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

What are the type of internet connection, What are the type of Internet con...

What are the type of Internet connection When determining requirements for a VPN, carefully estimate the number of systems to be put behind the VPN, the number of concurrent u

Example of pruning, Example of Pruning: As an example, we are assume t...

Example of Pruning: As an example, we are assume that the four choices for player one, there we are looking only two moves ahead 1 for player one and 1 for player two such as

Define bidirectional bus, Define bidirectional bus? A bidirectional bus...

Define bidirectional bus? A bidirectional bus is that which permits the transfer of data either from memory to CPU during a read operation or from CPU to memory during write op

What is assembly, What is assembly Assemblies are the building blocks o...

What is assembly Assemblies are the building blocks of .NET Framework applications; they variety the fundamental unit of deployment, version control, reuse, activation scoping,

How 74147 series ttl can be used as a decimal-to-bcd encoder, Illustrate ho...

Illustrate how 74147 series TTL can be used as a decimal-to-BCD encoder. Ans. Available IC in 74 series is 74147 that is a priority encoder. Such IC has active low inp

What are benefits and advantages of linq, Benefits and benefits of LINQ are...

Benefits and benefits of LINQ are: 1. Makes it simpler to transform data into objects. 2. A common syntax for all data. 3. Strongly typed code. 4. Provider integration.

Explain the storage class auto, Explain The Storage Class auto The Stor...

Explain The Storage Class auto The Storage Class auto : Variables declared within function bodies are automatic by default. Thus, automatic is the most common of the four stora

What are the elements of analysis model, What are the elements of Analysis ...

What are the elements of Analysis model? i. Data Dictionary ii. Entity Relationship Diagram iii. Data Flow Diagram iv. State Transition Diagram v. Control Specifica

User compatibility & appropriateness of inputs and outputs, User Compatibil...

User Compatibility & Appropriateness of Inputs and Outputs User compatibility - this is the degree to which the machine works towards task completion in way that suits the u

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