Function generator frequency measurement ?
Maybe a LM2907 frequency to voltage IC feeding into a second DVM chip could suffice ?
I have seen PIC programs for a PIC16F84 to do frequency measurement, displaying on an LCD - this could be ported to a PIC with analogue to digital converter onboard then it could do voltage measurement as well ???
Either way --- consider voltage measurement ... do you want peak voltage, average (as on cheaper multimeters, fine for pure sinewaves) or true RMS? all three methods give different answers on a triangular or sawtooth waveform !
My sig. genny (based on the same chip) just has a rough scale on the ampluitude control knob, I let my multimeter do anything I need accuracy for.