問72
頻出度★☆☆
コンピュータを構成する一部の機能の説明として，適切なものはどれか。
平成21年度 秋期 ITパスポート試験 問72
テクノロジ系コンピュータ構成要素 › プロセッサ
This question's explanation and your answers so far.
解説
問 72
- ア
正解 The five major functions of a computer are input, storage, arithmetic/logic, control, and output. Among these, only the control function acts as the commander that issues instructions. The control function fetches an instruction from the storage function, decodes it, and sends control signals telling the arithmetic/logic function, the storage function, and the input/output functions what to do. The arithmetic/logic function follows those instructions to carry out computation such as the four arithmetic operations and logical operations, and returns the result to the storage function. Therefore choice ア, which says the arithmetic/logic function performs computation according to instructions from the control function, is appropriate.
Incorrectイ
Incorrect. The arithmetic/logic function basically exchanges data with the storage function (main memory). Data entering through the input function is first stored in the storage function; the arithmetic/logic function reads it from storage, processes it, writes the result back to storage, and from there it is passed to the output function. Saying that the arithmetic/logic function exchanges data directly with the input and output functions does not match the data flow of the five major functions. Also, what it exchanges with the control function is control signals, not data.
Incorrectウ
Incorrect. The storage function has the passive role of holding data and instructions; it is not in a position to request processing from other functions. It is the control function that issues the instruction to perform computation. The latter half, holding the result of computation, is correct, but the first half, the storage function requesting computation, is wrong, so the choice as a whole is inappropriate.
Incorrectエ
Incorrect. It is the control function that instructs the output function to output the data held in the storage function. The storage function is the side that hands over data after receiving an instruction; it does not issue commands to the output function on its own. Here too, the entity that issues instructions is mistaken for the storage function.
ここがポイント
- The five major functions of a computer are input, storage, arithmetic/logic, control, and output. Only the control function is the commander that sends instructions (control signals) to the others; the arithmetic/logic, storage, input, and output functions all act on those instructions.
- The basic data flow is input to storage to arithmetic/logic to storage to output. The arithmetic/logic function exchanges data by way of the storage function, not directly with the input and output functions.
用語