For a different perspective, and Arduino (Uno) has 32kb of available RAM (minus a tiny bot used by the bootloader).
There's a tremendous amount of projects demonstrating amazing things that can be done with much less computing resources available than a BIOS. I have _very_ little doubt that bit-twiddled 12-20kHz audio communication could easily be implemented in under 10% of the 383kB that seems to be available. (Assuming the speaker and microphone are available as GPIO-like interfaces to the BIOS/CPU.)
Except that UEFI has "system libraries" (among others for IPv4/v6 networking) that can be used after an OpenProtocol call.
In the future, AMI might add some OpenGL interfaces, too (see http://www.uefi.org/sites/default/files/resources/8_-_UEFI_S...)
.... except, at the BIOS level, there aren't many "system libraries". It's basically bare metal.