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

Ask an Expert

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

Write your message here..

Related Questions

8237 modes-microprocessor, 8237 modes : Intel 8237 can be set to four d... 8237 modes : Intel 8237 can be set to four different type of style of transfer: 1) Single - One transfer at a time,  it allow processor access to the bus between transfers

General data registers-microprocessor, General Data Registers Given fig... General Data Registers Given figure indicate the register organization of 8086. The registers DX, CX, BX and AX are the general purpose 16-bit registers. AX is behaved as 16-bi

Using straight line method for depreciation, Request a depreciation of the... Request a depreciation of the item, year of purchase, cost of item, number of years to be depreciated (estimated life ) and,the method of depreciation . Method of depreciation sh

Evolution of microprocessor , EVOLUTION OF MICROPROCESSOR : ... EVOLUTION OF MICROPROCESSOR : The digital circuits and systems may be broken into two part: 1) Sequential Circuit and 2) Combinational Circuits     Norm

Input output interface-microprocessor, I/O interface I/O  devices such ... I/O interface I/O  devices such as displays and keyboards  establish  communication of computer with outside world. Devices may be interfaced in 2 ways Memory mapped I/O and I/

Write an assembly language program, Your assignment for this project is to ... Your assignment for this project is to write an assembly language program that checks if the user's input is a valid ISBN number. A sample run of your program might look like:

Relocate program and data, ) What is the difference between re-locatable pr... ) What is the difference between re-locatable program and re-locatable data?

The 486, The 486 Introduced in the year 1989 the 80486 did not feature ... The 486 Introduced in the year 1989 the 80486 did not feature any radically new processor technology. Instead, it joints a 386 processor, a cache memory controller and a math c

Estimation of a definite integral, Can any one assist me with this program.... Can any one assist me with this program. I am not efficient with assembly language and I need assistance badly. I am not asking anyone to do my work I just need help step by step

Write a mips assembly language program, Write a MIPS/SPIM assembly language... Write a MIPS/SPIM assembly language program that prints the smallest and largest values found in a non-empty table of N word-sized integers. The address of the first entry in your