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

.., Sum of series of 10 numbers and store result in memory location total

Sum of series of 10 numbers and store result in memory location total

8086 minimum mode system and timing-microprocessor, 8086 Minimum mode Syst...

8086 Minimum mode System and Timing In a minimum mode 8086 system, the microprocessor 8086 is operated in minimum mode by strapping its MN/MX pin to logic 1.All the control si

Iret-loop-unconditional branch instruction-microprocessor, IRET : Return f...

IRET : Return from ISR:- When an interrupt service routine is called, before transferring control to it, the IP, CS  register and flag registers are stored in the stack to ment

Add-arithmetic instruction-microprocessor, ADD:  Add :- This instruction ...

ADD:  Add :- This instruction adds an immediate contents of a memory location specified in the a register ( source ) or instruction to the contents of another register (destinat

Read architecture:look aside cache-microprocessor, Read Architecture : Look...

Read Architecture : Look Aside Cache In "look aside" cache architecture the main memory is located conflictingthe system interface. Both the cache main memory sees a bus cycle

Cryptography, Write a program that allows a user to encrypt/decrypt a mess...

Write a program that allows a user to encrypt/decrypt a message using a shift cipher. The user should specify the key and the message. Your program should be able to handle messa

Cmps-string manipulation instruction-microprocessor, CMPS : Compare String...

CMPS : Compare String Byte or String Word:-The CMPS instruction may be utilized to compare two strings of Words or byte. The length of the string ought to be stored in the CX. If

Cache controller-microprocessor, Cache controller The cache controller ...

Cache controller The cache controller is the mind of the cache.  Its responsibilities include:  performing the  snarfs and snoops, updating the  TRAM  and SRAM and implementing

Assebmly code, You have to write a subroutine (assembly language code using...

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

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