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 do you mean by daisy chain, Q. What do you mean by Daisy chain? Th...

Q. What do you mean by Daisy chain? This scheme provides a hardware poll. With this scheme, an interrupt acknowledge line is chain by different interrupt devices. All I/O inter

What is the relation between response time and throughput, The Throughput g...

The Throughput graph represents the amount of data in bytes that the Vusers received from the server in a second. When we evaluate this with the transaction response time, we will

Subsequent statements set every element of matrix, Q. Subsequent statements...

Q. Subsequent statements set every element of matrix? Let a= [2,4,6,8,10], b=[1,3,5,7,9], c=[0,0,0,0,0] Consider the subsequent program section FORALL (i = 2:4)   a(i)

Application area of artificial intelligence, 1. The State of the Art: What ...

1. The State of the Art: What can AI do today? A concise answer is difficult because there are so many activities in so many subfields. Here we sample a few applications other

Explain technical reasons which made microsoft withdraw, Explain technical ...

Explain technical reasons which made Microsoft withdraw its support for VBA in Mac? Ans) The reasons which made Microsoft drop its carry to VBA are as follows, Microsoft visual

Reflexes - artificial intelligence, Reflexes - artificial intelligence: ...

Reflexes - artificial intelligence: If an agent decides upon and executes an action in response to a sensor input without consultation of its world, then this can be considere

Simulate a real life product development , The goal is to simulate a real l...

The goal is to simulate a real life product development and familiarize learners with the design process of a system, component, or process to meet desired requires within realisti

Which header file is used for screen handling function, Which header file i...

Which header file is used for screen handling function:- The header files stdio.h having definitions of constants, macros and types, along with function declarations for stan

What is verilog, What is Verilog Verilog  language  is  still  rooted  ...

What is Verilog Verilog  language  is  still  rooted  in  it's  native  interpretative  mode.  Compilation  is  a means of speeding up simulation however has not changed the or

Convert the decimal number to excess-3 code, Convert the decimal number 430...

Convert the decimal number 430 to Excess-3 code ? Ans. Excess  3  is  a  digital  code  acquired  from  adding  3  to  every  decimal  digit  and  after that converting the res

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