BIOS forensics?

Not sure about "forensic" but Qtech Pro will give you a more detailed info about the BIOS than anything else I tried
http//www.uxd.com/qtpro.shtml
http//www.uxd.com/qtpro-screen.shtml

Give UXD a call they may help you with limited Demo of the software?

I'm looking for a utility to acquire the system BIOS and output it to a file.

Have you checked old threads for earlier discussions? Like this one http//www.forensicfocus.com/Forums/viewtopic/t=8884/ ?

You want Copernicus

http//www.mitre.org/capabilities/cybersecurity/overview/cybersecurity-blog/copernicus-question-your-assumptions-about

It dumps the BIOS from a bunch of systems, but requires Windows 7 32/64 bit.

JB