Q1 : How is RTOS different from other OS?
A : RTOS offers services that allow tasks to be performed within predictable timing constraints.
Q2 : Why do we require semaphore?
A : For process synchronization, it is a mechanism to invoke the sleeping process to become ready for execution. Its mechanism where a process can wait for resources to be available. typical example is producer consumer process. The producer process creates resources and signals the semaphore saying resource is available. Consumer process waiting on the semaphore gets the signal that resource is available.
Q3 : What are the SDKs developed by winCE?
A : MSFT standard SDK’s are,
1. Windows Mobile for Smartphone = Windows Mobile Standard.
2. Windows Mobile for Pocket PC = Windows Mobile Classic.
3. Windows Mobile for Pocket PC Phone Edition = Windows Mobile Professional.
Q4 : In RTOS having 1okbytes of memory and your program for asking for 5kbytes and you got null error? why does it behave like this?
A : RTOS might be having 10k memory, might not fragmentation problem, and the largest hole available to user might be lesser than 5k, this condition might be one of the reason for NULL error.
Q5 : What are the different interprocess communications?
A : Semaphore, mutex, message passing, shared memory, socket connections.
Q6 : What is CE Stands in winCCE?
A : In the name “Windows CE,” the letters “CE” are not an abbreviation for anything, but rather they imply a number of the precepts around which Windows CE is designed, including “Compact,” Connectable,” Compatible,” “Companion,” and “Efficient.”
Q7 : What is caching?
A : Caching is the processing of utilizing a region of fast memory for a limited data and process. A cache memory is usually much efficient because of its high access speed.
Q8 : Is Unix a multitasking or multiprocessing operating system?what’s the difference between the two?
A : UNIX is a multitasking operating system, multiprocessing means it can run on multiple processors, the multiprocessing os coordinates with multiple processors running in parallel.
Q9 : What are the advantages and disadvantages of winCE compared to GPOS?
A : Advantages:
1) Supports various types of processor platforms
2) Possible to Customize the Kernel and can reduce its size (up to ~300KB kernel size)
3) Especially for the embedded device platforms
Disadvantages:
1) Process limits, max. 32 process at a time in WinCE 5.0
2) Limited space allocation for each processes, 32MB/each process
Q10 : What is multitasking?
A : Multitasking is the process within an operating system that allows the user to run several applications at the same time. However, only one application is active at a time for user interaction, although some applications can run “behind the scene”.
Q11 : What is the need of creating 4GB of pages in Linux?
A : Well, the simple answer is it can address so much of memory with available 32 address lines. 2 ^ 32 = 4 GB.
Q12 : What are the different types of semaphores in vxworks RTOS? Which is the fastest?
A: VxWorks supports three types of semaphores.
1) Binary 2) mutual exclusion, and 3)counting semaphores.
Fastest : Binary semaphore.
Q13 : What is kernel?
A : A kernel is the core of every operating system. It connects applications to the actual processing of data. It also manages all communications between software and hardware components to ensure usability and reliability.
Q14 : What are the primary functions of VFS?
A : VFS, or Virtual File System, separate file system generic operations from their implementation by defining a clean VFS interface. It is based on a file-representation structure known as vnode, which contains a numerical designator needed to support network file systems.
Q15 : What is the purpose of an I/O status information?
A : I/O status information provides information about which I/O devices are to be allocated for a particular process. It also shows which files are opened, and other I/O device state.
Q16 : What is the root partition?
A : Root partition is where the operating system kernel is located. It also contains other potentially important system files that are mounted during boot time.
Q17 : When does thrashing occur?
A : Thrashing refers to an instance of high paging activity. This happens when it is spending more time paging instead of executing.
Q18 : What is the basic function of paging?
A : Paging is a memory management scheme that permits the physical address space of a process to be noncontiguous. It avoids the considerable problem of having to fit varied sized memory chunks onto the backing store.
Q19 : Briefly explain FCFS.
A : FCFS stands for First-come, first-served. It is one type of scheduling algorithm. In this scheme, the process that requests the CPU first is allocated the CPU first. Implementation is managed by a FIFO queue.
Q20 : What is time- sharing system?
A : In a Time-sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can interact with each program while it is running.