Change Note hwos Firmware 3.09.4
================================

- When diving in CCR or pSCR mode: An attention and a warning for the gas
  density has been added. The attention will be given when the density
  of the current gas mixture reaches 6.0 grams per liter. Upon reaching
  6.5 grams per liter, a warning will be given. The checks can be enabled
  or disabled via the menu CCR/pSCR setup > more.

- Incremented upper limit for SAC Work to 80 l/min to ease usage of the
  OSTC gas needs calculation in Rock-Bottom mode.

- Faster response to button events while in dive mode.

- Hardened all USB/Bluetooth communication against data losses and timeouts.

- Fixed Bluetooth item disappearing from menu.

- A new Firmware Recovery Feature has been added: the currently active firmware
  can be backed-up and restored later on while other firmwares have been loaded
  thereafter. The feature is accessible via Settings -> System Settings ->
  Reset Menu -> Reboot and becomes available with the first firmware load after
  the V3.09 beta 4 (or later) is already on the unit.


Change Note hwos Firmware 3.09.2 + 3.09.3
=========================================

- Added a function to acknowledge pending alarms, attentions and advices
  so that the exclamation-mark sign disappears: after pressing the left
  button until "Ackn?" appears, a press on the right button acknowledges
  the current alarm, attention or advice and suppresses the related sign.

- Bugfixes: NDL not shown in big layout, external sensor not selectable,
  flash-write operation on some OSTC hardware, graphical garbage in depth
  output in big layout when deeper than 100 m.


Change Note hwos Firmware 3.09.1
================================

- Removed option 'ascent speed', ascent calculation is done with a fixed
  speed of 10 meters/minute now (equals the ascent speed limit by Bühlmann).

- Improved calculation accuracy of the initial ascent. Remark: this will
  have a slight impact on the resulting deco schedule compared to firmware
  3.07.

- The deco calculator now figures in the salinity setting.

- Aligned logbook and last dive summery of avg and max depth regarding
  rounding and incorporation of salinity setting.

- Done some fine-tuning of depth outputs when using imperial units (feet).

- In dive mode, sometimes the temperature was not shown any more after a
  gas change - fixed now.

- The menu system around setting up the dive mode & settings has been
  decluttered. All settings are now sorted into the groups dive setup,
  deco setup, SAC (gas needs) setup, ppO2 setup and stops & depths setup.

- There is a new option "Swap on empty" in Dive Setup -> SAC Setup.
  It is only effective if "CalcGas(B/O)" is switched on, too. If both
  options are switched on, the deco calculation will switch to another
  tank (i.e. gas) once the tank of the current gas is calculated to be
  used up.
  This function can be used to automatically calculate a contingency in
  case of running out of a deco gas, as the deco calculation will then
  continue to calculate a deco making use of the spares from the another
  gases carried. Another application is with two or more tanks holding
  the same gas (i.e. independent double configuration, side-mount), as
  the calculations will then take the cumulative amount of gas carried
  into account before raising a gas needs attention or alarm.

- Fixed the urge of the better gas hint to always favor one specific gas
  out of a set of two or more gases that have the same change depth.

- For dives done on firmware >= 3.09 the logbook will have one more page
  showing the tissue pressures and supersaturation levels as of at the
  end of dive (i.e. when surfacing).

- As long as a gas or diluent is currently selected as breathed, it can
  not be set into the lost state any more.

- When changing the battery or doing a cold start, the current CNS value
  does not get lost any more.

- During loading of a new firmware the clock will not loose time any more
  (on old firmware it became late by about 15 sec on each firmware update).

- When run from a 3.6 V battery (either replaceable or built-in), the
  surface mode timeout is now extended to 4 minutes before going to sleep
  mode. If the OSTC is run from 1.5 V disposables, the timeout remains at
  the previous 90 seconds to save on battery runtime.

- Internal improvement: the code for the internal storage system and for
  the communication system (firmware uploading, dive data downloading)
  has been re-factored to secure maintainability for the next years to come.

- Internal improvement: the scheduler for the dive mode calculation plans
  (fTTS, bailout) has been completely rewritten for better maintainability.