Posted on Categories:OS操作系统, 计算机代写

avatest™

OS操作系统操作系统（OS）是管理计算机硬件、软件资源的系统软件，并为计算机程序提供公共服务。时间共享的操作系统为系统的有效使用安排任务，也可能包括用于处理器时间、大容量存储、打印和其他资源成本分配的会计软件。对于硬件功能，如输入输出和内存分配，操作系统作为程序和计算机硬件之间的中介，尽管应用程序代码通常由硬件直接执行，并经常对操作系统功能进行系统调用或被其打断。操作系统出现在许多包含计算机的设备上–从移动电话和视频游戏机到网络服务器和超级计算机。

avatest.™OS操作系统代写，免费提交作业要求， 满意后付款，成绩80\%以下全额退款，安全省心无顾虑。专业硕 博写手团队，所有订单可靠准时，保证 100% 原创。avatest.™， 最高质量的OS操作系统作业代写，服务覆盖北美、欧洲、澳洲等 国家。 在代写价格方面，考虑到同学们的经济条件，在保障代写质量的前提下，我们为客户提供最合理的价格。 由于统计Statistics作业种类很多，同时其中的大部分作业在字数上都没有具体要求，因此OS操作系统作业代写的价格不固定。通常在经济学专家查看完作业要求之后会给出报价。作业难度和截止日期对价格也有很大的影响。

avatest.™ 为您的留学生涯保驾护航 在计算机Computers代写方面已经树立了自己的口碑, 保证靠谱, 高质且原创的计算机Computers代写服务。我们的专家在OS操作系统代写方面经验极为丰富，各种OS操作系统相关的作业也就用不着 说。

In many current systems, the CPU contains multiple cores, which means it can run several processes at the same time. In addition, each core is capable of multitasking, which means it can switch from one process to another quickly, creating the illusion that many processes are running at the same time.

The part of the operating system that implements multitasking is the kernel. In a nut or seed, the kernel is the innermost part, surrounded by a shell. In an operating system, the kernel is the lowest level of software, surrounded by several other layers, including an interface called a “shell.” Computer scientists love extended metaphors.

It’s hard to specify which parts of the operating system should be in the kernel. But at its most basic, the kernel’s job is to handle interrupts. An interrupt is an event that stops the normal instruction cycle and causes the flow of execution to jump to a special section of code called an interrupt handler.

A hardware interrupt is caused when a device sends a signal to the CPU. For example, a network interface might cause an interrupt when a packet of data arrives, or a disk drive might cause an interrupt when a data transfer is complete. Most systems also have timers that cause interrupts at regular intervals.

A software interrupt is caused by a running program. For example, if an instruction cannot complete for some reason, it might trigger an interrupt so the condition can be handled by the operating system. Some floatingpoint errors, like division by zero, can be handled using interrupts.

## 计算机代写|OS操作系统代考OS operating system代写|Hardware state

Handling interrupts requires cooperation between hardware and software. When an interrupt occurs, there might be several instructions running on the $C P U$ and data stored in registers.

Usually the hardware is responsible for bringing the CPU to a consistent state; for example, every instruction should either complete or behave as if it never started. No instruction should be left half complete. Also, the hardware is responsible for saving the program counter (PC), so the kernel knows where to resume.

Then, usually, it is the responsibility of the interrupt handler to save the contents of the registers. In order to do its job, the kernel needs to execute instructions, which modify data registers and the flag register. So this hardware state needs to be saved before it gets modified, and then restored before the interrupted process resumes.
Here is an outline of this sequence of events:

1. When the interrupt occurs, the hardware saves the program counter in a special register and jumps to the appropriate interrupt handler.
2. The interrupt handler stores the program counter and the flag register in memory, along with the contents of any data registers it plans to use.
3. The interrupt handler runs whatever code is needed to handle the interrupt.
4. Then it restores the contents of the saved registers. Finally, it restores the program counter of the interrupted process, which has the effect of jumping back to the interrupted instruction.

If this mechanism works correctly, there is generally no way for the interrupted process to know there was an interruption, unless it detects small changes in the time between instructions.

. txt

.使用实例

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。