■4.1 TV mode selection register

• When VBE=1, erase write is performed during V blank. VBE=1 can be set only when FCM=1 and FCT=1 are written. For more information, see 4.2 Frame Buffer Switching Mode Register .

• When setting the VBE value to 0 or 1, be sure to set the TVM with the same value as before setting at the same time.

• Set VBE immediately after the V blank IN interrupt. Access is prohibited from the first H blank IN interrupt after the V blank IN interrupt until the next H blank IN interrupt.

• Specify the TV display mode.

• Please refer to " Screen mode and display range " for the coordinate values of the displayed area.

• When TVM=010B(2), the frame buffer is only 512 pixels wide x 256 pixels high, so if you tilt the screen too much, a transparent area will appear on the display screen.

• When specifying HDTV (TVM=100B(4)), only non-interlace can be set, and when specifying rotated display (TVM=010B(2), 011B(3)), only non-interlace and single density interlace can be set. Disable double-dense interlacing (DIE bit = 0) using the frame buffer switching mode register. For details, see " 4.2 Frame Buffer Switching Mode Register ".

• Set TVM between the second H blank IN interrupt after the V blank IN interrupt and the H blank IN interrupt immediately after the V blank OUT interrupt.

• The functions of each bit are as follows, but there are restrictions on the combinations of bits, so please strictly adhere to the setting values in Table 4.2.
  Bit 2: HDTV enable bit
  0=NTSC, PAL
  1=HDTV, 31kHz

  Bit 1: Frame buffer rotation enable bit
  0=no rotation
  1=rotation

  Bit 0: Bit width selection bit
  0=16bit/pixel
  1=8bit/pixel

  Table 4.2 Screen mode

  TVM			screen mode		bit width	frame buffer Screen size	Inter race	VDP CLK (MHz)
  bit2	bit1	bit0	name	resolution				NTSC time	When PAL
  0	0	0	normal (NTSC, PAL)	320×224 320×240 352×224 352×240	16bit/pixel	Horizontal 512 × Vertical 256	Possible	26.8426 26.8426 28.6364 28.6364	26.6564 26.6564 28.4375 28.4375
  0	0	1	high resolution (NTSC, PAL high resolution)	640×224 640×240 704×224 704×240	8bit/pixel	Horizontal 1024 × Vertical 256	Possible	26.8426 26.8426 28.6364 28.6364	26.6564 26.6564 28.4375 28.4375
  0	1	0	rotation 16 (NTSC, PAL rotate)	320×224 320×240 352×224 352×240	16bit/pixel	Horizontal 512 × Vertical 256	Single density only Possible	26.8426 26.8426 28.6364 28.6364	26.6564 26.6564 28.4375 28.4375
  0	1	1	rotation 8 (NTSC, PAL rotate)	320×224 320×240 352×224 352×240	8bit/pixel	Horizontal 512 × Vertical 512	Single density only Possible	26.8426 26.8426 28.6364 28.6364	26.6564 26.6564 28.4375 28.4375
  1	0	0	HDTV (31kHz, HDTV)	320×240 352×240	16bit/pixel	Width 512× Vertical 256	Ban	26.8426 28.6364	26.6564 28.4375

  Strictly observed★Settings other than those listed above are prohibited (please do not set them)