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HARDWARE ManualVDP2 User's ManualChapter 2 TV Screen
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VDP2 User's Manual/Chapter 2 TV Screen

■2.2 Interlace mode

VDP2's interlace mode (screen scanning method) includes non-interlace, single-density interlace, and double-density interlace. In non-interlace mode, one frame is one field (1/60 second). In simple interlace mode, one frame consists of two fields (1/30 seconds), but the same image is displayed in even and odd fields. In double-dense interlace mode, one frame consists of two fields (1/30 seconds), and separate images are displayed in the even and odd fields. Both single-dense interlaced mode and double-dense interlaced mode have no gaps between scan lines, but the actual vertical resolution of single-dense interlaced mode is the same as that of non-interlaced mode. It will be the same. Figure 2.1 shows how to display using interlace settings.

Figure 2.1 Display method using interlace settings
8x8 dot character pattern
●Non-interlace mode
Since the scan will be in the same location every field, there will be some locations that are not scanned.
One frame is one field (1/60 second).

●Single dense interlace mode
Scanning is performed in both odd and even fields, but the same picture is displayed, so the vertical resolution is the same as in non-interlace mode.
One frame consists of two fields (1/30 seconds).

●Double-dense interlace mode
Scanning is performed in both odd and even fields, and different pictures are displayed, so the vertical resolution is twice that of non-interlaced mode.
One frame consists of two fields (1/30 seconds).

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HARDWARE ManualVDP2 User's ManualChapter 2 TV Screen
Copyright SEGA ENTERPRISES, LTD., 1997