Palm Database Programming The Electronic Version
Chapter 2: What You Need To Know About Palm Devices
This material was published in 1999. See the free
Palm OS Programming
online course I developed for
CodeWarriorU for some updated material.
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Resetting the Device
At some point, an application you're developing is going to corrupt
memory and crash or else freeze the device. Pressing the power button
is unlikely to help, since all it does is switch from one running mode
to another. At times like these you'll need to manually reset your
device.
There are three kinds of reset, and you should learn how to do each
one. But before you experiment, be sure to do a HotSync to backup your
device's current configuration. In fact, if you don't have a dedicated
testing device, regular HotSyncs will ensure that you don't lose any
data if you're forced to perform a hard reset as described in the
following section.
Soft Resets
The gentlest and most basic form of reset is known as the soft
reset. A soft reset clears the contents of the dynamic heap and
resets the operating system. The storage heaps, and hence all
applications and their data, are left untouched. All applications are
notified that the system has been reset, the details of which are
discussed in Chapter 4.
You perform a soft reset by using the tip of a straightened paper
clip to press gently into the Reset hole on the back of your device.
On the newer Palm III models, the unscrewed top of the stylus can
serve in place of a paper clip.
Modified Soft Resets
A step up from the soft reset is the modified soft reset. A
modified soft reset also clears the contents of the dynamic heap and
resets the operating system, but applications are not notified that a
reset has occurred. This allows you to get the device up and running
again if an application crashes while processing the notification sent
by a soft reset. System patches, which are primarily bug fixes to the
operating system, are also not loaded, in case they are the cause of a
crash.
You perform a modified soft reset by first pressing and holding
down the scroll up button and then performing a soft reset with a
paper clip.
If the system crashes immediately after a soft reset, try the
modified soft reset to avoid the crash.
Hard Resets
The final form of reset is the hard reset. A hard reset
erases the contents of the dynamic heap and all the storage heaps and
then resets the operating system. Any applications you've installed
and all their data are lost — the device is in the state
it was when you first took it out of its box. Regular backups will
allow you to recover your data after performing a hard reset.
You perform a hard reset by pressing and holding down the power
button, pushing the paper clip into the Reset hole, removing the paper
clip, and then releasing the power button. You will be asked to
confirm the hard reset by pressing the scroll up button. The device
then wipes itself clean.
A hard reset is hardly ever necessary. You're more likely to use it
to purposely wipe a device clean than to recover from a crash. One
time in which you'll need to do it is to change the user name of the
device. Assuming you've defined two or more user names using the Palm
Desktop software, the first HotSync after a hard reset lets you choose
which user name the device will use. If you only have a single device,
this is useful for impersonating different users in order to fully
test an application. Be sure to do a complete backup before doing the
hard reset and resetting the user name. When you're done testing, do
another hard reset, use the HotSync Manager to make the desktop files
overwrite the handheld files, and then perform a HotSync, choosing the
original user name for the device. Your device will be restored to its
previous state.
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Copyright ©1999 by Eric Giguere. All rights reserved.
From Palm Database Programming: The Complete Developer's Guide.
Reprinted here with permission from the publisher. Please see the
copyright
and disclaimer notices for more details.
If you find the material useful, consider buying one of
my books,
linking to this site from your own site or in your weblog,
or sending me a note.
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