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4.3 cell

A cell is a picture pattern of horizontal 8 dots x vertical 8 dots, which is stored in VRAM. The number of character colors (number of colors per cell) can be selected from among 16 colors, 256 colors, 2048 colors, 32768 colors, and 16.77 million colors (16,777,216 colors). Depending on the number of colors, the size of each dot color data and the VRAM capacity required for one cell of data change.

■ Character Colors

There are two color formats for displaying characters: the palette format and the RGB format. The palette format uses the color RAM address data specified by the palette number in the pattern name data and the dot color code in the cell data as the display color data. RGB format uses cell data as display color data. Table 4.1 shows the number of character colors and the number of bits per dot for each color format.

Table 4.1 Number of character colors and dot data size 
 Color format 
 Number of character colors 
 bits per dot 
 Palette format 
 16 colors 
 4 bits 
 256 colors 
 8 bits 
 2048 colors 
 16 bits (only the lower 11 bits are used) 
 RGB format 
 32768 colors 
 16 bits 
 16.77 million colors 
 32 bits (only MSB and lower 24 bits are used)
[Note] In color RAM mode 0 and 2, 2048 colors becomes 1024 colors.

■ Cell data structure

The data structure of each cell stored in the character pattern table varies depending on the number of bits per dot. The boundary when storing to VRAM is 20H regardless of the number of bits per dot.
∙ Cell data configuration is shown in Table 4.2 and Figure 4.5.

Table 4.2 Cell Data Structure 
 bits per dot 
 cell data  
 boundary 
 4 bits / dot 
 32 bytes / cell 
 20H Byte 
 8 bits / dot 
 64 bytes / cell 
 20H Byte 
 16 bits / dot 
 128 bytes / cell 
 20H Byte 
 32 bits / dot 
 256 bytes / cell 
 20H Byte

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