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What is the important aspect of a real-time system or Mission Critical Systems?
A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some...
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What is cache memory?
Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory.
thukral.rahul
- Jan 12th, 2010
A Cache is a fast memory (generally SRAMS) that is genearally installed between the main memory and disk to reduce the transfer rate and access time disparities.
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Differentiate between Complier and Interpreter?
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.
Sandhya.Kishan
- Apr 23rd, 2012
The compiler converts a high level language instruction into into machine language where as an interpreter converts the high level instruction into some intermediate form and after that, the instructi...
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What are different tasks of Lexical Analysis?
The purpose of the lexical analyzer is to partition the input text, delivering a sequence of comments and basic symbols. Comments are character sequences to be ignored, while basic symbols are character sequences that correspond to terminal symbols of the grammar defining the phrase structure of the input
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Why paging is used?
Paging is solution to external fragmentation problem which is to permit the logical address space of a process to be noncontiguous, thus allowing a process to be allocating physical memory wherever the latter is available.
Sandhya.Kishan
- Apr 23rd, 2012
Paging is a process of dividing the memory into equal sized logical blocks.When any page is required the operating system searches for that page in the secondary memory and copies that page to the mai...
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What are the main difference between Micro-Controller and Micro- Processor?
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)...
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What is Context Switch?
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...
Sandhya.Kishan
- Apr 23rd, 2012
Context switching is a process of storing and restoring the state of the CPU So that the execution of the process can be resumed from the same point where it had been switched. There are 3 situations ...
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Common Functions of Interrupts?
->Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines.->Interrupt architecture must save the address of the interrupted instruction.->Incoming interrupts are disabled while another interrupt is being processed to prevent a lost interrupt.->A...
rakesh trichy
- Oct 12th, 2008
8051:InterruptNumber Description Address0 EXTERNAL INT 0 0003h1 TIMER/COUNTER 0 000Bh2 EXTERNAL INT 1 0013h3 TIMER/COUNTER 1 001Bh4 SERIAL PORT 0023heg program..unsigned int interruptcnt;unsigned cha...
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Difference between Primary storage and secondary storage?
Main memory: – only large storage media that the CPU can access directly.Secondary storage: – extension of main memory that provides large nonvolatile storage capacity.
rakesh trichy
- Oct 12th, 2008
Primary is were the operating system and other files are stored which is usually the hard drive. Secondary is a second hard drive or a CD/DVD ROM or 3 1/4 inch floppy drive or any other type of devic...
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While running DOS on a PC, which command would be used to duplicate the entire diskette?
diskcopy Java Thread States
Sandhya.Kishan
- Apr 23rd, 2012
Diskcopy command is used to duplicate the diskette,while running DOS on PC.
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What is CPU Scheduler?
->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.
rakesh trichy
- Oct 12th, 2008
Disk schedulers in current operating systems are generally work-conserving, i.e., they schedule a request as soon as the previous request has finished. Such schedulers often require multiple outstandi...
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What is Memory-Management Unit (MMU)?
->Hardware device that maps virtual to physical address.In MMU scheme, the value in the relocation register is added to every address generated by a user process at the time it is sent to memory.->The user program deals with logical addresses; it never sees the real physical addresses.
rakesh trichy
- Oct 12th, 2008
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware component responsible for handling accesses to memory requested by the central processing u...
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Define Demand Paging, Page fault interrupt, and Trashing?
Demand Paging: Demand paging is the paging policy that a page is not read into memory until it is requested, that is, until there is a page fault on the page. Page fault interrupt: A page fault interrupt occurs when a memory reference is made to a page that is not in memory.The present bit in the page table entry will be found to be off by the virtual memory hardware and it will signal an interrupt. Trashing:...
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Root Directory
The root directory of disk should be placed 1. at a fixed address in main memory 2. at a fixed location on disk 3. anywhere on the disk 4. at a fixed location on the system disk
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List of CPU Scheduling algorithms implemented in Windows Operating System
Hi As we all Know that the OS use various CPU Scheduling algorithm's. I would like to know what Algorithms are used in various OS(Specially in Windows OS) and the purpose.Thank You Julie
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Briefly explain about the differences between the concepts that are involved in Windows and UNIX operating system?
rakesh trichy
- Oct 11th, 2008
Unix is more flexible and can be installed on many different types of machines, including main-frame computers, supercomputers and micro-computers.- Unix is more stable and does not go down as often ...
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Windows Interview Questions
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