delay between an input being applied and the output responding.

  CPUs

  bulbs

  gates

  mates

 2. Digital systems are said to be constructed by using logic gates. These gates are the AND, OR, NOT, NAND, NOR, EXOR and EXNOR gates.
allgates.png

  FALSE

  TRUE

 3. The functionality of each gate can be described using a ________________ 
The structure used to represent the boolean expression 
of a logic gate function is commonly called a ___________.

A logic gate ____________shows each possible input combination
to the gate or circuit with the resultant output depending upon
the combination of these input(s).

  mathematical formula that uses brackets

  truth table

  binary expression

  logic gate correlation

 4. The following gate is an '_______' gate.
andgate.gif

  NOT

  NAND

  OR

  AND

 5. The following gate is an '_______' gate.
orgate.gif

  AND

  OR

  NAND

  NOT

 6. The following gate is an '_______' gate.
notgate.gif

  NOT

  OR

  NAND

  AND

 7. The AND gate is an electrical circuit that gives an output of ____ only if all of its inputs are also _____.

  3

  2

  1

  0

 8. The OR gate is an electrical circuit that gives an output of a 1 if_______________ of its inputs are a 1.

  none

  at least two

  at least one

  all

 9. The NOT gate is an electrical circuit that produces an _______ version of the input as the output. (e.g. a 1 will be a 0)

  inverted

  positive

  converted

  negative

 10. If the input into a NOT gate is a 0 the output will also be a 0.

  FALSE

  TRUE

 11. A truth table can show the operations (with inputs and outputs) of any given gates. The following shows the truth table for the ________ 
2 Input truth table for an ____gate
======================
A      B      Output
------------------------
0       0            0
0       1            0                                   1       0            0       
1       1            1

  NOT Gate - because the output is always the inversion (opposite) of what is in A or B

  And Gate because both inputs (A and B) need to be 1 in order for the output to be 1

  Or Gate because when either A or B inputs are 1 the output is 1

  This truth table is incorrect and doesn't describe any gate

 12. Logic gates are electronic circuits that manipulate _______ or in effect manipulate the binary 1s and 0s that are inside your computer.

  voltages

  ASCII values

  binary sequences

  waves

 13. The ENIAC is widely thought to be the first ever electronic general purpose computer. These sort of computers had hundreds of ___________________________________ 
______ can also be thought of as special types of switch. _____ can be in one of two states: on or off.

  valves - that are electric current amplifiers

  microscopic atomic cells - that allow for storage

  small CPU chips - brains of any machine

  binary bits - that are the building blocks of computers

 14. One of the problems with valves is that they were bulky, burned out easily and weren't terribly efficient. (as compared to transistors)

  FALSE

  TRUE

 15. Transistors were much much larger than valves and were therefore much more efficient and powerful.

  FALSE

  TRUE


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