Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #69397

Re: checking if two things do not equal None

Show key headers only | View raw

Roy Smith wrote:
> Adding to the 
> confusion, many designs would use "active low" logic, which means a 1 
> was represented by a low voltage, and a 0 by a high voltage.  So, you 
> quickly end up with gibberish like, "not active low clear nand not 
> active low enable clock".

There are ways of dealing with that in schematic diagrams.
For exammple, if you have two active-low signals A and B
and want to express "A is active or B is active", you
draw an OR gate symbol with inversion circles on the
inputs. That's equivalent to a NAND gate, but makes the
intention clear.

Schematics drawn that way are much easier to follow than
ones that only use the inverted-output versions of the
symbols.

-- 
Greg

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

checking if two things do not equal None contact.trigon@gmail.com - 2014-03-29 11:56 -0700
  Re: checking if two things do not equal None Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-29 19:05 +0000
    Re: checking if two things do not equal None contact.trigon@gmail.com - 2014-03-29 12:23 -0700
    Re: checking if two things do not equal None Lele Gaifax <lele@metapensiero.it> - 2014-03-29 20:24 +0100
    Re: checking if two things do not equal None Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-03-29 22:01 +0100
      Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-29 17:07 -0400
        Re: checking if two things do not equal None Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-03-29 22:55 +0100
          Re: checking if two things do not equal None Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-03-29 23:02 +0100
        Re: checking if two things do not equal None Dave Angel <davea@davea.name> - 2014-03-29 18:01 -0400
          Re: checking if two things do not equal None contact.trigon@gmail.com - 2014-03-29 16:20 -0700
        Re: checking if two things do not equal None Tim Chase <python.list@tim.thechases.com> - 2014-03-29 17:36 -0500
          Re: checking if two things do not equal None Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-30 02:24 +0000
            Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-29 22:43 -0400
              Re: checking if two things do not equal None Zachary Ware <zachary.ware+pylist@gmail.com> - 2014-03-29 22:04 -0500
        Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-29 18:41 -0400
        Re: checking if two things do not equal None Tim Chase <tim@thechases.com> - 2014-03-29 17:46 -0500
          Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-29 18:51 -0400
        Re: checking if two things do not equal None Chris Angelico <rosuav@gmail.com> - 2014-03-30 10:17 +1100
        Re: checking if two things do not equal None Tim Chase <python.list@tim.thechases.com> - 2014-03-29 20:19 -0500
        Re: checking if two things do not equal None Chris Angelico <rosuav@gmail.com> - 2014-03-30 12:37 +1100
        Re: checking if two things do not equal None Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-30 02:04 +0000
          Re: checking if two things do not equal None Chris Angelico <rosuav@gmail.com> - 2014-03-30 13:15 +1100
            Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-29 22:39 -0400
              Re: checking if two things do not equal None Rustom Mody <rustompmody@gmail.com> - 2014-03-29 19:54 -0700
                Re: checking if two things do not equal None Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-30 06:08 +0000
                Re: checking if two things do not equal None Roy Smith <roy@panix.com> - 2014-03-30 08:21 -0400
                Re: checking if two things do not equal None MRAB <python@mrabarnett.plus.com> - 2014-03-30 14:58 +0100
                Re: checking if two things do not equal None Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-31 11:48 +1300
              Re: checking if two things do not equal None Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-03-30 19:41 +1300
                Re: checking if two things do not equal None Marko Rauhamaa <marko@pacujo.net> - 2014-03-30 10:37 +0300
            Re: checking if two things do not equal None Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-03-30 05:54 +0000
              Re: checking if two things do not equal None Chris Angelico <rosuav@gmail.com> - 2014-03-30 17:17 +1100
              Re: checking if two things do not equal None Ben Finney <ben+python@benfinney.id.au> - 2014-03-30 17:52 +1100
              Re: checking if two things do not equal None Chris Angelico <rosuav@gmail.com> - 2014-03-30 18:36 +1100
      Re: checking if two things do not equal None Ethan Furman <ethan@stoneleaf.us> - 2014-03-29 16:20 -0700
  Re: checking if two things do not equal None Terry Reedy <tjreedy@udel.edu> - 2014-03-29 19:02 -0400
  Re: checking if two things do not equal None Jeremy Sanders <jeremy@jeremysanders.net> - 2014-03-31 09:56 +0200
    Re: checking if two things do not equal None Abe <contact.trigon@gmail.com> - 2014-03-31 10:28 -0700
      Re: checking if two things do not equal None Moritz Emanuel Beber <moritz.beber@gmail.com> - 2014-03-31 21:22 +0200

csiph-web