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

Ethernet 10 base 2 is an example of which topology, Ethernet 10 Base 2 is a...

Ethernet 10 Base 2 is an example of               network topology. (A)  Bus                                           (B)  Ring (C)  Star

Smtp vs esmtp, what shortcomings of smtp are over come by esmtp?

what shortcomings of smtp are over come by esmtp?

What are the different types of parameters, What are the different types of...

What are the different types of parameters? Formal Parameters: Parameters, which are described during the definition of subroutine with the FORM statement.

Explain about server synchronization, Q. Explain about Server synchronizati...

Q. Explain about Server synchronization? Server synchronization: It updates atom by server process of requesting process. In this method an atom acts as a unique update server.

Failures, FAILURES Since reliability engineering is focused on the surv...

FAILURES Since reliability engineering is focused on the survivability or absence of failures, it is more concerned about failures,  understanding  their causes and defining re

Calculate traffic lost in a particular exchange, In a particular exchange d...

In a particular exchange during busy hour 1200 calls were offered to a group of trunks, during this time 6 calls were lost. The average call duration being 3 minutes Calculate Tr

Define router, A router is used to Distributes information among networ...

A router is used to Distributes information among networks.

Memory cache hierarchy and virtual memory system, 1. Detail for each of the...

1. Detail for each of the four following MIPS instructions, which actions are being taken at each of their five steps. Do not forget to mention how and during which steps each inst

What is the function of cu, What is the function of CU? The control uni...

What is the function of CU? The control unit works as the nerve center that coordinates all the computer operations. It issues timing signals that governs the data transfer.

Serial execution and parallel execution, Serial Execution Execution of ...

Serial Execution Execution of a program consecutively, one statement at a time. In the easiest sense, this is what occurs on a one processor machine. However, even many of the

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