Entries Tagged 'Technology' ↓

The IA-32 architecture, of which the pentium processors are examples uses two interrupt request lines, a non maskable interrupt and a maskable interrupt, also called user interrupt request or INTR. Interrupt requests on NMI are always accepted by the processor. Request on the INTR are accepted only if they have a higher percentage of privilege level than the program currently executing. INTR interrupts can also be enabled or disabled by setting an interrupt- enable bit in the processor status register. In addition to external interrupts, there are many events that arise during program execution that can cause an exception. These include invalid opcodes, division errors, overflow and many others. They also include trace and breakpoint interrupts. The occurnce of any of these events causes the processor to branch to an interrupt service routine. Each interrupt or exception is assigned a vector number.

An OS providesa variety of services to aplication programs. To facilitate the implementation of these services, most processors have several different software interrupt instructions, each with its own interrupt vector. They can be used to call different parts of the OS, depending on the service being requested. Alternatively, a processor may have only one software instruction with an interrupt, and also with an immediate operand that can be used to specify the desired service. In a computer that has both a supervisor and a user mode, the processor uses or switches its operation to supervisor mode at the time it accepts an interrupt request. It does so by setting a bit in the processor status register after saving the old contents of that register on that stack. Thus when an application program calls the OS by a software interrupt instruction, the processor automatically switches to supervisor mode giving the os complete access to the computer’s resources.

The OS is responsible for coordinating all the activities within a computer. It makes extensive use of interrupts to perform I/O operations and communicate with and control the execution of all programs. The interrupt mechanism enabled the operating system to assign priorities, switch from one user program to another, implement security and protection features, and co-ordinate securiy features and activities. We will discuss some of these features briefly. A discussion of OS is outside the scope of this book.

The OS incorporates the interrupt service routines for all devices connected to the computer. Application programs do not perform I/o operations themselves. When an application program needs an input or an output operation, it points to the execution of that program temporarily and performs the requested I/O operation. The OS suspends the execution of that program temporarily and performs the required I/O operations.

Power plants are also known as power station or power generation plants.Indian power plants could be broadly classified as Thermal power plant,diesel power plant or fossil fuel power plant, Hydal power plant or Hydro electric power plant,natural gas power plant,oil power plant, geothermal power plant,Steam power plant or steam turbine power plant,nuclear power plant, gas power plant and coal feeding power plant.The main part regarding a power plant is the power plant construction.It comprises of the steps like power plant design,introduction of new power plant technology,making availability of new power plant parts,power plant raw materials etc. Not only power plant resources are needed power plant experts as well as power plant laborers or power plant workers are needed.Of this power plant managers has an important position.They always check the conditions or stability of numerous power plant equipments.The other factor, the power plant engineering department has to check is that of power plant efficiency.The power plant development depend on the power plant services and it is mainly influenced by the design adopted by the power plant creator.But with the large increase in facilities offered,the power plant cost will reach much higher value.The power plant energy or power plant cost depends on it.Power plantconsultants are available in this field.Now a large number of power plant companies are coming into this field.

A program enters a waiting loop in which it repeatedly tests the device status. During this period, the processor is not performing any useful computation. There are many situations where other tasks can be performed while waiting for an I/O device to become ready. To allow this to happen, we can arrage for the I/O device to alert the processor when it becomes ready. It can do so by sending a hardware signal called an interrupt to the processor. Atleast one of the bus control lines, called an interrupt request line is usually dedicated for most of these kind of purposes. Since the processor is no longer required to continuously check the status of external devices, it can use the waiting period to perform other useful functions. Indeed, by using interrupts such waiting periods can ideally be eliminated.