[sdiy] Finding the correct IC...

[Scott Gravenhorst]

media.nai at rcn.com wrote:
>At 9:43 PM +0100 06/19/02, Neil Johnson wrote:
>>> >D is for "Data"
>>>
>>> Not according to the logic textbook I have.
>>
>>I just checked in mine:
>>
>>Logic Designer's Manual, John D. Lenk, 1977
>>  "D-type flip-flop ... requires only one data input in addition to the
>>clock input" ...and the schematic diagram is courtesy of Honeywell.
>
>Where does that say "D" stands for "data"??  Besides, "data" isn't much of
>a distinction among flip-flops.  It's all data if it stands for something :)
>
>"Another flip-flop available in an integrated circuit form is the clocked D
>(delay) flip-flop..."
>_Fundamentals of Logic Design_, Charles H. Roth, Jr (1975, 1992).
>
>The same book also lists it as "Delay" in a table entitled "Determination
>of Flip Flop Input Equations..."

I think it matters less what the D stands for (to me, it's "data"), but
rather that we all agree what a D flipflop is and does.  

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.  Whether the surrounding logic
implements a delay of transfer of that data is irrelevant.  Whatever "data"
is at the D input at clock time gets transferred to and is held at the Q output.

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.

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