[sdiy] Finding the correct IC...

[Scott Gravenhorst]

media.nai at rcn.com wrote:
>At 11:11 AM +0000 06/20/02, Scott Gravenhorst wrote:
>>
>>I had been taught a DEC school that it stands for Data, because it's basic
>>purpose is simply to store 1 bit of data.
>
>Isn't that true of every flip-flop??


What is important is to know what the D type flip flop *does*, not 
what the D stands for.  As I said, if you like "delay", fine.  But 
it's probably best to call it a "D flip flop" since that's what 
everyone understands.  You can argue it means "dung" for all I care, 
that does not change what it does in a circuit.

>>Whether the surrounding logic
>>implements a delay of transfer of that data is irrelevant.
>
>It doesn't seem irrelevant considering the other flip-flops that do not
>rely on clock inputs don't do that.

"Delay" is no less ambiguous since a D type is not the
only clocked type.  All clocked flip flops can perform a 
delayed data transfer.  If you say a "delay flip flop", I
don't know if you mean a D, or a JK connected in any number
of ways.  If you say "D Flip Flop", I know exactly what you
mean (which BTW can be a JK connected a certain exact way).

>
>> Whatever "data"
>>is at the D input at clock time gets transferred to and is held at the Q
>>>output.
>
>Right, it's delayed by the clock :)

"Delay" is ambiguous using your own logic.  When talking about it to 
another person, simply referring to it as a D type flipflip is 
unambiguous.  Referring to it as a "Delay" flip flop *is* ambiguous 
since a D type is not the only type that is clocked.  And since texts
differ on the subject, whether D means Data or Delay is irrelevant and
does not change what the device does.

>>So if you like Data, great, if you like Delay, great too, just know
>>what a D flipflop is and what it does and you'll be good to go.

>This is true.

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