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Operating Systems Test 1
Test 1
29
Computer Science
Undergraduate 3
10/03/2013

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Cards

Term
What are the goals of an OS Design?
Definition
The goals of OS design are to make the computer more convenient to use, to allow the system resources, and permit effective development.
Term
What is the Kernel of an OS?
Definition

The kernel controls the execution of the processors.

It manages thread scheduling

process switching

exception and interrupt handling

and multilevel process synchronization.

Term
What are the responsibilities of an OS with regard to resource management?
Definition
Tracks the status of resources.
Determines who gets what resources.
Allocates resources.
Retrieves resources.
Term
Explain the difference between monolithic kernel and microkernel.
Definition
Monolithic: include most of the functionality it the OS. Is a single process with elements sharing the same address space.
Microkernel: Only a few essential functions are in the kernel. Other services are provided by processes that run in user mode.
Term
What is the PCB (Process Control Block).
Definition
The PCB is a data structure that stores information for processes. It is the main tool to allow interrupts and multiprocessing.
Term
What is swapping and what is its purpose?
Definition
Swapping is the process that switches the contents of an area in main stores with an area in secondary memory. When process are not ready they get swapped into secondary memory, then a new process is brought into the main.
Term
Why do we need dual mode of operation?
Definition
The reason we need duel mode operation is so that we can protect kernel mode processes such as the PCB's from being interfered with by user programs.
Term
What is the difference between an interrupt and a trap?
Definition
Interrupt: An external process that is brought about by the clock, I/O, or a memory fault.

Trap: A trap is an error or exception in the currently running process. If the condition is fatal the process moves to an exit state.
Term
What are the advantages of ULT's (user level threads) over KLT's (kernel level threads)?
Definition
Thread switching does not require kernel mode.
Scheduling can be application specific.
User level threads can run on any OS.s
Term
What are the advantages of KLT's (Kernel level threads) over ULT's (User level threads)?
Definition
When a ULT executes a call on a blocked thread not only is it blocked but all threads in that process are blocked.
In a pure ULT strategy a multithreaded application cannot take advantage of multiprocessing.
Term
What resources are typically shared by all threads of a process?
Definition
Threads of the same process share memory, code section, data section, and OS resources.
Term
What is the basic requirement for the execution of concurrent processes?
Definition
The ability to enforce mutual exclusion.
Term
What is the distinction between competing processes and cooperating processes?
Definition
Competing processes use the same resources. Such as a file.
Cooperating processes share resources and may not be aware of eachother.
Term
What is the difference between a weak and strong semaphore?
Definition
Weak semaphores do not specify what method to remove processes with.
Strong semaphores use a FIFO method to remove processes.
Term
What is the difference between a binary and general semaphore?
Definition
A general semaphore has an integer tracking the number of items in the buffer.
A binary semaphore only has two states, 0 and 1. It is a more restricted version.
Term
What is the difference between blocking and non-blocking with respect to messages?
Definition
Blocking is where the process must wait to receive the message before it continues.
Non-blocking is where the process continues to execute while the message is in transit.
Term
The processor control's the operations of the computer and performs its data processing functions.
T or F
Definition
True
Term
Cache memory is invisible to the Operating System.
T or F
Definition
True.
Term
Interrupts are provided primarily as a way to improve processor utilization.
T or F
Definition
True.
Term
An SMP can be defined as a stand alone computer system with two or more similar processors of comparable capability.
T or F
Definition
True.
Term
The operating system acts as an interface between computer hardware and the human user.
T or F
Definition
False. An operating system acts as an interface between applications and the computer hardware.
Term
The OS frequently relinquishes control and must depend on the processor to allow it to regain control.
T or F
Definition
True.
Term
One of the driving forces in operating system evolution is advancement in the underlying hardware technology.
T or F
Definition
True.
Term
A processor itself is not a resources so the OS is not involved in determining how much of the processor time is devoted to the execution of a user program.
T or F
Definition
False.
Term
A monolithic kernel is implemented as a single process with all elements sharing the same address space.
T or F
Definition
True.
Term
The user has direct access to the processor with a batch-processing type of OS.
T or F
Definition
False.
Term
The phrase "Control is passed to a job" means that the processor is now fetching and executing instructions from the monitor program.
T or F
Definition
False.
Term
Race Condition
Definition
A situation in which multiple threads or processes read and write a share data item and the final result depends on the relative timing of their execution.
Term
Terminating a process does not terminate all threads in that process.
T or F
Definition
True
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