@kb9ens I don't know the internals of the power supply oscillators. It could be a quartz oscillator, but I wouldn't be surprised if it were just R-C, since the timing isn't particularly important.
As for the computer, it is synchronized to the disk, so its clock comes from a timing track on the disk rather than a quartz oscillator.
@kenshirriff Woah... sounds like that would also be resilient to transient currents and restoration of time after a transient induced shutdown. As ever clever clever...