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Color RAM definition
- Defines color data for palletized sprites and scroll screens. The color data stored in the color RAM is in RGB format and has three modes. The mode is selected by the color RAM mode (CRMD1, CRMD0, bits 13, 12) of the RAM control register (18000EH).
The most significant bit of color data stored in the color RAM is an enable bit when the special color calculation mode is mode 3. When the special color operation mode is mode 3, the color format is palette format, and the color operation enable bit is 1, color operation is performed in dot units for dots that use color data with the most significant bit set to 1. The
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● Color RAM reference
- Color RAM is referenced from data of character pattern, bitmap pattern, and line color screen table. The color RAM address is represented by 11 bits. If the number of character colors or bitmap colors is 16, the upper 7-bit palette number is added to 11 bits, and if it is 256 colors, the upper 3-bit palette number is added to 11 bits. The The palette number of the character pattern is in the pattern name data and the auxiliary data of the pattern name control register, and the palette number of the bitmap pattern is in the bitmap palette number register.
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● Register
As a general rule, the - register is a 16-bit write-only register that specifies the VDP2 function. Some functions may span several registers, and some functions may be grouped into one register.
Set the register corresponding to the function to be used if necessary.
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