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

How is a multidimensional array defined pointer, How is a multidimensional ...

How is a multidimensional array defined in terms of a pointer to a collection of contiguous arrays of lower dimensionality ? C does not have true multidimensional arrays. Howev

Posix, POSIX is the IEEE's Portable Operating System Interface for Computer...

POSIX is the IEEE's Portable Operating System Interface for Computer Environments. The standard provides compliances criteria for operating system services and is designed to allow

Integrated services digital network service, Whole idea of ISDN is to digit...

Whole idea of ISDN is to digitize the telephone network to permit transmission of video, audio and text over existing telephone lines. The purpose of ISDN is to provide fully integ

Communications between the user and the server, Communications between the ...

Communications between the user and the server A significant enhancement was achieved when communications between the user and the server was sent in encrypted form and later

Show library, Show Library and its types. Libraries constitute a simple...

Show Library and its types. Libraries constitute a simple meaning of gathering many object files together: 1. Static: during link editing Library code is integrated with t

CONVERT NUMBER TO ALPHABET, HOW TO CONVERT THE NUMBER INTO ALPHABET USING C...

HOW TO CONVERT THE NUMBER INTO ALPHABET USING C/C++ PROGRAM

Hazard (computer architecture), Hazard (computer architecture): In the...

Hazard (computer architecture): In the computer architecture, a hazard is a possible problem that can occurs in a pipelined processor. It concern to the possibility of erroneo

How do the registers help in instruction execution, Q. How do the registers...

Q. How do the registers help in instruction execution? We will discuss this in following steps: Step 1: First step of instruction execution is to fetch instruction which

Organisational inertia - obstacle to information system, Organisational Ine...

Organisational Inertia - Obstacle To Information System This is most easily understood as problems of change and culture. Like any change process technology led change will be

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