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Should any device be allowed to interrupt CPU while another interrupts are being serviced?
Wiki User
∙ 14y ago
It is possible to allow nested interrupts. This is often done when there is a heirarchy of interrupts, some with higher priority than others. In order for this to work, the second interrupt must not be allowed to influence the progress of the first interrupt. We call this being "thread safe". In a nested scheme, an interrupt mask is set so that higher priority interrupts can be permitted, while blocking interrupts of the same or lower priority, and then interrupts are reenabled during the interrupt service routine. At the conclusion of the first routine, interrupts are disabled again, the mask is restored, and the normal interrupt return sequence is executed.
In the 8085, this can be supported using the Read Interrupt Mask (RIM) and Set Interrupt Mask (SIM) instructions. While not strictly required, the logical priority is often INTR, RST5.5, RST6.6, RST7.5, and then TRAP, in order of increasing priority.
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∙ 14y ago
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Briefly compare active and passive multiprogramming?
When a program that is being processed by the CPU issues an I/O command, control is passed to the I/O processor and the CPU is freed to process other programs. This is known as passive multiprogramming. The problem with this, is that the interruptions are primarily controlled by the programs and not the CPU. As an answer to this problem, the CPU was given the control with the advent of active multiprogramming. Active multiprogramming enabled a program to use a preset slice of CPU time before putting the program on hold to process another program. This became the advent of CPU time slicing and became the foundation for time-sharing systems in the 1960's and forward.Active is to do something with energy, while passive is to accept what comes without putting much effort forth.
How would you design an algorithm for reversing two adjacent entries on a stack if you were given three stacks and you were only allowed to move entries one at a time from one stack to another?
Research Towers Of Hanoi http://en.wikipedia.org/wiki/Tower_of_Hanoi You will find your answer
Why is smoke coming out of a heating system from the outside?
If it is white "smoke" then it is probably not smoke at all but only water vapour that is being cooled as it enters the cold air outside the house. It is nothing to worry about as long the heating system is working normally and also as long as you are having the heating system serviced every year by a licensed HVAC (Heating, Ventilation and Air Conditioning) engineer.Black or blue smoke coming out is another matter altogether and could indicate a dangerous fault in the system. If you see that kind of smoke coming out it is time to call a licensed HVAC engineer to inspect the system and advise you what should be done.
Is every class in java is subclass of itself?
A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.
What is another name for propagation delay?
Another name for propagation delay is latency.
What happens when processor is attending an interrupt if it gets another interrupt?
The response to another interrupt request during servicing of an interrupt depends on the setting of the interrupt enable flag and/or the interrupt mask. If the interrupt service routine is thread safe, it will process correctly. More probably, problems will arise so the proper procedure is to either set the interrupt mask (8085) to not allow this or lower priority interrupts before reenabling interrupt, or to leave interrupts disabled until this iteration is complete. If interrupts are disabled or masked, a subsequent interrupt will be posted but not processed until the first is completed.
What is an maskable intErrupt?
interrupts in 8085 are basically classified into two types: 1.Maskable 2.Non maskable maskable interrupts are those which can be delayed.This is done by masking off the interrupts which are not required. Maskable interrupts are:RST 7.5,RST 6.5,RST 5.5 and INTR <decreasing order of priority>
When an interrupt is serviced then what happens if another interrupt is raised?
It depends on the CPU architecture. Most modern CPUs support several levels of interrupts ranging from high priority to low. If the first interrupt that occurred was a high priority, then a lower priority one occurs, the high priority will continue to execute until it is done, then the the CPU will immediately jump to the lower one. Conversely, if the lower priority interrupt occurred first, it will be interrupted until the higher interrupt is serviced. For 80x86 series processors, do not confuse priority with vector. You may remember in the older days interrupt 13 belonging to the hard drive, and interrupts 3 and 4 being part of the serial port. This is not a function of the CPU but of the interrupt controller. The function of this device is beyond the scope of my answer here. 80x86 has 2 interrupt sources: maskable and non-maksable. Think of the non-maskable as the higher priority and the maskable as the lower. Most peripherals use the maskable interrupt line. Although a few, often functions of the BIOS, Fault, or Paged/Protected mode make use of the non-masked interrupt.
What is interrupt mechanism?
