Interview Questions.

Question 1. What Are The Various Registers In 8085?

Answer :

Accumulator register, Temporary register, Instruction sign in, Stack Pointer, Program Counter are the various registers in 8085.

Question 2. What Are The Various Flags Used In 8085?

Answer :

Sign flag, Zero flag, Auxillary flag, Parity flag, Carry flag.

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Question 3. What Is Stack Pointer?

Answer :

Stack pointer is a unique reason 16-bit sign in in the Microprocessor, which holds the deal with of the pinnacle of the stack.

Question 4. What Is Program Counter?

Answer :

Program counter holds the address of both the first byte of the following guidance to be fetched for execution or the deal with of the next byte of a multi byte instruction, which has now not been completely fetched.

In each the instances it gets incremented mechanically separately because the training bytes get fetched. Also Program sign in maintains the cope with of the following training.

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Question five. Which Stack Is Used In 8085?

Answer :

LIFO (Last In First Out) stack is used in 8085.In this type of Stack the ultimate saved information can be retrieved first.

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Question 6. What Happens When Hlt Instruction Is Executed In Processor?

Answer :

The Micro Processor enters into Halt-State and the buses are tri-said.

Question 7. What Is Meant By A Bus?

Answer :

A bus is a collection of engaging in strains that companies information, cope with, & manipulate alerts.

Microprocessor Tutorial PLC/Microcontrollers/Microprocessors Interview Questions
Question 8. What Is Tri-kingdom Logic?

Answer :

Three Logic Levels are used and they're High, Low, High impedance state. The high and occasional are ordinary good judgment stages & high impedance kingdom is electric open circuit situations. Tri-kingdom good judgment has a 3rd line known as enable line.

Question 9. Give An Example Of One Address Microprocessor?

Answer :

8085 is a one cope with microprocessor.

Microprocessor 8086 Interview Questions
Question 10. In What Way Interrupts Are Classified In 8085?

Answer :

In 8085 the interrupts are categorised as Hardware and Software interrupts.

Question eleven. What Are Hardware Interrupts?

Answer :

TRAP, RST7.Five, RST6.5, RST5.Five, INTR.

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Question 12. What Are Software Interrupts?

Answer :

RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7.

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Question thirteen. Which Interrupt Has The Highest Priority?

Answer :

TRAP has the best precedence.

Question 14. Name five Different Addressing Modes?

Answer :

Immediate, Direct, Register, Register indirect, Implied addressing modes.

Question 15. How Many Interrupts Are There In 8085?

Answer :

There are 12 interrupts in 8085.

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Question 16. In 8085 Which Is Called As High Order / Low Order Register?

Answer :

Flag is referred to as as Low order check in & Accumulator is known as as High order Register.

Question 17. What Are Input & Output Devices?

Answer :

Keyboards, Floppy disk are the examples of enter gadgets. Printer, LED / LCD display, CRT Monitor are the examples of output gadgets.

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Question 18. Can An Rc Circuit Be Used As Clock Source For 8085?

Answer :

Yes, it can be used, if an accurate clock frequency is not required. Also, the component fee is low compared to LC or Crystal.

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Question 19. