問53
頻出度★★☆
PC のディスプレイに表示する文字や図形などのデータを格納する専用のメモリはどれか。
平成25年度 秋期 ITパスポート試験 問53
テクノロジ系コンピュータ構成要素 › メモリ
This question's explanation and your answers so far.
解説
問 53
Incorrectア
DVD-Video is a standard for recording video and audio onto a DVD (a usage format for optical discs), not memory. A DVD is an auxiliary storage (external storage) medium that can be removed and carried around, and it does not have the role of holding a display's content pixel by pixel and continuously sending it to the screen.
Incorrectイ
ROM (Read Only Memory) is read-only memory, non-volatile memory whose contents are not lost even when the power is turned off. It is used to store basic programs and data that are not rewritten, such as the BIOS and firmware. Displayed content is rewritten moment by moment, so display data cannot be stored in read-only ROM, and it is not memory dedicated to display on a screen either.
Incorrectウ
Cache memory is high-speed, small-capacity memory that temporarily holds frequently used data and instructions in order to bridge the speed gap between the CPU and main memory. Its purpose is to speed up processing, not screen display, and it is not dedicated memory that holds display data.
- エ
正解 The correct answer is "エ Graphics memory." Graphics memory (VRAM, video memory, video RAM) is dedicated memory for holding one screenful of the picture that the GPU (graphics processing unit) puts on the screen — that is, for holding characters, figures, and images as per-pixel color information. The display is constantly reading out the contents of this memory to refresh what it shows, so rewriting the displayed content is equivalent to rewriting the contents of the graphics memory. The stem's description, "dedicated memory that stores the data to be shown on a display," is exactly the role of graphics memory itself, and the other three are not memory dedicated to display. Note also that the higher the resolution it can handle, and the larger the number of bits of color information per pixel (color depth), the more capacity is required, so high-definition, many-color display needs graphics memory with a large capacity.
ここがポイント
- Graphics memory (VRAM, video memory) = display-dedicated memory that holds the pixel data for one screenful to be shown on the display. The required capacity is obtained as "horizontal pixel count × vertical pixel count × bits per pixel (color depth)" (note that it is proportional not to the number of colors itself, but to the number of bits that expresses the number of colors).
- Distinguishing the roles of the various kinds of memory: ROM (Read Only Memory) = non-volatile and read-only; cache memory = a high-speed buffer that bridges the speed gap between the CPU and main memory; main memory (RAM) = programs and data being executed; graphics memory = for display. DVD-Video is not memory but a video recording standard for optical discs.
用語