Chapter 1 VDP2 functions

VDP2 has scrolling and priority functions. The scroll function is a function that defines a scroll screen and moves the screen vertically, horizontally, or rotationally. The priority function is a function that determines the display priority of multiple scroll screens, sprites, and external screens, and performs image processing such as color calculations and color offsets.

■1.1 System configuration

VDP2 has 4M or 8M bits of VRAM attached and 32K bits of color RAM. Image data is defined from the CPU through the SCU to VRAM and color RAM. Information that controls image display is also set in each register in the same way.
The data defined in VRAM is read out according to the register settings and becomes the image data for each scroll screen. The image data of each scroll screen, the sprite image data sent from VDP1, and the external image data sent from the outside are prioritized for display according to register settings and become display image data. When the display image data is in palette format, the color data defined in the color RAM is read out according to the value and converted into display color data. When the display image data is in RGB format, the display image data is converted into display color data as is. The display color data obtained in this way is output to a display device.
Figure 1.1 shows the VDP2 system configuration.

Figure 1.1 System configuration