F is for… FM Synthesis
Towards the end of the ‘80s, sound chips were becoming more advanced, and many were based around FM synthesis, giving game composers the power to inflict parping synth brass, bell-like tones and funny wobbling noises upon their listeners.
Games consoles like the Sega Mega Drive/Genesis used such chips, as did early PC Ad Lib cards. However, the growing sophistication of these chips (increased numbers of channels and better sounds) and their ability to play back samples meant that they didn't have so much in common with earlier chip music.
F is also for... Fake-bit
That is, music that sounds like chip music but is made with modern equipment rather than authentic vintage hardware.