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A raster interrupt is a computer interrupt signal that is used for display timing purposes. It is usually, though not always, generated by the system's graphics chip. On some platforms the feature is called Horizontal Blank Interrupt (HBI). Often, the graphics chips used in home computers and video game consoles had limited capabilities. Raster interrupts were incorporated into these video chips allowing skilled programmers to transcend these limitations. A software-serviced interrupt would be set to trigger when a given screen line was refreshed, and the interrupt routine could then reload the chip's registers. In doing so, the graphics chip state could be changed at a specific screen position allowing sprites to be repositioned, additional colors inserted, or graphics modes to be changed giving the graphics hardware the appearance of greater capability than it was inherently endowed. Several popular home computers and video game consoles included graphics chips supporting raster interrupts or had features that could be combined to work like raster interrupts. Dates below reflect the year the chips were designed/committed to silicon. == Atari's ANTIC (1978) == The ANTIC chip used by the Atari 8-bit family includes display list interrupts (DLIs), which perform much the same function as raster interrupts. The ANTIC chip itself is considerably powerful and inherently capable of many features which other systems require raster interrupts to duplicate. ANTIC can mix multiple graphics modes on the screen, display horizontal and vertical overscan graphics, and fine scroll selected horizontal regions. DLIs on the Atari are typically used to add additional color to the display and reuse Player/Missile graphics elements (aka: sprites). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Raster interrupt」の詳細全文を読む スポンサード リンク
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