Operating system basic Question

Question 1:

                   Some CPUs provide for more than modes operation. What are two possible uses of these multiple modes?

Answer:

 Although most system only distinguish between user and kernel modes, some CPUs have supported multiple modes. Multiple modes could be used to provide a finer-grained security policy. For example rather than distinguishing between just user and kernel mode, you could distinguish between different types of user mode. Perhaps user belonging to the same group could execute each other’s code. The machine would go into a specified mode when one of these user was running code. When the machine was in this mode, a member of the group could run belonging to anyone else in the group

Another possibility would be to provide different distinction within kernel code. For example a specific mode could allow USB device drivers to run. This would mean that USB device could be serviced without having to switch to kernel mode, thereby essentially allowing USB device drivers to run in a quasi-user/kernel mode

Question 2:

                     Describe some of the challenges of designing operating system for mobile device compared with designing operating system for traditional PCs.

Answer:

     The greatest challenges in designing mobile operating systems include:

· Less storage capacity means the operating system must manage memory carefully.

· The operating system must also manage power consumption carefully.

· Less processing power plus fewer processors mean the operating system must carefully apportion

processors to applications.

Question 3:

(i)

What does Bootstrap mean?

 Answer:

A bootstrap is the process of starting up a computer. It also refers to the program that initializes the operating system (OS) during start-up.

The term bootstrap or bootstrapping originated in the early 1950s. It referred to a bootstrap load button that was used to initiate a hardwired bootstrap program, or smaller program that executed a larger program such as the OS. The term was said to be derived from the expression “pulling yourself up by your own bootstraps;” starting small and loading programs one at a time while each program is “laced” or connected to the next program to be executed in sequence.

Major component of boot strap process

  GNU grand unified boot loader (GRUB): a multiboot specification that allows the user to choose one of several OS.

  NT loader(NTLDR)

linux loader(LILO)

  Network interface controller(NIC)

A microsoft windows operating system bootstrap process runs "NT loader (NTLDR)" as we use already discuss ,while linux loader (LILO) runs the linux operating ststem