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

Display data in the combo box, Which property on a Combo Box do you set wit...

Which property on a Combo Box do you set with a column name, prior to setting the Data Source, to display data in the combo box? ComboBox.DataValueField = "ColumnName" When

How is network examined by intranets, How is network examined by intranets,...

How is network examined by intranets, extranets and Internet? When more and more businesses seek to build their mission critical business solutions onto IP networks, networking

Higher order predicate logic - artificial intelligence, Higher Order Predic...

Higher Order Predicate Logic: In first order predicate logic, we are allowed to quantify over objects only. If we let  ourselves  to  quantify  over  predicate  or  function  s

Critical capabilities for superior firm performance, What are the critical ...

What are the critical capabilities for superior firm performance in e-commerce? Three firm capabilities which are critical for superior firm performance within e-commerce are:

What are the digital certificates of hardware computations, What are the Di...

What are the Digital certificates of hardware computations Digital certificates are highly dependent on hardware computations, it is essential that mechanisms are evolved to i

How can we resize layout cells, Q. How can we Resize Layout Cells? To p...

Q. How can we Resize Layout Cells? To precisely design a page, you can set size of cells you add in a document. You can reposition cells in the page as well. 1.      Click o

Formal analysis of visual elements, Formal Analysis: The second step o...

Formal Analysis: The second step of the art critiquing process often begins with an analysis of the artworks formal elements and how they are the organised. The formal elem

What is a heap, What is a heap? A complete binary tree, every of whose ...

What is a heap? A complete binary tree, every of whose elements contains a value that is  greater than or equal to the value of every of its children is known a Heap

Split bus operation - universal serial bus , Split Bus Operation - universa...

Split Bus Operation - universal serial bus :   USB 2.0 devices utilize a special protocol in the reset time that is called "chirping", to negotiate the high speed mode

Explain recursion, What is recursion? Recursion: - Recursion is describ...

What is recursion? Recursion: - Recursion is described as a technique of defining a set or a process in terms of itself.

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