What is device agnosticism? How do I achieve device independence?

The advantages of device independence are: the user has nothing to do with the physical peripherals, and the program does not need to be modified when the system adds, removes or changes the peripherals; It is easy to deal with the failure of input and output equipment, for example, when a line printer fails, it can be replaced by another one, or even different types of equipment such as tape drive or disk drive, so as to improve the reliability of the system, increase the flexibility of peripheral equipment allocation, and can make more effective use of peripheral equipment resources to realize multi-channel programming technology.

After the operating system provides device-independent characteristics, programmers can use logical devices for line input and output, and the conversion between logical devices and physical devices is usually implemented by the operating system's commands or languages. Because the size of the operating system and the function are different, the conversion of the specific realization logic device to the physical device is different, and the following method is generally used: utilize the job control language to realize the device conversion of the batch system, utilize the operation command to realize the device conversion, utilize the high-level language.

to implement the device transformation.

Device independence means that the operating system treats all external devices as if they were files, as long as their drivers are installed.

Any user can manipulate and use these devices in the same way as files, without having to know how they exist.

The realization of the device-independent feature brings two benefits: (1) flexibility in device allocation; (2) Easy to implement IO redirection (refers to the fact that the device used for IO operation can be replaced i.e. redirected without having to change the application.

How to achieve device independence.

In order to achieve device independence, two concepts should be introduced: logical devices and physical devices. In an application, use a logical device name to request the use of a certain type of device; When the system is executed, the physical device name is used. Since the driver is a piece of software that is closely related to the hardware (or device), a layer of software, called device-independent software, must be set up on top of the driver to perform common operations for all devices, complete the conversion of logical device names to physical device names (for which a logical device table should be set up), and provide a unified interface to the user-level (or file-layer) software to achieve device independence.

Device-agnostic: The application is independent of the physical device being used.

Implementation: Change the program's logical and physical devices to non-channel interfaces, setting access rights for each device appropriately.

In order to improve the adaptability and scalability of operating systems, device independence, also known as device independence, is implemented in modern operating systems without exception.

In order to achieve device independence, a layer of software must be set on top of the device driver, known as device-agnostic IO software.

There are many external devices of the computer, and the same type of equipment has different manufacturers and different models of products. There will always be some nuances to these products. This makes it very difficult to write an application, because it is impossible for an application to be compatible with all hardware.

To this end, the operating system isolates the specific hardware device from the entire system, and covers the specific operation of the hardware, hardware-related compatibility issues, etc.

It is solved by the device driver, and at the same time, the operating system provides a unified method for manipulating the device to the application, and the application only needs to call the functions provided by the operating system according to the routine, and does not need to care about what the actual device is, which is independent of the device. This way, every time you add or change hardware to your system, you only need to install the appropriate drivers.