Hardware Interrupt:-
As i have already discussed that there are 6 interrupt pins in the microprocessor used as Hardware Interrrupts given below:
TRAP
RST7.5
RST6.5
RST5.5
INTR
INTA is not an interrupt. INTA is used by the Microprocessor for sending
 the acknowledgement. TRAP has highest priority and RST7.5 has second highest priority and so on.
The Vector address of these interrupts are given below:
                                          
1.TRAP:-It is non maskable edge and level triggered interrupt. TRAP has the highest priority and vectores interrupt. Edge and level triggered means that the TRAP must go high and remain high until it is acknowledged. In case of sudden power failure, it executes a ISR and send the data from main memory to backup memory.
As we know that TRAP can not be masked but it can be delayed using HOLD signal.
This interrupt transfers the microprocessor's control to location 0024H.
How a TRAP interrupt may be masked???
TRAP interrupts can only be masked by reseting the microprocessor. There is no other way to mask it.

2.RST7.5:-It has the second highest priority. It is maskable and edge level triggered interrupt. The vector address of this interrupt is 003CH. Edge sensitive means input goes high and no need to maintain high state until it is recognized.
How It may be masked??
It can also be reset or masked by reseting microprocessor. It can also be resetted by DI instruction.

3.RST6.5 and RST5.5:-These are level triggered and maskable interrupts. When RST6.5 pin is at logic 1, INTE flip-flop is set. RST 6.5 has third highest priority and RST 5.5 has fourth highest priority.
It can be masked by giving DI and SIM instructions or by reseting microprocessor.



4.INTR:-It is level triggered and maskable interrupt. It has the lowest priority. It can be disabled by reseting the microprocessor or by DI and SIM instruction.


The following sequence of events occurs when INTR signal goes high:
1. The 8085 checks the status of INTR signal during execution of each instruction.

2. If INTR signal is high, then 8085 complete its current instruction and sends active low interrupt acknowledge signal, if the interrupt is enabled.

3.On receiving the instruction, the 8085 save the address of next instruction on stack and execute received instruction.









{ 30 comments... read them below or Comment }

  1. what is the vector add. for intr

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    Replies
    1. there is no fix address of intr ....there are fix address only for trap,rst 7.5,rst 6.5 nd rst 5.5.......
      if u want the intr vector address then mp sends an inta means interrupt acknoledgement to external hardware ...

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    2. INTR is a non vectored interrupt so it has no vectored address -_-

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    3. there is no vector address for INTR

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  2. the essential difference between traps and interupts is
    1) traps are synchronous and interrupts are asynchronous with the program.
    2) traps are asynchronous and interrupts are synchronous with the program.
    3) traps are synchronous and interrupts are asynchronous with the I/O devices.
    4) none of these.

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    Replies
    1. TRAP is also a Interrupt known as Hard ware Interrupt.so u can't differentiate b/w Trap & interrupt.

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  3. Is software interrupts are having highest priority or hardware interrupts.........?

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    Replies
    1. Hardware interrupts have higher priority than software interrupts.

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    2. Hardware interrupts have higher priority than software interrupts.

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  4. Is software interrupts are having highest priority or hardware interrupts.........?

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  5. what is the vector address for INTR??

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  6. INTR is non-vectored. It does not have a vector address

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  7. INTR is non-vectored. It does not have a vector address

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  8. why the names of the interrupts are RST 5.5, RST 6.5, RST 7.5? Why isn't it RST 1.5, RST 2.5 and so on. I'm concerned with the numbering.

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  9. what is vector address of RST 6.5 and 5.5??? :\

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    Replies
    1. This comment has been removed by the author.

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    2. for-6.5-
      6.5 x 8= 52
      52/16=quo-3 rem-4

      vectr addr- 0034
      i.e format is- 00

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  10. All this copied word to word from here - http://scanftree.com/microprocessor/Interrupts-In-8085

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  11. We know already INTR is not a Intrupt so has no vector address.only Intrupts(INTA,RST7.5 ,RST6.5,RST5.5) has vector address.

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  12. Dear Aman your answer is here
    To find vector address of any Intrupts have to do the following steps.
    Firs multiply intrupt with 8 and if the result is less than 16 we have to divide the resulted value by 8
    And if the result is greater than 16 we have to divide the resulted value by 16 .
    To find vector address of Intrupts 6.5
    Intrup number ×8
    6.5 ×8=44.0= 44
    Since 44 is greater than 15 therefore we have to divide 44 by 16 and we find
    16|44|2
    32
    -
    12
    We know that c= 12
    Therefore vector addres is 002CH(vector address of Intrupt6.5)
    H represents Hexa

    ReplyDelete
  13. Dear Aman your answer is here
    To find vector address of any Intrupts have to do the following steps.
    Firs multiply intrupt with 8 and if the result is less than 16 we have to divide the resulted value by 8
    And if the result is greater than 16 we have to divide the resulted value by 16 .
    To find vector address of Intrupts 6.5
    Intrup number ×8
    6.5 ×8=44.0= 44
    Since 44 is greater than 15 therefore we have to divide 44 by 16 and we find
    16|44|2
    32
    -
    12
    We know that c= 12
    Therefore vector addres is 002CH(vector address of Intrupt6.5)
    H represents Hexa

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  14. We know already INTR is not a Intrupt so has no vector address.only Intrupts(INTA,RST7.5 ,RST6.5,RST5.5) has vector address.

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  15. We know already INTR is not a Intrupt so has no vector address.only Intrupts(INTA,RST7.5 ,RST6.5,RST5.5) has vector address.

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  16. We know already INTR is not a Intrupt so has no vector address.only Intrupts(INTA,RST7.5 ,RST6.5,RST5.5) has vector address.

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  17. 1. What is the highest priority?
    Trap or RST 6.5
    Hold priority is higher than trap priority. Is it correct or not ?

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  18. This comment has been removed by the author.

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  19. There is one software pin in 8085 m p.what is name of that pin

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