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What happens when an interrupt occurs while in halt?
This halt allows peripheral devices to access the microprocessor. Whenever an interrupt occurs the processor completes the execution of the current instruction and starts the execution of an Interrupt Service Routine (ISR) or Interrupt Handler.
What happens if some exception occurs while executing certain instruction?
Whenever an exception or interrupt occurs, the hardware starts executing the code that performs an action in response to the exception. The instructions responsible for this action reside in the operating system kernel, and the code that performs this action is called the interrupt handler code.
Is halt an interrupt?
Halt is a cessation (stop), either temporary or permanent, while interrupt is to disturb or halt an ongoing process or action by interfering suddenly.
What is the purpose of halt in basic instruction cycle?
In the x86 computer architecture, HLT (halt) is an assembly language instruction which halts the central processing unit (CPU) until the next external interrupt is fired. Interrupts are signals sent by hardware devices to the CPU alerting it that an event occurred to which it should react.
What is the sequence of events when an exception occurs?
C++ exception handling is built upon three keywords: try, catch, and throw. throw − A program throws an exception when a problem shows up. This is done using a throw keyword. catch − A program catches an exception with an exception handler at the place in a program where you want to handle the problem.
What is necessary to exit from the halt state?
An interrupt or reset is necessary to exit from the halt state.
What is the purpose of the halt instruction?
On Motorola CPUs, the HALT instruction was called STOP and took an argument: A value written to the status register (which holds, among others, the Interrupt mask) – So you could specify for which interrupt to wait (Or, rather, the minimum IPL (Interrupt Priority Level) that has to occur before execution resumes).
How is the halt instruction like executing NOPs?
Keep in mind, it’s not executing NOPs, it’s just like executing NOPs. HALT is a single instruction, and the PC will already have advanced to the next instruction after it has been read in M1. Thus an accepted interrupt will push the address of the next instruction and when POPed, execution continues there.
What happens to the program counter when an interrupt occurs?
The current Program Counter is saved on the stack, low-byte first. Interrupts of the same and lower priority are blocked. In the case of Timer and External interrupts, the corresponding interrupt flag is cleared.
What happens when an interrupt is triggered in a microcontroller?
When an interrupt is triggered, the following actions are taken automatically by the microcontroller: The current Program Counter is saved on the stack, low-byte first. Interrupts of the same and lower priority are blocked. In the case of Timer and External interrupts, the corresponding interrupt flag is cleared.