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 home banking, Home Banking: E-commerce is used in Home Banking ...

Home Banking: E-commerce is used in Home Banking as single call or single click. Online banking (Internet banking) is a term used for performing transactions, payments etc. ove

Find 9''s compliment of bcd number using 4-bit binary adder, Design a circu...

Design a circuit for determining the 9's compliment of a BCD number by using 4-bit binary adder and some external logic gates? Compliment of a BCD number 9's co

Define security protocols used for e-commerce applications, Define various ...

Define various security protocols used for e-commerce applications. The e-commerce systems of today are composed of very many components as like: a commerce server, client soft

Explain in brief about the insert operation, INSERT OPERATION The inser...

INSERT OPERATION The insert operation inserts a new value into a set of bits. This is done by first masking bits and then O ring them with required value. For illustration, sup

C program, program to find minimum total number of shelfs

program to find minimum total number of shelfs

What is flag, Flag is a flip-flop used to kept the information about the st...

Flag is a flip-flop used to kept the information about the status of a processor and the status of the instruction implemented most recently A software or hardware mark that si

Factor causing parallel overheads, Performance metrics aren't able to attai...

Performance metrics aren't able to attain a linear curve in comparison to increase in number of processors in parallel computer. The main reason for above situation is presence of

Set up a standard population model structure, Set up a standard population ...

Set up a standard population model structure. The population will begin with 24 people. We do not have actual data to support a birth rate, but we could calculate a reasona

Explain the processor-memory interconnection network (pmin), Processor-Memo...

Processor-Memory Interconnection Network (PMIN): It's a switch which attaches several processors to distinct memory modules. Connecting each processor to every memory module in

What is laser printers, Q. What is Laser Printers? Laser Printers are p...

Q. What is Laser Printers? Laser Printers are page printers. For print quality they also face same addressability issues as DMP/InkJet Printers. Though some other methods are p

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