If a time machine does allow for changing history, it's easy to imagine how to compute it; you could easily write a computer program which would simulate that universe and its time travel, given sufficient computing power. You would store the state of the universe in RAM and simulate it under the programmed 'laws of physics'. Every nanosecond, say, you'd save a copy of the universe's state to disk. When the Time-Changer was activated at 9pm, you'd retrieve the saved state of the universe from one hour ago at 8pm, load it into RAM, and then insert the Time-Changer and its user in the appropriate place. This would, of course, dump the rest of the universe from 9pm into oblivion - no processing would continue onward from that point, which is the same as ending that world and killing everyone in it.

Is there a word for time travel that works like this? I'm writing a novel that has it, and would like to be able to succinctly describe it to people who ask what it's about or how the time travel works.

(I'm not invoking computer simulation, but the effects as far as the characters see are like this - or rather, the characters see time travelers from the future but never get to see the versions of the universe where they get to remember seeing someone leave to travel to the past.)