Reverse Amortization Calculator, Does it Exist?

[Casey Mericle]

Has anyone stumbled upon a "Reverse Amortization Calculator" or does anyone have an excel template of this.

To be clear I'm looking for a tool in which the principal is paid 1st & the interest is paid 2nd (the opposite of a traditional loan).  I'm not looking for a reverse mortgage calculator or a negative amortization calculator (at least I don't think that's the case).

Thanks in advance BP