The math.bits vocabulary implements words that represent a positive integer as a virtual sequence of bits in order of ascending significance, e.g. { f f f t } is 8.

bits

<bits> ( number length -- bits )

make-bits ( number -- bits )

bits>number ( seq -- number )

If you need binary digits instead of boolean, then you can use these:

binary-bits

<binary-bits> ( number length -- binary-bits )

make-binary-bits ( number -- binary-bits )