How much data can I see on the screen at one time?
The TV2 ThermaViewer will store a bit more than 80,000 measurements for each sensor if you are logging temperature only. If you are logging temperature and humidity the TV2 will store 60,000 pairs of temperature and humidity readings.
How much time does 80,000 measurements cover?
If you are storing data once every 10 minutes, 80,000 data points is more than 1.5 years of samples. You can see either part or all of this data on the screen. How much time your see depends on whether you are zoomed out or not. If you are zoomed out to 'zoom=10' you will see all of the measurements ( more than a year and a half of temperature history) on the LCD at one time without paging back and forth.
It might be hard to figure out what you are actually seeing, however, with that much data on the screen at once, but you can zoom in until you are looking at as little or as much data as you can interpret.
A more in-depth description of how the zoom in and out function works can be found in the appendix of the users guide.