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 handshaking, Define Handshaking. Handshaking is a method commonl...

Define Handshaking. Handshaking is a method commonly used to accompany ever data item being transfer with the control signal that show the presence of data in the bus. The unit

What is artificial intelligence fuzzy logic, Fuzzy logic is a form of vario...

Fuzzy logic is a form of various-valued logic; it deals with reasoning that is approximate rather than fixed & exact. In contrast with traditional logic theory, where binary sets h

What is the purpose of reserved word using in c#, A keyword that states the...

A keyword that states the types in a particular namespace can be referred to without requiring their full qualified type names. 'using' reserved word always come with namespace

Explain the term thread scheduling, Problem: a) Most RMI and RPC system...

Problem: a) Most RMI and RPC systems expect to be supported by the "Request-Reply Protocol". Describe what "Request-Reply Protocol" is. b) Describe the invocation semantics

what is feram?, Ferroelectric RAM is a random-access memory same in constr...

Ferroelectric RAM is a random-access memory same in construction to DRAM but uses a ferroelectric layer rather of a dielectric layer to achieve non-volatility. FeRAM is one of a gr

Explain fundamental models of inter process communication, Explain the two ...

Explain the two fundamental models of inter process communication. Two kinds of message passing system are given as: (a) Direct Communication : Along with direct communicat

Illustrate the full form of ooa, Illustrate the Full form of OOA OOA vi...

Illustrate the Full form of OOA OOA views the world as objects consist of data structures and events that trigger operations and behaviours, for object behaviour changes. The b

Enumerate the design reusability of vhdl, Enumerate the Design reusability ...

Enumerate the Design reusability of VHDL VHDL.  Functions  and  Procedures  may  be  placed  in  a  package  so  that  they  are  available  to  any design-unit which wishes t

Types of bus - computer architecture, Types of Bus: Synchronous Bus ...

Types of Bus: Synchronous Bus All devices gain timing information from a common clock line. Each of these intervals constitutes a bus cycle at the time duration w

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