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Page 14 Epson Research and Development
Vancouver Design Center
S1D13705 Windows® CE 3.x Display Drivers
X27A-E-006-01 Issue Date: 01/05/25
• Since display data is not saved and not repainted, this is the FASTEST mode.
• Main display data in display memory must NOT be corrupted or lost on sus-
pend. The memory clock must remain running.
• Off-screen data in display memory must NOT be corrupted or lost on sus-
pend. The memory clock must remain running.
• This mode cannot be used if power to the display memory is turned off.
b. PORepaint=1
• This is the default mode for Windows CE.
• This mode tells Windows CE to save the main display data to the system
memory on suspend.
• This mode is used if display memory power is going to be turned off when the
system is suspended, and there is enough system memory to save the image.
• Any off-screen data in display memory is LOST when suspended. Therefore
off-screen memory usage must either be disabled in the display driver (i.e:
EnablePreferVmem not defined in SOURCES file), or new OEM-specific
code must be added to the display driver to save off-screen data to system
memory when the system is suspended, and restored when resumed.
• If off-screen data is used (provided that the OEM has provided code to save
off-screen data when the system suspends), additional code must be added to
the display driver’s surface allocation routine to prevent the display driver
from allocating the “main memory save region” in display memory. When
WinCE OS attempts to allocate a buffer to save the main display data, WinCE
OS marks the allocation request as preferring display memory. We believe
this is incorrect. Code must be added to prevent this specific allocation from
being allocated in display memory - it MUST be allocated from system mem-
ory.
• Since the main display data is copied to system memory on suspend, and then
simply copied back on resume, this mode is FAST, but not as fast as mode 0.
c. PORepaint=2
• This mode tells WinCE to not save the main display data on suspend, and
causes WinCE to REPAINT the main display on resume.
• This mode is used if display memory power is going to be turned off when the
system is suspended, and there is not enough system memory to save the im-
age.
• Any off-screen data in display memory is LOST, and since there is insuffi-
cient system memory to save display data, off-screen memory usage MUST
be disabled.
• When the system is resumed, WinCE instructs all running applications to re-
paint themselves. This is the SLOWEST of the three modes.