[Dave Moll]

I will have to check whether my (Sanyo) Betamax machine probably uses mains synch for its clock. I know my old VHS machine and (pre-digital DVD recorder) used the TDSP (Television Data Service Packet?) broadcast alongside Teletext - and promptly ceased to keep correct time once analogue televsion was switched off.

I replaced both of these with a (Daewoo) combined VHS/DVD recorder that somehow manages to keep correct time, even though it doesn't it doesn't have a DTV tuner.