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The NEC uPD7720 Graphics Display Controller (GDC) is an intelligent microprocessor peripheral designed to be
the heart of a high-performance raster-scan computer graphics and character display system.
Positioned between the video display memory and microprocessor bus, the GDC performs the tasks needed to generate the raster display and manager the display memory. Processor software overhead is minimized by the GDC's sophisticated instruction set, graphics figure drawing, and DMA transfer capabilities. The display memory supported by the GDC can be configured in any number of formats and sizes up to 256K 16-bit words. The display can be zoomed and panned, while partitioned screen areas can be independently scrolled. With its light pen input and multiple controller capability, the GDC is ideal for advanced computer graphics applications. |
The APC can actually use *two* NEC 7220 graphics display controllers, one for text and one for graphics,
the outputs of which are mixed and fed to a single screen. Screen resolution is 640x494,
with the top text line devoted to a time/date display. You can turn this line off and display
graphics in that area, but you can't display your own text there.
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