Vectored interrupts are a mechanism used in computer systems where each interrupt is assigned a unique vector, or address, that points to a specific interrupt service routine (ISR). When an interrupt occurs, the processor uses the vector to quickly locate the corresponding ISR in memory, allowing for efficient handling of the interrupt. This method speeds up the interrupt handling process by eliminating the need for the processor to search through a table of ISRs. Call locations for these vectors are typically defined in a specific area of memory, often known as the interrupt vector table.
When an interrupt is pending, the processor will temporarily halt its current execution to address the interrupt signal. It saves the state of the current process, including the program counter and registers, to ensure that it can resume later. The processor then jumps to the interrupt service routine (ISR) associated with the interrupt to handle the specific event. Once the ISR completes, the processor restores the saved state and resumes the interrupted process.
In the 8085 microprocessor, a hardware interrupt is a signal from an external device that temporarily halts the CPU's current operations to allow the device to communicate with the processor. A vector interrupt specifically refers to an interrupt that has a predefined memory address (vector) associated with it, which the processor jumps to when servicing the interrupt. For instance, the 8085 has several hardware interrupts, such as INTR, RST 7.5, RST 6.5, and RST 5.5, each with its own unique vector address, allowing for efficient and organized handling of multiple interrupt sources. This mechanism enables real-time processing and responsiveness to external events in embedded systems.
An interrupt makes the processor to jump to a vectored location in memory where the ISR is written. By observing the vectored locations for various interrupt inputs of 8085, we know that there are only 4 or 8 bytes allocated for ISR. This memory space is not sufficient for writing any code to process an interrupt. So we write a jump instruction that makes the processor jump to a location in user memory and write the ISR starting from that location.Example: suppose there is an interrupt signal to 8085 at RST 6.5. The call location for RST 6.5 is 0034H. The address space available is 4 bytes. So if we write instruction jmp 2300H at 0034H, then we can write ISR in memory locations starting from 2300H.
In computing, an autovector is an interrupt vector representing a priority level, from which the processor determines the target address.
Vector interrupt --> when processor directly call the respective isr when interrupt occurs so, address of respective isr is usually save in register. Non interrupt Vector --> In this case when interrupt occurs the processor calls a generic isr and in generic isr uaer has to call respective isr by checking status register.
In the 8086 microprocessor, the register that stores the interrupt and subroutine return address is the Instruction Pointer (IP) register. When an interrupt occurs or a subroutine is called, the current instruction address is pushed onto the stack, allowing the processor to return to that location after the interrupt or subroutine execution is complete. The IP register works in conjunction with the Code Segment (CS) register to determine the effective address of the next instruction to execute.
An interrupt vector is the memory address of an interrupt handler, or an index into an array called an interrupt vector table or dispatch table. Interrupt vector tables contain the memory addresses of interrupt handlers. When an interrupt is generated, the processor saves its execution state via a context switch, and begins execution of the interrupt handler at the interrupt vector.
When the 8086 microprocessor receives an interrupt signal, it completes the execution of the current instruction and saves the address of the next instruction onto the stack. It then determines the appropriate interrupt vector from the Interrupt Vector Table (IVT) based on the interrupt type. The processor then transfers control to the interrupt service routine (ISR) associated with that interrupt. After the ISR has executed, the 8086 retrieves the saved address from the stack and resumes execution from where it was interrupted.
when interrupt occurs, the program counter content will stores into stack, an PC will load interrupt address for next instruction execution. ofter completion ISR process PC will retrieves the stack values and execution will be continued.
When a processor is interrupted to do a particular task,Program counter should be loaded with the the address of subroutine(task).If the processor automatically generates the address then it is known as vectored interrupt.for example if 8085 microprocessor is interrupted through RST 5.5 pin,then processor multiplies 5.5 by 8 and converts it to Hex address.If user has to provide address of subroutine using CALL instruction then it is known as non vectored interrupt
When a TRAP interrupt is triggered, program control is transferred to a specific location in the interrupt vector table, typically defined by the system architecture. This location contains the address of the interrupt service routine (ISR) that handles the TRAP. The CPU saves the current program state, including the program counter, before jumping to the ISR, ensuring that the original program can resume after the interrupt is processed.