This is GNU bc 1.04.

The full distribution of GNU bc-1.04 may be found at any GNU software
archive.  The master copy is at ftp://prep.ai.mit.edu/pub/gnu/bc-1.04.tar.gz.

Not everything included in the full bc-1.04 distribution is included.
The files included here are only the needed files for building bc on
NetBSD.  Their location in the NetBSD tree are different than in the
original bc-1.04 source tree.