Jon,

The short answer.

Use the value -1 for true instead of 1,2 or anyother value.

NOT -1 = 0
NOT 0 = -1

end of short answer.

Long answer.

Operators like AND, OR, EXCLUSIVE OR, and NOT
can come in two varities.  Logical and bitwise.
Because they react differently you have to use
the right one with higher level languages.

I think your problem is that you are thinking
logicaly and the Stamp basic is working
bitwise.

Note.... the bitwise type of operator should
not be confused with operations on a specific
bit in a byte like the pic can preform.

Bitwise means that every bit in the byte or
variable is operated on.  And this may be what
the Stamp basic uses.  So the following applies
to the operator functioning in a bitwise manner.

False means that all bits in the byte or variable
are off.  True means that all bits in byte or
variable are not off. (at least one bit in the
byte or variable is on)

The NOT operator complements the byte (or variable).
So that every bit that was on before the NOT is
off after the NOT.  And every bit that was off before
the NOT, is on after the NOT.

I keep saying byte or variable because in some
languages a integer is two bytes long.  And
I don't know how many butes the Stamp uses
for a variable.

If you NOT 0 then the results will be all
bits on, or the value -1.  And if you NOT
the value -1 then the results will be all
bits off, or 0.  This is why it is best to
use -1 as the TRUE value when setting flags.
It is not necessary, but when you start
NOT'ing them, they will work properly.
<properly if you are thinking logicaly>

With any value other than 0 or -1, the NOT will
just toggle all the bits and some will toggle
on and the rest will toggle off.  But in the
end, the result will allways have one or more
bits on and be considered TRUE.

If you NOT the value of 1, then all bits are
on except the Least Signifuenct Bit 'LSB".
And this will show as a value of -2.

Now a question.

What does 1 AND 2 return?
And how about 1 OR 2?

Have fun,

Bill C.    bill@cornutt.com


----------
> Hello
>
> According to the stamp manual page 274, if I understand it you can write an
> If...then statement like:
>
> Flag     var    byte
> Flag  =  1
>
> If flag then  istrue          'Value is true- True is any value other than 0
>      and
> If NOT flag then istrue    'Is also true
>
> Isn't NOT 1 the same as 0 or 2...any non 0 number. If true is any value other
> than 0 and "NOT 1 is true" as well as any non-zero numberI don't understand
> the difference.
>
> For example whats the difference between these two commands
>
> IF NOT in1 then si2c_rbyte_dl
>     and
> IF bit_count then si2c_rbyte_lp
>
>
> Thanks
>
> Jon
>