Every combination possible 0 and 1 on 9 digits

I have 9 letters and they can be 0 or 1, I am looking for a way to find all possible combinations on those 9 digits letters.
ex:
a1
b0
c0
d0
e0
f0
g0
h0
i0

then

a1
b1
c0
d0
e0
f0
g0
h0
i0

Until got all possibilities.

Originally Posted by feejo

I have 9 letters and they can be 0 or 1, I am looking for a way to find all possible combinations on those 9 digits letters.
ex:
a1
b0
c0
d0
e0
f0
g0
h0
i0

then

a1
b1
c0
d0
e0
f0
g0
h0
i0

Until got all possibilities.

I do not see a conection in your example...

ex:
you have 3 colors you can choose from
yellow, green, red.
I can do
y-g-r-
y-r-g-
g-y-r
g-r-y

etc...

DO you understand now what I mean?