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

Hiring problem algorithm, Consider the Hire Assistant problem. We interview...

Consider the Hire Assistant problem. We interview n candidates and always hire the best qualified so far. Let n = 5 for our example. Find the probabilities that we hire exactly 1 t

Draw a diagram to explain major components of web browser, Draw a neat diag...

Draw a neat diagram to explain major components of a web browser. The Major Component of a Web browser A browser contains a set of clients, a controller and a set o

Definition of decision support system, Q. Definition of Decision support sy...

Q. Definition of Decision support system? Definition of DSS: A decision support system is a specific kind of information system which is an interactive system that supports in

Explain rational robots coding standards, The standards are for all testers...

The standards are for all testers using the IDE of Rational Robot to make their automated test scripts. The mission is to decrease maintenance costs when it comes to changes.

General principles of pruning, General principles of pruning: The gene...

General principles of pruning: The general principles are such that: 1. Given a node N that can be chosen by player one, thus if there is another node, X, along any path,

First order predicate logic-artificial intelligence, First Order Predicate ...

First Order Predicate Logic This is a more expressive logic because it builds on propositional logic by allowing us to use constants, predicates, variables, quantifiers and fun

Final year project, i want to make final year project in wireless.please he...

i want to make final year project in wireless.please help me to decide the topic???????

Displaying a number, Displaying a number Supposing that two digit num...

Displaying a number Supposing that two digit number 59 is stored as number 5 in BH and number 9 in BL to convert them to equivalent ASCII we will add "0" to each one of them.

Explain open source software, Explain Open source software? Open Source...

Explain Open source software? Open Source Software is software for which the underlying programming code is available to the users so that they might be read it, make changes t

Describe the functionality of software testing, What do you do if you have ...

What do you do if you have given functionality that wasn't listed in the requirements? - If the functionality isn't essential to the purpose of the application, it should be re

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