■ 4.1 TV mode selection register

• When VBE = 1, erase light is performed during V blank. VBE = 1 can be set only when FCM = 1 and FCT = 1 are written. For details, refer to " 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 the setting at the same time.

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

• Specifies the TV display mode.

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

• When TVM = 10B (2), the frame buffer is only 512 horizontal x 256 vertical pixels, so if you tilt the screen a lot, a transparent area will appear on the display screen.

• When HDTV is specified (TVM = 100B (4)), only non-interlace can be set, and when rotation display is specified (TVM = 10B (2), 011B (3)), only non-interlace and single-dense interlace can be set. Disable double-dense interlacing (DIE bit = 0) in the frame buffer switching mode register. For details, refer to " 4.2 Frame Buffer Switching Mode Register ".

• Set the 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 function of each bit is as follows, but since there are restrictions on the combination of bits, strictly observe the settings in Table 4.2.
  Bit 2: HDTV valid bit
  0 = NTSC, PAL
  1 = HDTV, 31kHz

  Bit 1: Framebuffer Rotation valid bit
  0 = non-rotating
  1 = rotation

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

  Table 4.2 Screen mode

  TVM			Screen mode		Bit width	Framebuffer screen size	Interlace	VDP CLK (MHz)
  bit2	bit1	bit0	name	resolution				At NTSC	At PAL
  0	0	0	Normal (NTSC, PAL)	320 x 224 320 x 240 352 x 224 352 x 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 x 224 640 x 240 704 x 224 704 x 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 x 224 320 x 240 352 x 224 352 x 240	16bit / pixel	Horizontal 512 × Vertical 256	Only single density is 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 x 224 320 x 240 352 x 224 352 x 240	8bit / pixel	Horizontal 512 × Vertical 512	Only single density is possible	26.8426 26.8426 28.6364 28.6364	26.6564 26.6564 28.4375 28.4375
  1	0	0	HDTV (31kHz, HDTV)	320 x 240 352 x 240	16bit / pixel	Horizontal 512 x Vertical 256	Ban	26.8426 28.6364	26.6564 28.4375

  Strict adherence ★ Settings other than the above are prohibited (please do not set)