• The color bank is a bit added to the high-order bits when writing the pixel data of the character pattern to the frame buffer when the color mode of the texture part is the color bank mode.
• The color bank is specified by 16 bits, but the lower 4 bits should be fixed to 0. Depending on the color mode, it will be 12, 10, 9, 8bit. The addition is as follows.
• At 16bit / pixel, this data is written to the frame buffer as it is. When it is 8bit / pixel, the lower 8bit is written.

┌─────────────────────────────┐┐
Color bank │ Color bank 0 0 0 0 │ │ * 1
└─────────────┬───────┬───────┘┘
┌─────────────┴───────┼─┬─┬─┬─┐┐
16-color mode │ Color bank top 12 bits │ ○ │ ○ │ ○ │ ○ │ │ * 2
└─────────────┬───────┴─┴─┴─┴─┘│
┌─────────────┴───┬─┬─┬─┬─┬─┬─┐│
64 color mode │ Color bank top 10 bits │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ │
└─────────────┬───┴─┴─┴─┴─┴─┴─┘│
┌─────────────┴─┬─┬─┬─┬─┬─┬─┬─┐│
128 color mode │ color bank top 9 bits │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ │
└─────────────┬─┴─┴─┴─┴─┴─┴─┴─┘│
┌─────────────┼─┬─┬─┬─┬─┬─┬─┬─┐│
256 color mode │ color bank top 8 bits │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ │
└─────────────┼─┴─┴─┴─┴─┴─┴─┴─┘┘
└┬─────────────────────────────┘
↓ └┬──────────────┘
At 16 bit / pixel ↓
For 8bit / pixel ┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
RGB mode │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ * 2
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘

┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
Lookup │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │ ○ │
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘
[Supplement] In the lookup table mode, the lookup table data referenced from the defined character pattern is written to the frame buffer. [Note] * 1 : The lower 4 bits of the color bank are fixed to "0". * 2 : For ○ marks, the bit data of the defined character pattern is written to the frame buffer.

• The data written in the frame buffer is transferred to VDP2 as 16-bit data as it is when it becomes the display buffer in the next frame.
• The relationship between the color bank, definition character pattern data, and drawing frame buffer data is shown below.

• Defines the address of the color lookup table.
• When the color mode is the lookup table mode, the 4-bit data of the character pattern of the texture part is converted to 16-bit pixel data by referring to the color lookup table and written to the frame buffer.
• The color lookup table defines a 16-bit 16-color color code. Since the 16-bit data on the table is written to the frame buffer as it is, there is no distinction between color bank code and RGB code as the character pattern of texture parts.
  When read to VDP2, it is treated as a color bank code when the 16-bit MSB is 0, and as an RGB code when it is 1.
• The color look-up table address defines the address / 8H of the color look-up table. Since the color lookup table is defined by the boundary of 20HByte, the LSB2bit of the lookup table address is fixed to 00.

Specified by table address　
Character pattern 16 colors color look-up table frame buffer　
┏━━━━━━━━━━┓ ┏━━━━━━━━━━┓ ┏━━━━━━━━━━┓
┃ ┃ + 00H ┃ 16-bit data ┃ (0H color code) ┃ ┃
┃┃┠──────────┨┃┃
┃ ┃ + 02H ┃ 16-bit data ┃ (1H color code) ┃ ┃
┃┃┠──────────┨┃┃
┃ ┃ + 03H ┃ 16-bit data ┃ (2H color code) ┃ ┃
┃┃┠──────────┨┃┃
┃ ┃: ┃: ┃: ┃ ┃
┠──────────┨: ┃: ┃: ┠──────────┨
┃Definition 4-bit data ┃ →: ┃: ┃: → ┃Drawing 16-bit data ┃
┠──────────┨: ┃: ┃: ┠──────────┨
┃ ┃: ┃: ┃: ┃ ┃
┃┃┠──────────┨┃┃
┃ ┃ + 1CH ┃ 16-bit data ┃ (EH color code) ┃ ┃
┃┃┠──────────┨┃┃
┃ ┃ + 1EH ┃ 16-bit data ┃ (FH color code) ┃ ┃
┗━━━━━━━━━━┛ ┗━━━━━━━━━━┛ ┗━━━━━━━━━━┛
　
● The 16-bit data of the color lookup table selected with 4 bits of the character pattern remains as it is.　
It is written to the frame buffer as pixel data.　

• Non-textured color defines the color of non-textured parts.
• For non-texture parts, the non-texture color is written to the frame buffer as pixel data as it is.
• Non-texture colors are independent of transparent color codes and end codes.
• When the display mode is 8bit / pixel, the lower 8bit is valid. At this time, only the color bank code can be specified.
• When performing color calculation (excluding shadows) on non-textured parts, be sure to set the RGB code for the non-textured color.