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

Assignment Help:

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.

 


Related Discussions:- Interrupt table-how interrupt table processed-microprocessor

Program to perform one byte bcd addition-assembly program, Program : Write...

Program : Write a program to perform a one byte BCD addition. Solution : It is consider that the operands are in BCD form, but the CPU considers it as hexadecimal and acco

Assembly - Zombie Game using Irvine & Visual 2010, http://www.raritanval.ed...

http://www.raritanval.edu/uploadedFiles/faculty/cs/full-time/Brower/CISY256/2013Spring/CISY256%20Assembly%20Project.pdf

Port mapped or mapped input output, Port Mapped I/O or I/O Mapped I/O I...

Port Mapped I/O or I/O Mapped I/O I/O devices are mapped into a separate address space. This is generally accomplished by having a different set of signal lines to denote a mem

ROTATION, CANI GET HELP WRITTING THIS CODE

CANI GET HELP WRITTING THIS CODE

Segmentation, segmentation and overlapping in assemble language

segmentation and overlapping in assemble language

Xor-logical instruction-microprocessor, XOR: Logical Exclusive OR: The XOR...

XOR: Logical Exclusive OR: The XOR operation is again carried out in a similar way to the AND and OR operation. The constraint over operands are also similar. The XOR operation pr

Code for reading flow & generating serial output, Assembly Code for Reading...

Assembly Code for Reading Flow & Generating Serial Output The timer is timer 1 is set for the baud rate 9600, as the crystal used is of 11.0592 Hz.  Then the timer 1 is starte

Compute the fibonacci sequence - assembly program, Compute the Fibonacci se...

Compute the Fibonacci sequence - assembly program: Problem: Fibonacci   In this problem you will write a program that will compute the first 20 numbers in the Fibonacci sequ

Program, assembly language program to find larges number in an array

assembly language program to find larges number in an array

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd