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.





 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.



 3. The functionality of each gate can be described using a ________________

  logic gate correlation

  mathematical formula that uses brackets

  alegebraic expression

  truth table

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





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





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





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





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

  at least two


  at least one


 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)





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



 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

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

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

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

  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.

  binary sequences

  ASCII values



 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

  binary bits - that are the building blocks of computers

  small CPU chips - brains of any machine

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



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