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

Machine code, do you type assembly code or machine code instructions like b...

do you type assembly code or machine code instructions like b8 0100000 to add to register EAX straigt onto dos command line or do you have to same in a file and what extension woul

Scanning, how o create the flow chart for scan ROW4, Column 1 and 3.tq

how o create the flow chart for scan ROW4, Column 1 and 3.tq

LAB homework, 1. Write a program that calculates the Fibonacci series: 1, 1...

1. Write a program that calculates the Fibonacci series: 1, 1, 2, 3, 5, 8, 13, ….. (Except for the first two numbers in the sequence, each number is the sum of the preceding two n

Assembling a program-microprocessor, Assembling a program Microsoft Ass...

Assembling a program Microsoft Assembler MASM is one of the simple to use and famous assemblers.  All the references and discussions in this section are belonging to the MASM.

Display control-microprocessor, Display control 8279  provides  a  16  ...

Display control 8279  provides  a  16  byte  display  memory  and  refresh  logic.  Every address in the display memory corresponds to a display unit with address zero represen

Assembler directives and operators-microprocessor, Assembler Directives and...

Assembler Directives and Operators The major advantage of machine language programming is directly that the memory control is in the hands of the programmer, so that, he can be

Intel 8259 interrupt controller-microprocessor, Intel 8259 interrupt contro...

Intel 8259 interrupt controller :  The 8088 processor has only two interrupt control inputs, and interrupt request (INTR) and non mask able interrupt (NMI). NMI are interrupts t

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

4 bit 2s complement multiplier, How to design 4 bit signed 2s complement m...

How to design 4 bit signed 2s complement multiplier?

Write an assembly language program, You are to write an assembly language p...

You are to write an assembly language program called subfaq.s that computes the generalized subfactorial function of nonnegative integer inputs i0 and n. The generalized subfactori

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