■1.2 Screen mode

●Screen mode and display range

• The screen modes and the coordinate values displayed at that time are as follows.

  Table 1.2 Screen mode and display range

  screen mode	X range		Y range
  	standard	At high resolution
  non-interlaced Single dense interlace NTSC, PAL Width 320 x height 224 pixels Width 320 x height 240 pixels Width 352 x height 224 pixels Width 352 x height 240 pixels	0≦X≦319 0≦X≦319 0≦X≦351 0≦X≦351	0≦X≦639 0≦X≦639 0≦X≦703 0≦X≦703	0≦Y≦223 0≦Y≦239 0≦Y≦223 0≦Y≦239
  double dense interlace NTSC, PAL Width 320 x height 224 pixels Width 320 x height 240 pixels Width 352 x height 224 pixels Width 352 x height 240 pixels	0≦X≦319 0≦X≦319 0≦X≦351 0≦X≦351	0≦X≦639 0≦X≦639 0≦X≦703 0≦X≦703	0≦Y≦447 0≦Y≦479 0≦Y≦447 0≦Y≦479
  non-interlaced 31kHz, HDTV Width 320 x height 240 pixels Width 352 x height 240 pixels	0≦X≦319 0≦X≦351		0≦Y≦239 0≦Y≦239

  However, this is the range of coordinates, not the size that occupies the frame buffer. For the size of the frame buffer, see " Frame Buffer ( 2.1 Address Map ) ".

• In the case of high-resolution, it will be 8 bits/pixel, which is half of the standard time. At this time, rotating display of the frame buffer is not possible.

• Frame buffer rotation cannot be displayed during double-dense interlacing.

• For interlacing, when switching frame buffers for each field (double-dense interlacing), both frame buffers become one frame.

• When switching frame buffers every two fields (single dense interlacing), the same picture is displayed in even and odd fields. In both cases, there will be no gaps between the scan lines.

• When using simple interlacing, the resolution is the same as when using non-interlacing, and the method of writing to the frame buffer is also the same.

• On a 31kHz HDTV, the same color is displayed in units of 4 pixels, 2 pixels each vertically and horizontally. In other words, the resolution is the same as the standard 320 x 240 (31kHz) or 352 x 240 (HDTV), and the method of writing to the frame buffer is also the same.

• For details on how to set up interlace, please refer to the VDP2 User's Manual .

●Frame buffer rotation readout

• By reading the frame buffer diagonally, the entire frame buffer plane can be rotated and displayed.
  

• The part whose display coordinates exceed the frame buffer address range is treated as transparent (XX00H for 8bit/pixel, 0000H for 16bit/pixel).

• Even if the frame buffer is rotated and read, the clipping area and erase write area are fixed relative to the frame buffer plane. Therefore, the clipping area and erase write area will be tilted with respect to the display screen.

• In order to prevent the display screen from being cut off even when the frame buffer is rotated, the coordinate range of the frame buffer must be large. In this case, the frame buffer is set to 8bit/pixel, and the screen is set to 512x512 instead of 512x256. The number of colors that can be produced simultaneously is within 256.

• Rotation is prohibited when set to normal, high resolution, HDTV, and double density interlace.

• The read start coordinate and read movement value for frame buffer rotation read are received from VDP2.

• Frame buffer rotation reading is valid only at rotation 16 and rotation 8. Anything else is prohibited. Even if rotation data is sent from VDP2 during non-rotation, it is invalid and the parameters of VDP1 are valid.