Originally Posted by L David Matheny
If you're asking what I think you're asking, I'm pretty sure it never worked that way. The Live TV button switches tuners, and the Enter button swaps to the last channel on the current tuner (without switching). Changing channels (with the Enter button or any other way) will dump the live buffer on that tuner. If you want to keep two live buffers going, you have to switch tuners without changing the channel on either tuner. You pause before switching so you don't lose your place in the buffer, and if a recording starts then the orphaned buffer ahead of it will disappear when you get to the end (where the recording started). I don't watch much live TV, but I'm sure somebody will correct me if I've garbled this somehow.
Not quite on the Enter button.
The Enter button changes to the previous channel. That's usually but not always on the same tuner. However Sometimes
Enter will swap tuners rather than dumping the buffer and changing the channel on the same tuner. This usually happens because you were using the channel up/down buttons and went past the channel the other tuner was on. TiVo tries
to keep the tuners on different channels; and this can make the scenario surprisingly complicated.
Say tuner 1 is on channel 5, and tuner 2 is on channel 4. Switch to tuner 2 and press channel up. Instead of having both tuners on channel 5 the TiVo will automatically swap tuners. You'll be watching channel 5, but suddenly be on tuner 1. At this point if you press Enter the TiVo will again avoid having two tuners on the same channel by swapping tuners. (The channel each tuner is on didn't change in this scenario; just which tuner you were watching)
But if you'd pressed channel up again you'd have tuner 1 on channel 6 (having dumped its buffer) and tuner 2 still on channel 4. Pressing enter at that point would cause tuner 1 change back to channel 5 (dumping its buffer again).
Note: Previous paragraph assumes channel 5 isn't actively being recorded while you're doing this. If it was recording then the behavior is slightly different. Tuner 1 = Chan 5; Tuner 2 = Chan 4; from chan 4 press chan up. You're now watching Tuner 1 on Chan 5 (so no chance so far). But press up again and TiVo can't dump the Chan 5 buffer because its part of a recording, so it changes Tuner 2 to channel 6 and switches you back to watching tuner 2.
LiveTV always swaps tuners, it will never dump the buffer of any tuner. (Nitpick; if the TiVo gets into remote backwards compatibility mode LiveTV will actually bring up the guide instead of changing tuners. But it still won't dump any buffers)