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The Windows XP Embedded CF card, which is provided for Pro-face panel computers, is equipped with the EWF (Write Filter) function.
■ What is EWF?
■ What is this function for?
■ EWF Function Description
■ Detailed information
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| ■ What is EWF? |
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EWF is a function which protects a CF card from writing. Enabling this function prevents data writing to a CF card.
When EWF is enabled: Data cannot be written to a CF card
When EWF is disabled: Data can be written to a CF card |
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| ■ What is this function for? |
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If the EWF function is enabled, the data in a CF card is protected from erroneous writing including operational errors, unintended update, or deletion. Also this function prevents the lifetime being reduced by the number of writings to a CF card.
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Windows XP Embedded needs to be restarted after you change the settings of disabling/enabling the Write Filter. |
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The EWF settings cannot be applied to external drives other than the Windows XP Embedded CF card, such as
a USB flash drive or a CF card for data writing via
a PCMCIA connector. |
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Turning off the power when writing to a CF card may result in damaged or lost data. The Write Filter must be enabled. |
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Turning off the power when starting Windows XP Embedded may damage or lose the EWF settings information. |
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| ■ EWF Function Description |
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Even when the EWF function is enabled, information is updated as well as in the general hard disk environment. But why can information be updated even if the write protection is active? The followings explain data actions when the EWF function is enabled and data is updated.
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When the write filter is enabled
The access to a CF card is as shown below:
- Read: Direct access to a CF card
- Write: Access to the memory |
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When the write filter is disabled
The access to a CF card is as shown below:
- Read: Direct access to a CF card
- Write: Direct access to a CF card |
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| ■ Detailed information |
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For the detailed information, refer to the Windows XP Embedded reference manual.
Windows® XP Embedded 2G (NTFS) Reference Manual |
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