The flip-flop

The flip-flop

The flip-flop is a device that can be in one of two states: set or reset. The flip-flop we show here has two inputs: the lower one sets the flip-flop and the upper one resets it. The flip-flop emits a steady stream of ones while it it set.

set-reset flip-flop

In the design above, the state of the flip-flop is stored in the small loop in the middle. The loop is six cells long, and an electron continuously circulates round this loop while the flip-flop is set.

The bottom of the loop is merged with an OR gate. The spare input to the gate is the set signal: the set signal is thus ORed into the state of the loop. At the top of the loop is an AND-NOT gate (simpler version). A suitably timed pulse on the top input to this gate will remove the electron from the loop. The example above shows the flip-flop being set (on generation 6 or thereabouts) and cleared three bit-times later (at about generation 24). The flip-flop emits a stream of four electrons during this period.

The output of the flip-flop can be taken from any suitable point on the loop.

This design of flip-flop is the main reason for our choice of 6-micron technology. A loop of length 5 can’t be made (try it!); most of the logic elements do not work at 4 microns; and so 6 is the smallest reasonable size to use.

Next: a binary adder.

<Previous page  Wireworld index  Next page>


This page most recently updated Mon 16 Jan 11:10:09 GMT 2017
Word Matcher

Options...
Type a pattern, e.g.
h???o
into the box and click ‘Go!’ to see a list of matching words. More...


Qxw screen
Qxw is a free (GPL) crossword construction program. Answer treatments, circular and hex grids, jumbled entries, more besides. Release 20140331 for both Linux and Windows. More...

Practical Signal Processing front cover
My book, ‘Practical Signal Processing’, is published by Cambridge University Press. You can order it directly from them, or via amazon.co.uk or amazon.com. Paperback edition now also available. Browse before you buy at Google Books. Wydanie polskie.

If you find this site useful or diverting, please consider a donation to NASS (a UK registered charity), to KickAS (in the US), or to a similar body in your own country.

Copyright ©2004–17.
All trademarks used are hereby acknowledged.