Vital Windows Programing Interview Preparation Guide

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► Selects from among the processes in memory that are ready to execute, and allocates the CPU to one of them.
► CPU scheduling decisions may take place when a process:
1.Switches from running to waiting state.
2.Switches from running to ready state.
3.Switches from waiting to ready.
4.Terminates.
► Scheduling under 1 and 4 is nonpreemptive.
► All other scheduling is preemptive.

LDAP, Lightweight Directory Access Protocol, is an Internet protocol that email and other programs use to look up information from a server.

INODE is a pointer to a block on the disk and it is unique.
Inode is an unique number. Inode holds metadata of files.

A real time process is a process that must respond to the events within a certain time period. A real time operating system is an operating system that can run real time processes successfully

Kernel objects are owned by the kernel, not by a process

► Amoeba
► WinNT
► Minix

A single process can have multiple threads that share global data and address space with other threads running in the same process, and therefore can operate on the same data set easily. Processes do not share address space and a different mechanism must be used if they are to share data.

If we consider running a word processing program to be a process, then the auto-save and spell check features that occur in the background are different threads of that process which are all operating on the same data set (your document).

process:
In computing, a process is an instance of a computer program that is being sequentially executed[1] by a computer system that has the ability to run several computer programs concurrently.

Thread:
A single process may contain several executable programs (threads) that work together as a coherent whole. One thread might, for example, handle error signals, another might send a message about the error to the user, while a third thread is executing the actual task of the...

Kernel object data structures are accessible only by the kernel.

The number of threads a process can create is limited by the available virtual memory and depends on the default stack size

A thread uses the CreateMutex function to create a mutex object. The creating thread can request immediate ownership of the mutex object and can also specify a name for the mutex object

Threads in other processes can open a handle to an existing named mutex object by specifying its name in a call to theOpenMutex - function. Any thread with a handle to a mutex object can use one of the wait functions to request ownership of the mutex object. If the mutex object is owned by another thread, the wait function blocks the requesting thread until the owning thread releases the mutex object using theReleaseMutex - function.

A microcontroller is by definition a is a computer on a chip. It includes all the necessary parts (including the memory) all in one IC. You just need to apply the power (and possibly clock signal) to that device and it starts executing the program programmed to it. A microcontroller generally has the main CPU core, ROM/EPROM/EEPROM/FLASH, RAM and some necessary functions (like timers and I/O controllers) all integrated into one chip. The original idea behind the
microcontroller was to limit the capabilities of the CPU itself, allowing a complete computer (memory, I/O, interrupts, etc) to fit on the available silicon real estate.
Microcontrollers are typically used where processing power isn't so important. More important are generally compact construction, small size, low power consumption and that those chips are cheap. For example controlling a microwave oven is easily accomplished with the smallest of microcontrollers. There is countless number of small
electronic devices which are nowadays based on microcontroller. A modern home can include easily tens or hundreds of microcontrollers, as almost every modern device which has electronics have a microcontroller (or more than one) inside.
Microprocessor is generally just the CPU core itself, although nowadays it might have some accessory parts also integrated to the same chip

Semiconductor memories are of two types: RAM (random access memory) and ROM (read only memory).
RAM is a read/write memory. Information can be written into and read from a RAM. It is volatile memory.
It stores information so long as power supply is on.
ROM is permanent type memory. Its contents are not lost when power supply goes off. the user cannot write into a ROM.Its contents are decided by the manufacturer and written at the time of manufacture. Programmable ROMs are also available. They are called PROMs.

Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. This task is known as a context switch. Context-switch time is pure overhead, because the system does no useful work while switching. Its speed varies from machine to machine, depending on the memory
speed, the number of registers which must be copied, the existed of special instructions(such as a single instruction to load or store all registers).

Main memory:
only large storage media that the CPU can access directly.

Secondary storage:
extension of main memory that provides large nonvolatile storage capacity.

Dispatcher module gives control of the CPU to the process selected by the short-term scheduler; this involves:
Switching context
Switching to user mode
Jumping to the proper location in the user program to restart that program
Dispatch latency ? time it takes for the dispatcher to stop one process and start another running.

The most important reason was robustness. If kernel object handles were system-wide values, one process could easily obtain the handle to an object that another process was using and wreak havoc on that process. Another reason for process-relative handles is security. Kernel objects are protected with security, and a process must request permission to manipulate an object before attempting to manipulate it. The creator of the object can prevent an unauthorized user from touching the object simply by denying access to it

Several types of kernel objects, such as access token objects, event objects, file objects, file-mapping objects, I/O completion port objects, job objects, mailslot objects, mutex objects, pipe objects, process objects, semaphore objects, thread objects, and waitable timer objects.

Waiting state

Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.

Specification of the task
Design of algorithms
Implementation (coding)
Testing and debugging
Maintenance and evolution of the system
Obsolescence

Distribute the computation among several physical processors.
Loosely coupled system each processor has its own local memory; processors communicate with one another through various communications lines, such as high-speed
buses or telephone lines
Advantages of distributed systems:
► Resources Sharing
► Computation speed up load sharing
► Reliability
► Communications

The number of days before a deleted object is removed from the directory services. This assists in removing objects from replicated servers and preventing restores from reintroducing a deleted object. This value is in the Directory Service object in the configuration NIC

by default 2000 (60 days)

Synchronization object s are use to co-ordinate the execution of multiple threads. Which kernel objects are use for Thread Synchronization on different processes? - Event, Mutex, Semaphore

An interpreter reads one instruction at a time and carries out the actions implied by that instruction. It does not perform any translation. But a compiler translates the entire instructions.