What is the difference between firmware v3.4 and v4.2?

- Version 4.2 adds some minor changes to support the MOD4-B revision of the hardware.
  You probably have a MOD4-A hardware revision.
  It is printed on the board to the right of the display.

Is it possible to set the Zlog to not restart another fulll sample period when it's still
above "start-sampling-height"?

-The current firmware will not do that.
 It will restart the recording when it see the condition for start.

When I select the Zlog to stop after say 60s via my PC interface,
it will always stop after twice the selected time.

- Ok, I will have to check on that.

2007-08-01:

- I will get a new software update on the download site in a few days.
  In the meantime, the workaround is to put in half the desired time.
  Thanks for pointing this out.

How accurate is the Zlog altimeter?

- There will be variations due to environmental atmospheric pressure highs and
  lows, but this would only affect absolute altitude readings. Assuming the
  altimeters were zeroed at the start of the flight, that should not be a factor.
  ZLog has been verified with GPS, calibrated pressure chamber, and full-size aircraft altimeters

------------------