SEARCH
You are in browse mode. You must login to use MEMORY

   Log in to start

level: Operating System

Questions and Answers List

level questions: Operating System

QuestionAnswer
To bridge the user and the computer hardware, since the user cannot communicate with the hardware directlyWhat is the purpose of an operating system?
- Control Hardware - Manage software (loading into RAM) - Provide security (username and password) - User interface - Processor schedulingName 5 functions of an operating system
- Kernel - Drivers - User Interface - System UtilitiesName the 4 main parts of an OS
Paging is fixed size (4Kb) segments, segmentation is varying length segmentsWhat's the difference between paging and segmentation (mention exact size where necessary)
- Pages are fixed sizeWhat is one difference between pages and segments?
The allocation of segments or sections of memory to allow a process to runWhat is memory segmentation?
Suspends the execution of the current process, puts the values of the Program Counter and the other registers onto the stack temporarily, completes the task, then loads the values back into the registers from the stack and continues as beforeWhat happens when an interrupt occurs?
Efficiently and fairly allocating CPU time to different tasks to allow for multi-tasking. Usually smaller parts of multiple tasks are executed in succession to give the appearance of carrying out several tasks simultaneouslyWhat is processor scheduling?
Each process is given a limited amount of CPU time (time slice). If the process isn't completed before it's time expires, the despatcher gives the CPU the next processHow does Round Robin scheduling work?
To compensate for the difference in speed between the peripheral and the CPUwhat is the point of a buffer (in the context of peripheral management)
The memory manager determines the least used page and copies it into virtual memory. The free area is re-numbered by the memory manager and marked as free for use(paging) What happens if RAM is full but more pages are needed?
Quickly loading and unloading things from RAMWhat causes disk thrashing?
When memory locations get 'locked up' because the data isn't properly flushed so the memory manager thinks it's still in useWhat is a memory leak?
When a stack gets too full and runs out of free memory to useWhat is stack overflow?
At the end of each fetch-decode-execute cycleWhen does the CPU check for interrupts?
When the CPU regularly checks if an event or peripheral needs attentionWhat is polling?
When all registers are copied to the stack before executing an interruptWhat is context switching?
Stack overflow because each paused instruction is put in the stack until it is resumed so eventually the stack can overflowWhat is a risk of too many interrupts interrupting other interrupts?
- Doesn't take into account how important a process is - Doesn't consider that some processes are long and some are shortWhat are 2 disadvantages of round robin scheduling?
Each one is allowed to complete before moving onWhat is first come first served scheduling?
- Doesn't account for processing time - Doesn't account for priorityWhat are 2 disadvantages of first come first served scheduling?
Maximum number of jobs completed quickly but long jobs may never complete if shorter jobs keep interruptingWhat is one good thing and one bad thing about shortest job first scheduling?
Shortest Time RemainingName the scheduling algorithm which fixes shortest job first's problem
Multi level feedback queueWhat scheduling technique takes priority into account?
Multi-tasking OSWhat is this type of OS called? - Windows, Linux, MacOS
Allocates each workstation timeHow do multi-user OS' allow multiple workstations to access the mainframe?
Multiple computers all being controlled by one OS and sharing a task (spreading the workload)What is a distributed OS?
- It must respond very quickly to any inputs or sensors - It must be able to deal with many inputs simultaneously - It must have "failsafe" mechanisms to detect and take appropriate action if a hardware component fails - It must incorporate redundancy - if one component fails, it needs to automatically switch to backup hardware - Used on planes and factory production linesWhat are the 4 required features of a real-time OS and what are 2 examples of somewhere a realtime OS would be used?
- ATM - Washing Machine - CarName 3 devices with embedded OS
The low-level real-time operating system in charge of radio and other hardware has system vulnerabilitiesWhat is a problem with smartphones having 2 operating systems?
Boot up the computer - test the hardware and load the OSWhat is the purpose of BIOS?
Basic Input Output SystemWhat does BIOS stand for?
Non-volatile flash memory on the motherboardWhere is BIOS usually stored?
Running more than one OS on a computerWhat is a use of a virtual machine?
Provides a software interface to a particular hardware deviceWhat's the point of a driver?
Systems Software and Application SoftwareSoftware can be grouped into two categories, what are they?
Software needed to run the computer's hardware and application programs - this includes operating system, utility programs etc.What is systems software?
Analysis, Design, Implementation, Evaluation, MaintananceWhat are the 5 stages of development?
Defining the problem that the system must solve and looking at current competition and problems etcWhat is the Analysis section of software development?
Designing the actual systemWhat is the Design stage of software development?
In black box testing the internal structure/design/implementation of what's being tested isn't known by the tester, in white box testing it isWhat's the difference between black box and white box testing?
The coding and testing will be carried out and errors will be traced and correctedWhat happens in the implementation stage of software development?
effectiveness, usability and maintainabilityWhat are the three factors on which the product is evaluated in the evaluation stage?
A relational database concept which states that table relationships must always be consistent - e.g. a foreign key must be consistent with the primary key that it's referencingWhat is referential integrity?
Inline, embedded and external style sheetWhat are the 3 methods of implementing CSS?