Some programs need to determine if the Workbench screen is in PAL or NTSC mode. Before release 2.0, it was impossible for the system to switch between NTSC and PAL. The PAL/NTSC state in which the machine booted dictated the mode of its displays. Pre-V36 systems could determine the PAL/NTSC state of the machine by examining a bit the in GfxBase->DisplayFlags field, which is set at boot time under all versions of the OS. Thanks to the ECS and the new system software, PAL and NTSC display resolutions can coexist, which obsoletes examining GfxBase->DisplayFlags to determine the PAL/NTSC state of a particular system. Release 2.0 ignores the PAL/NTSC flag after it sets the flag at boot time. This means that under 2.0, if the system boots as NTSC, it is not possible to open a PAL screen in a way that will work correctly with release 1.3. To respect the user setup of the Workbench rather than the default video mode, a program should use the V36 graphics.library and intuition.library functions to determine the display mode ID of the Workbench screen. Using that ID, an application can open a screen or find more information about the properties of the Workbench screen. The extscreen.c example at the end of this article shows how to check for a PAL mode screen under any version of the operating system.
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