At the beginning of each FDE cycle, each bit in the interrupt register is checked in turn. This register is a special register in the CPU that takes note of when an interrupt has happened. Each bit in the register represents a different kind of interrupt. If a bit has been set, that would indicate an interrupt has happened! The CPU has to decide whether to service the interrupt immediately, or leave it till later. For example, if 2 interrupts have happened at the same time, one of them has to wait! Which one? That depends upon which one is the least important! Some interrupts are more important than others and so need to be done before others. What about the situation where one interrupt is currently being serviced by the CPU and another happens? Again, it depends on how important the new interrupt is compared to the one already being done. If it is more important, then the cpu will want to service it immediately. When the CPU decides to service an interrupt, it stops processing the current job, 'pushing' the contents of its registers onto the stack. This would include, for example, the contents of the Program Counter and the accumulator. The CPU is now free to work on another piece of software but can return to what it was doing after the interrupt has been serviced because it has saved where it was. It then transfers control to the interrupt handling software for that type of interrupt using the vectored interrupt mechanism. When it has finished servicing the interrupt, the contents of the stack are 'popped' back into the appropriate registers and the CPU continues from where it left off before the interrupt happened.
How are multiple interrupts dealt with?
There are 2 approaches to handle this situation,1.Disable interrupts while an interrupt is being processingin this approach, when the processor is being processing an interrupt, the processor ignores any new interrupt signal and these new signals have to wait in a queue and processor will check after the currently processing interrupt is finished.2. Defining priorities for interruptsin this case, each interrupt has a priority value. When the processor is being executing an interrupt, another interrupt can interrupt and gain the processor if the second interrupt has a higher priority than first oneSource- William Stallings, operating systems Sorry, the word you are looking for is not in the Database
Interrupt initiated transfer and data transfer under program control?
Program control Interrupt:-Program interrupt can be described as a transfer of program control form a currently running program to another service program on a request generated externally or internally. After the service program is executed the control returns to the original program. It is imperative for the CPU to return to the same state that it was when interrupt occurred after the program interrupted and the service routine has been executed. The state of the CPU at the end of the executive cycle(when the interrupt is recognized )is determined from:1. The content of the program counter. 2. The content of all processor registers. 3. The content of certain status conditions.Interrupts can be classified into the major types as below:-1. External interrupts:- this is come from input output devices, from a timing device, from a circuit monitoring the power supply, or from any other external source. 2. Internal Interrupts:- this is arise when an instruction or data is used illegally or erroneously. These interrupts are also known as traps. 3.Software interrupts:-external and internal interrupts r occur in the hardware of the CPU. A software interrupt is initiated during execution of an instruction. Software interrupts is a special call instruction that behaves like an interrupt rather than a subroutine call. It can be called to function by the programmer to intitiate an interrupt procedure at any desired pointing the program.ReagrdsRaj Choudhary (kajla 9950645563)
What is an interrupt and how are multiple interrupts dealt with?
An Interrupt is a signal that goes into a microprocessor that tells it something has happened that needs attention. There are generally dedicated pins on the microprocessor, often called "Int" (for Interrupt) and "NMI" (for Non-Maskable Interrupt). For a microprocessor, an interrupt signal is like the bell on a telephone is for you; it's a notice that you should stop what you are doing now and deal with this issue that has come up. Exact procedures for dealing with an interrupt vary from one microprocessor to another; generally, the microprocessor puts out a signal that says "Where should I go, then?" and a piece of hardware, the Interrupt Controller, then responds with a signal that tells it which condition has happened. The processor then starts processing the indicated piece of code, and that piece of code handles the condition. The Interrupt Controller often handles setting priority for interrupts, accepting a number of signals (often four), and setting priorities on each. It will trigger another interrupt in the middle of processing one if the new interrupt is a higher priority than the one that is already being processed, or will hold on to the lower priority one until the CPU is finished with a higher-priority one. The CPU can often "disable interrupts" when it is doing something time-critical. At such times, the only interrupt that can occur is the Non-Maskable Interrupt, which is generally reserved for critical error conditions that have to be dealt with immediately no matter what else is going on.
What is the difference between interrupt and system call?
A processor executes its instructions one after another. One of the instructions it can execute is a subroutine call, where it suspends executing the current set of instructions, goes off and executes another set and then returns. This is referred to as 'calling a subroutine.' A 'system call' is a call to a subroutine built into the system, rather than a call to one in your own program. Calls and interrupts work similarly, in that to process an interrupt, the processor goes off and executes a different set of instructions and returns. However, calls are synchronous, they occur in fixed order determined by the program, and the processor only has to remember where it was so it can return to the proper place. Interrupts are asynchronous, they can occur at any time, such as when you hit a key on the keyboard, thus the processor has to remember its place and its state, because the interrupt likely has nothing to do with what it was doing at the time of the interrupt.Disturbing other
Would you use the imperfect tense to talk about an action that interrupts another?
... false
When the shadow of one celestrial body interrupts the view of another the phenomenon is a?
eclipse
What is another word for refrain?
Avoid, pass, Interrupt.
What is interrupt in architecture?
program interrupt is transfer program control from currently running program to a service program depends on internal or external generated request after execution of service program, program control will be returned to original program
