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 memory transfer process, Q. Explain the Memory Transfer process...

Q. Explain the Memory Transfer process? Memory Transfer Transfer of information from memory to outside world which implies I/O Interface is known as a read operation. Tra

Define miss penalty, Define miss penalty? The extra time required to br...

Define miss penalty? The extra time required to bring the desired information into the cache is known as miss penalty.

When can a user program execution be interrupted, When can a user program e...

When can a user program execution be interrupted? It won't be desirable to interrupt a program when an instruction is being executed and is in a state such as instruction decod

Software engineering, #quest2. Each time a defect gets detected and fixed, ...

#quest2. Each time a defect gets detected and fixed, the reliability of a software production..

Show basic concepts of permutation, Q. Show Basic concepts of permutation? ...

Q. Show Basic concepts of permutation? Let us look at the basic concepts of permutation with respect to interconnection network.  Let us say the network has set of n input node

Prolog programming language, Prolog Programming Language : Probably pr...

Prolog Programming Language : Probably programming languages are procedural: than the programmer specifies exactly the right instructions (algorithms) required to get an agent

Illustrate about compact disk rewritable, Q. Illustrate about Compact Disk ...

Q. Illustrate about Compact Disk Rewritable? CD-RW optical disk can be repeatedly written and overwritten same as with a magnetic disk. Even though a number of techniques have

C++, A palindrome is a string that reads the same from both the ends. Given...

A palindrome is a string that reads the same from both the ends. Given a string S convert it to a palindrome by doing character replacement. Your task is to convert S to palindrome

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