what does it mean that nothing will change no function
If Clock = 0 then Q can not change.
>Q=Q Q is stored, can not change, will not change
>D does not change anything. Q=Q, can not change, Nothing happens, No function.
>How do I say 'nothing can happen'.
If Clock = 1 then Q can not change.
>Same as above. Nothing can happen.
If Clock = falling edge then Q can not change.
>Q can not change. No function.
>>>No AND function.
>>>No OR function.
>>>No XOR function.
>>>No Invert (1/x).
>>>Nothing happens. Q=Q No change.
In the above examples D=x. It does not mater what D is.
>>If D=1 or If D=0 all the above is still true.
If Clock =_/ then Q becomes what D is.
>>>This is the only time D can effects Q.
>>>This is the only case where anything happens. This is a function.
D Clk |Q
--------------
0 0 | Q
1 0 | Q
0 1 | Q
1 1 | Q
0 _/| 0
1 _/| 1
Because the top 4 lines have the same results (q=q) then it does not matter what D or Clk are. They can be anything and the same thing happens. (nothing)
D Clk |Q
--------------
x x | Q
I don't know how to tell you Q=Q.
>>If Q=0 before, Then Q=0 after.
>>If Q=1 before, Then Q=1 after.
>>>>>Q=Q
>>>>>Qold=Qnew
>>>>>Q=Qn
This flip flow is "memory". You can write something into memory only on the rising edge of clock.
What is written is D.
Once something is stored it can not be changed (if power is on) until some thing new is written.
The reason I say Q=? is because when you get memory (or a hard drive) you don't know what the person before you wrote in the memory. If you don't know what is in memory then Q=?. Only after you put something known into memory can you say Q=1 or Q=0.