1. Define the concepts interrupt and trap, and explain the purpose of an interru
ID: 3859888 • Letter: 1
Question
1. Define the concepts interrupt and trap, and explain the purpose of an interrupt vector. 2. How does a computer system with von Neumann architecture execute an instruction? 3. What role do device controllers and device drivers play in a computer system? 4. Why do clustered systems provide what is considered high-availability service? 5. Describe an operating system's two modes of operation. 6. Define cache, and explain cache coherency. 7. Describe why direct memory access (DMA) is considered an efficient mechanism for performing I/O 8. Describe why multicore processing is more efficient than placing each processor on its own chip.Explanation / Answer
1.
Trap is a software generated interrupt that is caused by division by zero or invalid memory access which are invalid software routines.
Traps are synchronous.
Interrupt is hardware generated fault that is, it caused by the devices like the hard disk, graphics card, I/O, ports etc. Interrupts are asynchronous.
The memory location of an interrupt handler is given by an interrupt vector and this interrupt handler is generated when the interrupt is called.
2.
In von Neumann architecture reading and writing of the data to and from the main memory is done on one data bus and fetching instructions for execution id done on another data bus. The simple computer design is offered by this architecture. The memory addresses are different in this architecture. In this architecture, the processor has the ALU that can implement the basic functions and operations and it has the temporary storage that can store only a few words of data.
3.
The movement of the data between the peripheral devices and its local buffer storage is done by the device controller. The device driver is a software that runs the device. The device driver acts an interface between the device controller and the operating system. The device is connected to the computer when the device driver is installed on the computer. The most common example of the device driver is the USB driver that is installed in the computers through which the user and the system can communicate with the device.
4.
The clustered system provides the high availability service because in this system a group of hosts provide efficient system by acting as a single system. These clusters are used for load balancing, back up, high availability service because it helps to achieve an enhancement in processing power. In clustered system, the chance of having a single point of failure is eliminated.
5.
The two modes of the operating system are: user mode and kernel mode. The mode in which the system executes on behalf of a user application is called a user mode. The mode in which a user application requests a service from the OS through a system call, is called a kernel mode. The user mode is represented by 1 and the kernel mode is represented by 0.
6.
The cache is the form of the memory that is used if the user references the same data again and again so that it can be accessed faster. The cache is used to store the data that can be referenced by the user again and again. The cache coherence is the consistency of the data that is stored in the cache. This cache coherence is important for multiprocessors or distributed memory systems.
Thus, cache coherency ensures that multiple caches store the most updated version of the stored data. It means that if one CPU alters the data, the cache of other CPU receives an updated version of this data.
7.
The DMA plays an important role in moving data between the devices and main memory. Thus, DMA is efficient as it allows hardware to access memory even if the CPU is busy or already running. It removes the scope of complete dependence on CPU for transferring for transferring data. Since, CPU is not accessed every time the system’s memory has to be accessed, so the time taken for the I/O devices to access system memory is reduced.
8.
The multi-core processing is more efficient than placing each processor on its own chip because it will ensure faster processing because multi-processing means that a chip has two or more processors. Due to multi-processor system, each core can perform its own function independently, irrespective of another processor.
Thus, the multi-processor system ensures efficiency and speed.
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