Stephen M. Webb
stephenw at xandros.com
Mon Mar 21 10:31:04 EST 2005
On 20/03/05 11:29 pm, Jeff 'Alias' East wrote:
> On Sun, Mar 20, 2005 at 11:11:30PM -0500, Frank Stratton - VE3YY wrote:
> > This is a true story!
> > At one time believe it or not, a computer manufacturer I worked for, was
> > looking into having a piece of memory represent three states, zero, one
> > and not (zero or one). Memory was so expensive when I was first around
> > computers
> I was learning about tri-state chips a few years back, and the same
> thought occured to me. I called it "Trinary".
Ternary logic is a frequent occurrence in computers. Some examples:
o tri-state behaviour of various devices on a bus (high, low, not-on-bus).
This includes memory as well as ISA, PCI, and USB buses.
o SQL uses ternary logic frequently. For example, a boolean column in a
table might have the values true, false, or null. One of the first things
you used to have to do (and I don't know if things have changed over the
decades) when learning SQL was to master the ternary logic of query values.
o The C programming languages uses ternary logic frequently. A lack of
understanding of its ternary logic is a main cause of buffer overrun expoits.
The list goes on, but ternary logic is certainly nothing special. I even use
it with my kids and they understand it. ("yes", "no", "go ask your mother").
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