I had two of the excellent Sony HDD 250 DVRs. They are/were better than Tivo until this last generation....well built, and a good first effort.
They got data from TV Guide onscreen. Listings, info, and time.
TV Guide onscreen was a listing service that would download from an OTA or cable station, interlaced into the signal. It was carried by PBS in the analog era, then CBS when digital transition took place.
TV Guide was sold to Rovi (Macrovision). Shortly thereafter, the listing service was shut down. Sony and Rovi were both mute as to those of us who had bought into TV Guide onscreen. I mean, really, who could get screwed by TV GUIDE ????
So much for the old economy and assumptions.
We were left high and dry. There was no alternate way to get the listings. Some units with later versions of TV Guide onscreen were internet compatible, but these weren't.
Now, I'm not ranting about free listings. These units would not take a time stamp from anything other than a TVGOS source, over the air... So, once the TVGOS service died, your clock did too. No, there was no "clock set" in the menu. Whose idea or requirement this was should be shot. Twice.
Some convoluted work arounds were devised, but the simple fact is that you had a random clock when you plugged it in. For the normal person, you just bricked it. No TVGOS signal = no clock = no programming.
Thanks Sony.