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

The six various application of stack, The six several application of stack ...

The six several application of stack in computer application is: 1.  Conversion of infix to postfix notation and vice versa. 2.  Evaluation of arithmetic expression. 3.

Software engineering, specialization,ggeneralization and aggregation of rai...

specialization,ggeneralization and aggregation of railway reservation system?

Automatic typewriter in information distribution, Automatic typewriter : I...

Automatic typewriter : It is a power-driven machine, which automatically types a standard pro forma from a previously punched or stencilled master. When the master is placed on th

What are cosmic rays, Q. What are cosmic rays? The ionising radiation s...

Q. What are cosmic rays? The ionising radiation several times stronger than γ-rays entering the earth from all the directions from cosmic or interstellar space is known as cosm

Calculate the propagation delay for output, Problem: (a) Consider the ...

Problem: (a) Consider the following combinational circuit: (i) Calculate the propagation delay for each output. Assume each gate has a delay of 10 ns. (ii) The abo

Direct addressing and immediate addressing mode , Direct Addressing and  I...

Direct Addressing and  Immediate Addressing mode - computer architecture:  Immediate Addressing: It is the simplest form of addressing. Here, the operand is itself given

Explain naming convention libraries, Explanation:- Common used functions...

Explanation:- Common used functions are placed in libraries. These are located in the SQABas32 subdirectory of the Robot working directory. A library is separated into three fil

Specifying optimisation criteria of describe function, Specifying Optimisat...

Specifying Optimisation Criteria Specify values to be minimized, maximized or optimized. You can understand it as way you normalize data in database. For instance, you should

Principles of logic circuits, A logic gate is an electronic circuit that ge...

A logic gate is an electronic circuit that generates a typical output signal which depends on its input signal. Output signal of a gate is a general boolean operation of its input

The voltage of telephone given by telephone companies, Telephone companies ...

Telephone companies normally provide a voltage of to power telephones? Telephone companies usually give a voltage of to power telephones -48 volts DC.

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