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

Define the system users, Q. Define the System users? System users are d...

Q. Define the System users? System users are defined as the people who employ information systems or who are affected by information system on a regular basis i.e. validating,

Explain about interrupt-processing sequence, Q. Explain about Interrupt-Pro...

Q. Explain about Interrupt-Processing Sequence? The occurrence of an interrupt fires a numbers of events both in processor hardware and software. Figure below displays a sequen

Why does dma have priority over the cpu, Why does DMA have priority over th...

Why does DMA have priority over the CPU when both request a memory transfer? The data transfer monitored by DMA controller which is called as DMA channel. The CPU is included o

What is the system call available to transmit a signal, What is the system ...

What is the system call available to transmit a signal? System call Kill is used to send a signal to a method or a group of processes. Int kill (pad tepid, Int sig); This

Superscalar processors, Superscalar Processors In scalar processors, on...

Superscalar Processors In scalar processors, only one instruction is implemented per cycle. That means only single instruction is issued per cycle and only single instruction i

Compare the cocomo model with the detailed cocomo model, Compare the basic ...

Compare the basic COCOMO model with the detailed COCOMO model. COCOMO having of a hierarchy of three increasingly detailed and accurate forms. -  Basic COCOMO - is a stati

Hyper-threading, Hyper-threading, officially known as Hyper-threading Techn...

Hyper-threading, officially known as Hyper-threading Technology (HTT), is Intel's trademark for their execution of the simultaneous multithreading technology on the Pentium 4 micro

What is associative search, What is associative search? The cost of an ...

What is associative search? The cost of an associative cache is higher that the cost of a direct mapped cache due to the need to search all 128 bit tag patterns to verify wheth

Application and function areas - artificial intelligence, Application and F...

Application and Function Areas - artificial intelligence: Individual applications and function often drive "AI" research much more than the long term relative field described

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