I/O software in modern operating systems consists of four distinct layers. Quest
ID: 3908705 • Letter: I
Question
I/O software in modern operating systems consists of four distinct layers. Question 8 (2, 4) WO software in modern operating systems consists of four distinct layers. a. What are these layers, and why is the layered architecture necessary? b. In which of the four layers is each of the following done: 1. Computing the track, sector, and head for a disk read. 2. Writing commands to the device registers. 3. Checking to see if the user is permitted to use the device. 4. Converting binary integers to ASClI for printing. Justify your answer for each point.Explanation / Answer
Answer:
The operating system and application can (and regularly are) made themselves out of various layers:
1. Equipment
2. System BIOS
3. Operating System
4. Application
Every one of these layers adds to similarity in a fundamental way: it converses with the level beneath it utilizing a standard interface. All together for Word 6.0 to work in Windows, it must take after specific guidelines put forward by the architects of Windows. Windows must take after tenets put forward by the makers of DOS. What's more, DOS must utilize an institutionalized method for conversing with the system BIOS.
Each layer gives a reflection model to the product that keeps running on it, by giving to the layer above it an arrangement of administrations and capacities that the layer above it can utilize. Word 6.0 doesn't stress over the equipment or DOS much by any stretch of the imagination; it basically calls Windows capacities and gives Windows a chance to stress over DOS. Windows converses with DOS utilizing DOS capacities, and so forth. (This is to some degree rearranged on the grounds that sometimes the layers aren't this neatly isolated).
By utilizing these guidelines, it makes it conceivable to blend and match different layers, as long as the software engineers take after the tenets. In the event that you need to refresh your DOS adaptation, Windows will in any case fill in as long as the new DOS form gives a similar standard interface that the old one did; it can give new capacities, however not take away any of the old ones. Essentially, Word 6.0 will chip away at Windows 95 on the grounds that Windows 95 gives similar offices to Word that Windows 3.x did. This is the manner by which similarity is kept up crosswise over changes to operating systems.
What does this need to do with the BIOS? The BIOS is really the column that backings the majority of this, since it gives the standard interface that DOS utilizes (or whatever the operating system is). The system equipment itself is the "chaos at the base of the heap" that we are attempting to need to abstain from managing. In some ways, the most astonishing piece of the majority of this is DOS itself will keep running on such a large number of various machines. The BIOS is the thing that makes this conceivable. Rather than DOS talking specifically to the equipment, of which there are many, numerous potential outcomes. It converses with the BIOS, which is what is tweaked to the equipment. The BIOS conceals the equipment from the operating system so it doesn't need to stress over it, by giving institutionalized administrations to the operating system.
As suggested above, programs don't generally need to take after this model precisely. It is feasible for a DOS program to sidestep DOS and the BIOS capacities, and interface straightforwardly with the equipment. This is done ordinarily for execution reasons; diversions do it regularly. The issue is that this breaks the similarity model; now the product has to make sense of what equipment it is utilizing, and this makes these kinds of projects considerably less versatile and perfect than ones that "play by the tenets".
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