Interrupt table-how interrupt table processed-microprocessor, Assembly Language

Interrupt Table

Each interrupt level has a booked memory location, called an interrupt vector.  All these vectors (or pointers) are stored in the interrupt table. Table lies at linear address zero, or with 64KB segments, at 0000:0000. Every vector is two words long (4 bytes). The high word has the offset and the low word the segment of the INT handler.

How INT's are Processed :

Since there are 256 levels and each vector is 4bytes long so the table contains 1024 bytes (256*4=1024). The INT number is multiplied by four to fetch the address from the table.               

Whenever the CPU registers an INT it will push the FLAGS register to the stack and also push the IP and CS registers.  After that the CPU deactivates the interrupt system.  Then it acquires the 8-bit value the interrupting device sends and multiplies this by four to acquire the offset in the interrupt table. From this offset it acquires the address of the INT handler and carries over execution to this handler.

Usually the handler enables the interrupt system immediately to let interrupts with higher priority. Some devices also require a signal that the interrupt has been acknowledged. When the handler is stop (terminated) it might signal the 8259A PIC with an EOI (End of Interrupt). Then handler executes an IRET instruction.

 

Posted Date: 10/10/2012 8:19:25 AM | Location : United States







Related Discussions:- Interrupt table-how interrupt table processed-microprocessor, Assignment Help, Ask Question on Interrupt table-how interrupt table processed-microprocessor, Get Answer, Expert's Help, Interrupt table-how interrupt table processed-microprocessor Discussions

Write discussion on Interrupt table-how interrupt table processed-microprocessor
Your posts are moderated
Related Questions
64-bit integer calculator, which processes using 16-bits at a time (reg/mem16 operands)

The real time System (RTS) : Calling the clock real-time is somewhat of a misnomer because it only shows the time setting it has been given. The RTC is the other half of chip

Assembly Language: Inside the 8085, instructions are really stored like binary numbers, not a very good manner to look at them and very difficult to decipher. An assembler is

You have to write a subroutine (assembly language code using NASM) for the following equation.

Write a program to calculate the first 20 numbers of Fibonacci series. Use the stack (memory) to store the calculated series. Your debugger output should look like the following sc

SBB: Subtract  with Borrow  :- The subtract with borrow instruction subtracts the source operand and the borrow flag (CF) which might reflect the result of the past calculations,

Project Overview In this series of projects you will write a compiler for a small subset of Pascal.  In this assignment, you will start writing the syntax analysis and code gen

AAS: ASCII Adjust AL After Subtraction AAS instruction correct the result in the AL register after subtracting operation of two unpacked ASCII operands. The result is in unpacked

Write a procedure to read a text file and copy its contents to another text file using 8086 assembly language .

what will be the value of EAX after following instructions execute? mov bx, 0FFFFh and bx, 6Bh