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 .net and .net framework, What is .NET / .NET Framework?  It i...

What is .NET / .NET Framework?  It is a Framework in which Windows applications might be developed and run. The Microsoft .NET Framework is a platform for building, deploying,

Give the syntax of if-else statement, Give the syntax of "if-else" and "sw...

Give the syntax of "if-else" and "switch" statements and explain. if else This is used to decide whether to do something at a special point, or to decide between two courses

Btree, What should the size of ''t'' in btree be depending on the hard disk...

What should the size of ''t'' in btree be depending on the hard disk size

What is response ratio, What is response ratio? HRRN that is Highest Re...

What is response ratio? HRRN that is Highest Response Ratio Next scheduling is a non-preemptive discipline, as same to Shortest Job First (SJF) wherein the priority of all jobs

What are packages, What are packages? Package is a group of elements (c...

What are packages? Package is a group of elements (classes, generalizations, associations and lesser packages) with a common theme. Package partitions a model making it simpler

Posix threads and mutex, The objective of this practical assignment is to u...

The objective of this practical assignment is to use the POSIX environment to write a program that simulates the supply and demand between three processes: warehouse, factory and r

State about CSMA/CA, State about CSMA/CA It belongs to a class of proto...

State about CSMA/CA It belongs to a class of protocols known as multiple access methods. CSMA/CA  stands  for:  Carrier  Sense  Multiple  Access  with  Collision Avoidance.  In

Generalization-specialization(DBMS), Design a generalization-specialization...

Design a generalization-specialization hierarchy for a motor vehicle sales company. The company sells motorcyles,passenger cars,vans,and buses.justify your placement of attributes

Application to calculate weekly payment of a company, Problem: A compa...

Problem: A company requires a software application to calculate the weekly payment for its employees. The information about the employees (employees' data) is kept in a file.

Components of flash, A piece of art can be looked at as having 3 main compo...

A piece of art can be looked at as having 3 main components, the subject, the composition and the content. Subject The subject of an artwork is, in simple terms, the object

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