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

We cannot use append structures why, If a table that is to be extended cont...

If a table that is to be extended contains a long field, we cannot use append structures why? Long fields in a table must always be located in the last, as the last field of th

Software interface, what is software interface #Minimum 100 words accepted...

what is software interface #Minimum 100 words accepted#

Explain simple interfacing, Q. Explain Simple Interfacing? The followin...

Q. Explain Simple Interfacing? The following is a sample of the coding, used for procedure interfacing: PUBLIC CUROFF             _TEXT SEGMENT WORD PUBLIC 'CODE'

Explain the application of e-commerce in home banking, Explain the applicat...

Explain the application of E-Commerce in Home Banking. Home Banking: E-commerce is employed in Home Banking like one call or one click. Internet banking or online bank

What is Video Card Interfaces, Q. What is Video Card Interfaces? A video i...

Q. What is Video Card Interfaces? A video interface is the link of video system to rest of the PC. To improve video performance there is required to be an intimate connection betw

How would you implement inheritance using vb.net/c#, How would you implemen...

How would you implement inheritance using VB.NET/C#? When we set out to execute a class using inheritance, we must first start with an existing class from which we will derive

Speed of memory versus speed of CPU, In the past there was a large gap betw...

In the past there was a large gap between speed of a memory andprocessor. So a subroutine execution for an instruction for illustration floating point addition may have to follow a

Discuss the csma/cd and csma/ca protocols, Discuss the CSMA/CD and CSMA/CA ...

Discuss the CSMA/CD and CSMA/CA protocols. CSMA/CD: this is an access method used mainly with LANs configured in a bus topology. Along with CSMA/CD, any station (node) can se

What are qualified associations, What are qualified associations? A qua...

What are qualified associations? A qualified association is an association in which an attribute known as the qualifier disambiguates the object many associated end.

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