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

Explain the matlab working environment, This is the set of tools and facili...

This is the set of tools and facilities that you work with as the MATLAB user or programmer. It contains facilities for managing the variables in your workspace and importing and e

What are the advantages of hierarchical networks, What are the advantages o...

What are the advantages of Hierarchical Networks? Hierarchical networks are able of handling heavy traffic where needed, and at similar time use minimal number of trunk groups

Give the difference b/w multiprogramming and multiprocessing, Give the diff...

Give the difference between multiprogramming and multiprocessing. A multiprocessing system is a computer hardware configuration which contains more than one independent proc

Why schottky transistors preferred over other transistors , In digital ICs,...

In digital ICs, Schottky transistors are preferred over normal transistors because of their ? Ans. Lower  propagation  delay  in digital ICs, as  shottky  transistors  reduce

Arrays of any size, Modify your program so that the line "int numStones = u...

Modify your program so that the line "int numStones = ui.readStones();" in the Game constructor is considered. Depending on the value of numStones read from the user, you should cr

Determine the binary equivalent of hexadecimal FA, The binary equivalent of...

The binary equivalent of (FA) 16   is ? Ans. (FA) 16 = (11111010) 10

State any three properties of the neutrons, Q. State any three properties o...

Q. State any three properties of the neutrons. (i) A Neutrons are the constituent particles of all nuclei except hydrogen. (ii) As they are neutral particles they aren't de

What is interrupt vector table, Interrupt vector table is always created in...

Interrupt vector table is always created in first 1K area of the memory. Explain why? When CPU receives an interrupt type number from PIC, it uses this number to look up corres

Engineering maths, calculate dy/dx if y=[x-cos(1/cos(xe/2x))]/x

calculate dy/dx if y=[x-cos(1/cos(xe/2x))]/x

Define password methods and biometric systems, Define the password methods ...

Define the password methods and Biometric systems for implementing client server network security. In cyberspace, buyers and sellers cannot notice each other. Also within video

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