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Read the text and translate it into Ukrainian. In this type of system, a low-level piece of code switches between tasks or threads based on a timer (connected to an interrupt)

In this type of system, a low-level piece of code switches between tasks or threads based on a timer (connected to an interrupt). This is the level at which the system is generally considered to have an "operating system" kernel. Depending on how much functionality is required, it introduces more or less of the complexities of managing multiple tasks running conceptually in parallel.

As any code can potentially damage the data of another task (except in larger systems using an MMU) programs must be carefully designed and tested, and access to shared data must be controlled by some synchronization strategy, such as message queues, semaphores or a non-blocking synchronization scheme.

Because of these complexities, it is common for organizations to buy a real-time operating system, allowing the application programmers to concentrate on device functionality rather than operating system services, at least for large systems; smaller systems often cannot afford the overhead associated with a generic real time system, due to limitations regarding memory size, performance, and/or battery life.

Microkernels and exokernels

A microkernel is a logical step up from a real-time OS. The usual arrangement is that the operating system kernel allocates memory and switches the CPU to different threads of execution. User mode processes implement major functions such as file systems, network interfaces, etc.

In general, microkernels succeed when the task switching and intertask communication is fast, and fail when they are slow.

Exokernels communicate efficiently by normal subroutine calls. The hardware, and all the software in the system are available to, and extensible by application programmers.

Monolithic kernels

In this case, a relatively large kernel with sophisticated capabilities is adapted to suit an embedded environment. This gives programmers an environment similar to a desktop operating system like Linux or Microsoft Windows, and is therefore very productive for development; on the downside, it requires considerably more hardware resources, is often more expensive, and because of the complexity of these kernels can be less predictable and reliable.

Common examples of embedded monolithic kernels are Embedded Linux and Windows CE.

Despite the increased cost in hardware, this type of embedded system is increasing in popularity, especially on the more powerful embedded devices such as Wireless Routers and GPS Navigation Systems. Here are some of the reasons:

Ports to common embedded chip sets are available.

They permit re-use of publicly available code for Device Drivers, Web Servers, Firewalls, and other code.

Development systems can start out with broad feature-sets, and then the distribution can be configured to exclude unneeded functionality, and save the expense of the memory that it would consume.

Many engineers believe that running application code in user mode is more reliable, easier to debug and that therefore the development process is easier and the code more portable.

Many embedded systems lack the tight real time requirements of a control system. A system such as Embedded Linux has fast enough response for many applications.

Features requiring faster response than can be guaranteed can often be placed in hardware.

Many RTOS systems have a per-unit cost. When used on a product that is or will become a commodity, that cost is significant.

2. Read the text and answer the questions.

 

1. What is based on a timer?

2. Why must programs be carefully designed and tested?

3. What must be controlled by some synchronization strategy?

4. Why do organizations buy a real-time operating systems?

5. What does a real-time operating system allow the application programmers to do?

6. What is a microkernel?

7. What is the usual arrangement?

8. What do user mode processes implement?

9. What can you say about exokernels?

10. 10)What type of embedded system is increasing in popularity?

11. 11)What are the reasons for this?

 


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