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 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

Working on dreamweaver, Write your text, format text, insert picture throug...

Write your text, format text, insert picture through Object window or INSERT -> IMAGE. Insert Menu provides you all features which are available under the Object window. Modify men

Explain extended binary coded decimal interchange code, Q. Explain Extended...

Q. Explain Extended Binary Coded Decimal Interchange Code? Extended Binary Coded Decimal Interchange Code (EBCDIC) is a character-encoding format employed by IBM mainframes. It

Explain about double error detection bit, Q. Explain about Double Error Det...

Q. Explain about Double Error Detection bit? Let's presume now that two bit errors take place in data. Data received: So on -matching we conclude P3-D3 pair doesn't

How many bits are required for a ladder d/a converter, How many bits are re...

How many bits are required at the input of a ladder D/A converter, if it is required to give a resolution of 5mV and if the full scale output is +5V. Find the %age resolution.

Explain cocomo model, A COCOMO model is :- COCOMO:- Constructive Cost Es...

A COCOMO model is :- COCOMO:- Constructive Cost Estimation Model.

Explain about physical model, Explain about Physical model The Physical...

Explain about Physical model The Physical model describes concrete software and hardware components of system's context or implementation.

How a typical dma controller can be interfaced to an 8086, Demonstrate how ...

Demonstrate how a typical DMA controller can be interfaced to an 8086/8085 based maximum mode system.  For 8088 in maximum mode: The RQ/GT0 and RQ/GT1 pins are used to is

Explain about zip drive, Q. Explain about Zip Drive? Zip Drive: Loads...

Q. Explain about Zip Drive? Zip Drive: Loads of files, Volumes of data have definitely increased onus on today's computer user and protection of this data is what bugs every

What do you mean by analysis and design, Analysis: Basically, it is the...

Analysis: Basically, it is the process of determining what requirement to be done before how it should be done. In order to accomplish this, the developer shows the existing sy

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