[Tzfat]

Is there some prohibition against this in avionics? Many automobiles use "analog" displays driven by computer signals. All the sensors - vehicle speed, coolant temp, oil pressure, etc. - report to the computer, which in turn sends output to the instrument panel. There are even analog speedometers that connect only to power, ground and a gps antenna.

No, the primary altimeters are not dials. There are two Primary Flight Displays (PFD), which are digital screens. The altitude is displayed as a digital readout, as well as an altitude "tape." There is a backup digital screen with digital readout for altitude.

[onedoug]

Those backups look analogue to me. Am I wrong?