Digital Logic Tutorial

The D Flip Flop

Computers use only two numbers: 0 and 1, which are represented by on or off on a single wire. The RS Flip Flop can't really remember the state of a single wire; it uses two different wires and remembers which one was pressed last.

Here we show the D Flip Flop which is really a bit of digital memory. It has one "D" or Data wire and a "CLK" or clock wire which causes the state of the D wire to be remembered.

If you can't see the simulation below, try this HTML version of the Falstad simulator: D Flip Flop

Digital logic builds, from the absurdly simple to the massively complex. The trick is to make the simple circuit into a block, or module, that you can use to build more complex circuits. The circuit on this page is shown as one of those "stackable" blocks at the bottom of the simulation. The box there contains the circuit at the top of the page. It has inputs and outputs which connect to the NAND gates inside the block or module, as it's called in LogicSim.

Advanced

Notice that the RS Flip Flop is actually still in there: We actually just added a "NOT D" line from the "D" line and made the clock line necessary for either of those to pass.

Next: The 4 bit Register, or Binary and Decimal Numbers

Also:

• Memory

Comments:

See also:

• http://www.instructables.com/id/DIY-RAM-Memory-Register-Style/?ALLSTEPS For those with electronics experience: Here are 3 D type flip flops built from transistors and resistors.+

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