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

Why use a DTD (Document Type Definition), Why use a DTD ( Document Type Def...

Why use a DTD ( Document Type Definition )? XML gives an application independent method of sharing data. Along with a DTD, independent group of people can agree to employ a com

Explain conditions for the critical section problem solution, What are the ...

What are the properties which a data item should possess to implement a critical section? The Critical Section Problem Solution should satisfy the following conditions: 1.

What are the steps involved in authentication, What are the steps involved ...

What are the steps involved in authentication? Steps in Authentication The control over the access of the resources in the repository is exercised in two steps namely Auth

Why a linked list is called a dynamic data structure, Why a linked list is ...

Why a linked list is called a dynamic data structure? What are the advantages of using linked list over arrays?    A linked list is known as a dynamic data structure because it

Features of hyper-threading, The salient features of hyper threading are: ...

The salient features of hyper threading are: i)  Improved support for multi-threaded code, permitting multiple threads to run concurrently. ii) Response time and improved rea

What is immediate addressing, What is Immediate addressing The  data  i...

What is Immediate addressing The  data  itself,  beside  the address,  is  given  as  the  operand or operands  of  the instruction.

Push and pop, i want flowchart for push, pop in stack element and display s...

i want flowchart for push, pop in stack element and display stack and exit

What is perl, Perl is an interpreted language (not compiled, like Java) whi...

Perl is an interpreted language (not compiled, like Java) which is ideally suited for CGI programming. It has its roots in UNIX system administration and offers various features li

Structure of internet servers address, Structure of Internet Servers Addres...

Structure of Internet Servers Address Structure of an Internet server's address keyed into a client's software is as below: http://www.expertsmind.com Where: htt

Dynamic screen sequence, Dynamic screen sequence  for a  screen can be set ...

Dynamic screen sequence  for a  screen can be set using which commands? It uses two commands:- A) Set Screen B) Call screen.

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