MCNP is a very typical old-school Fortran code. It takes practice to get a feel for reading that stuff, but it has its own beauty once you get the hang of it.

MCNP is a very typical old-school Fortran code. It takes practice to get a feel for reading that stuff, but it has its own beauty once you get the hang of it. SCALE is mid-way into migrating to C++. AFAIK though MCNP isn't going to change.