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

Floating point format, consider the 8 bit floating point format including s...

consider the 8 bit floating point format including support for normalised nimbers and nonnumeric values.it included 3 bits for mantissa and 4 bitys for excess 7 exponent

By which each connected device is assigned a time slot, Using             ...

Using                    each connected device is assigned a time slot whether or not the device has anything to send. (A) WDM                                        (B)  FDM

Define technique of improving priority of process wait queue, is a techniqu...

is a technique of improving the priority of process waiting in Queue for CPU allocation? Ageing is a technique of enhancing the priority of process waiting in Queue for CPU all

what is a persistent cookie in php, A persistent cookie is a cookie which ...

A persistent cookie is a cookie which is keeps in a cookie file permanently on the browser's computer. By default, cookies are formed as temporary cookies which keep only in the br

Explain difference between risc and cisc, RISC-Means Reduced Instruction Se...

RISC-Means Reduced Instruction Set Computer. A RISC system has decreased number of instructions and more significantly it is load store architecture were pipelining can be executed

What are the two types of branch prediction techniques, What are the two ty...

What are the two types of branch prediction techniques available?  The two types of branch prediction methods are  1) Static branch prediction  2) Dynamic branch predicti

Explain the potential role of information technology, Question 1: Descr...

Question 1: Describe the five maturity levels of KM that an organization faces when adopting the Frid's KM framework. Question 2: (a) Describe three major issues that

Determine the quivalence partitioning, Determine the quivalence Partitionin...

Determine the quivalence Partitioning? The division of domain data into dissimilar equivalence data classes is performed using Equivalence Partitioning. It is executed for redu

Explain briefly the function of layers, Explain briefly the function of dif...

Explain briefly the function of different layers which are covered under end to end layer connectivity. Different layer are as follows: 1. Transport Layer:  This is res

Explain about semiconductor memories, Q. Explain about Semiconductor Memori...

Q. Explain about Semiconductor Memories? Originally IC technology was used for constructing processor however soon it was realized that same technology can be used for construc

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