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C H A P T E R 2
Getting Started
Effects of System Resets on Application Data
Effects of System Resets on Application Data
Two kinds of reset operations--hard resets and soft resets--can occur on Newton
devices. All data in working RAM (the NewtonScript heap and the operating
system domain) is erased when a hard or soft reset occurs.
Unless a hard reset occurs, soups remain in RAM until they are removed explicitly,
even if the Newton device is powered down. Soups are not affected by soft resets,
as they are stored in the protected storage domain. The remainder of this section
describes reset operations in more detail and suggests ways to ensure that your
application can deal with resets appropriately.
A hard reset occurs at least once in the life of any Newton device--when it is
initially powered on. The hard reset returns all internal RAM to a known state: all
soups are erased, all caches are purged, all application packages are erased from
the internal store, application RAM is reinitialized, the NewtonScript heap is
reinitialized, and the operating system restarts itself. It's the end (or beginning) of
the world as your application knows it.
Data on external stores is not affected by a hard reset.
A hard reset is initiated only in hardware by the user. Extreme precautions have
been taken to ensure that this action is deliberate. On the MessagePad, the user
must simultaneously manipulate the power and reset switches to initiate the
hardware reset. After this is accomplished, the hardware reset displays two dialog
boxes warning the user that all data is about to be erased; the user must confirm
this action in both dialog boxes before the hard reset takes place.
It is extremely unlikely that misbehaving application software would cause a hard
reset. However, a state similar to hardware reset may be achieved if the battery that
backs up internal RAM is removed or fails completely.
It's advisable to test your application's ability to install itself and run on a system
that has been initialized with a hard reset. The exact sequence of steps required to
hard reset a Newton device is documented in its user guide.
Newton devices may also perform a soft reset operation. A soft reset erases all data
stored by applications in the NewtonScript heap, for example all data stored in
slots in views or other frames in memory. A soft reset also reinitializes the data
storage system frames cache, while leaving soup data intact. Any frames in the
cache are lost, such as new or modified entries that have not been written back to
the soup. A soft reset can be initiated in software by the operating system or from
hardware by the user.
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