Stack operation and interrupts in microprocessor, Computer Engineering

Assignment Help:

Let us review the operation of the stack within the 68HC11, the stack is a defined area of RAM which is last in first out register (LIFO) . Access to the stack is made via a stack pointer (SP). In the 68HC11 there is only one stack pointer and it is initialised by the LDS command. To transfer data onto the stack we can use the command PSHA or PSHB i.e. push register A or B onto the stack. To remove data simply pull it i.e PULA or PULB, likewise the index registers may be stacked  etc.

      PSHA Push A onto Stack
      PSHB  Push B onto Stack
      PSHX  Push X onto Stack
      PSHY  Push Y onto Stack
      PULA Pull A onto Stack
      PULB  Pull B onto Stack
      PULX  Pull X onto Stack
      PULY  Pull Y onto Stack

Every time data is 'Pushed' onto the stack the Stack pointer is decrements accordingly. The stack is used often by the micro controller for temporary holding data, if a subroutine occurs, the processor stacks the return address and upon the receipt of the RTS command, it pulls the return address automatically. During an interrupt the processor stacks the full details of itself i.e.

  SP    Condition code  
  SP-1    Accumulator A
  SP-2    Accumulator B
  SP-3    Index register X high
  SP-4    Index register X low
  SP-5    Index register Y high
  SP-6    Index register Y low
  SP-7    return address High
  SP-8    Return address Low 
  SP-9    Stack pointer after interrupt

Therefore great care should be taken when using the stack as during an interrupt or subroutine if you place data on the stack you must remove the data before you return from it.


Related Discussions:- Stack operation and interrupts in microprocessor

What is smtp, SMTP is a Protocol used for transferring message among en...

SMTP is a Protocol used for transferring message among end user & Mail Server.

Workday versus oracle, Workday has set the stage to revolutionize the way c...

Workday has set the stage to revolutionize the way companies manage and facilitatevarious aspects of their business operationsby utilizing cutting-edge cloud-based technologies in

Logical representations in artificial intelligence, Logical Representations...

Logical Representations: If every human being spoke the same kind of language, there would be several less misunderstanding in the world. The problem with software engineering

What is swapping, What is swapping?   A process can be swapped out tempo...

What is swapping?   A process can be swapped out temporarily of memory to a backing store and after that brought back in memory for execution as continued.

Show the Features of parallel virtual machine, Q. Show the Features of para...

Q. Show the Features of parallel virtual machine? Easy to install; Easy to configure; Multiple users each can use PVM concurrently; Multiple applications fro

What is file scope, Explain File scope File scope: The variables and ...

Explain File scope File scope: The variables and functions with file scope appear outside any block or list of parameters and are accessible from any place in the translation

Program that will blink as led, Take the last two digits of your UTCID. Thi...

Take the last two digits of your UTCID. This is your duty cycle in percent. If your duty cycle is less than 10%, add 30 to your number. Create an assembly program that runs on t

Define functionality of application layer in tcp/ip protocol, Define the fu...

Define the functionality of application layer in TCP/IP protocol stack? Function of Application Layer: The top layer within the Internet reference model is the applicatio

Intelligent systems assignment, This logbook should be used to record decis...

This logbook should be used to record decisions, ideas, work done by your group on this assignment. Each group should keep one logbook, which must be submitted along with your sour

What is missing offset, Q. What is Missing offset? The xxxx in machine ...

Q. What is Missing offset? The xxxx in machine language for instruction at line 0010 is there since the assembler doesn't know DATA segment location which will be determined at

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