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

Advantages to companies adopting call centres, Advantages to companies adop...

Advantages to companies adopting call centres Computer systems have allowed companies to set up call centres in other nations where potential cost savings can be made. This, of

Explain language processor development tools by diagram, Explain Language ...

Explain Language Processor Development Tools (LPDTs) through schematic diagram. LPDT that is Language processor development tools focuses upon generation of the analysis phase

What is turnaround time, What is turnaround time? Turnaround time is th...

What is turnaround time? Turnaround time is the interval from the time of submission to the time of completion of a process. It is the sum of the periods spent waiting to get i

Prolog programming language - artificial intelligence, Prolog Programming L...

Prolog Programming Language - Artificial intelligence: Most of the programming languages are procedural: the programmer specifies exactly the correct instructions (algorithms)

Effectiveness - efficiency - safety and utility of site, Based on your unde...

Based on your understanding of Unit 2, compile a set of five usability and/or user experience goals which you think will be useful in evaluating the two sites when gathering the in

What are the registers generally contained in the processor, What are the r...

What are the registers generally contained in the processor? MAR-memory address register MDR-memory data register IR-Instruction Register RO-Rn-General purpose registe

Explain what logic gets synthesized , What logic gets synthesized when I us...

What logic gets synthesized when I use an integer instead of a reg variable as a storage element? Is use of integer recommended? An  integer  can  take  place  of  a  reg  as

How many types of keys used to encrypt and decrypt data, How many types of ...

How many types of keys used to encrypt and decrypt data in Secure Sockets Layer? Two forms of keys are used as ciphers to decrypt and encrypt data. Private keys are referred to

What are parallel algorithms, What are Parallel Algorithms? The central...

What are Parallel Algorithms? The central assumption of the RAM model does not hold for some newer computers that can implement operations concurrently, i.e., in parallel algor

Display methods, Describe a console application project to show the differe...

Describe a console application project to show the different formatting styles used in display methods(i.e.Console.writeLine()).

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