■ DESCRIPTION
The MB90092 is the display controller for displaying text and graphics on the TV screen. The MB90092 incorporates display memory (VRAM), a font memory interface, and a video signal generator, allowing text and graphics to be displayed in conjunction with a small number of external components. The MB90092 can provide two screens, called the main screen and the sub-screen, either independently or overlayed one on top of the other.
The main screen consists of 24 characters by 12 lines and allows data to be set for each character. The sub-screen consists of 24 characters by 12 lines or up to 32 characters by 16 lines. Data can be set either for each line in the former configuration or collectively for the entire screen in the latter configuration. The characters supported by the MB90092 are the normal characters made up of 24 by 32 dots and the 8 × 32-dot graphic characters that can be displayed in any of eight different colors in character units. If filled with only graphic characters, the main screen is 192 (horizontal) × 384 (vertical) dots. In the same case, the sub-screen is 192 (horizontal) × 384 (vertical) dots, or 256 (horizontal) × 512 (vertical) dots. (The actual display screen depends on the dot clock frequency in the horizontal direction and on the number of rasters of the television system in the vertical direction.) The MB90092 uses RAM as font memory, enabling free graphics display. The MB90092 can use up to 16384 types of characters including normal and graphic characters in total. It can control up to 16M bits of external font memory.
For output of video signals, the MB90092 has the composite video signal, Y/C-separated video signal, and RGB digital output pins. The MB90092 also has video signal input pins, allowing superimpose display over either composite video signals and Y/C-separated video signals.