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10/13 10/8 OS作業
名稱	10/8 OS作業
日期	10/13
課程名稱	作業系統
指導教師	劉艾華

1.
reduce the wating time of CPU and raise the efficiency of system

CPU can read all most dates by cache without all ways read by slower divice

if the program start change 2 dates without stoping then those two date will occupy the cache so the efficiency of cache will be slow down

if the cahce capacity more larger and it will makes mistakes by compulsion

2.
An interrupt is a hardware-generated change of flow within the system.
An interrupt handler is called to deal with the cause of the interrupt;control is then returned to the interrupted context and instruction. A trap is a software-generated interrupt. An interrupt can be used to signal the completion of an I/O to obviate the need for device polling.
A trap can be generated intentionally by a user program. It can be used to call operating system routines or to catch arithmetic errors.

3.
Each device controller has a local buffer and a command register. It communicates with the CPU by interrupts. A device's controller plays an important role in the operation of that device; it functions as a bridge between the device and the operating system.
A CPU uses complex algorithms and programming to interpret signals and code.A CPU retrieves information from the code within programs. It reads it to understand what the code is for, and then it executes the instructions.
They use binary and digital codes.

4.
Each interrupt has its own interrupt handler. The number of hardware interrupts is limited by the number of interrupt request (IRQ) lines to the processor, but there may be hundreds of different software interrupts. Interrupts are a commonly used technique for computer multitasking, especially in real-time computing.

更新日期：2015/10/15 上午 12:12:10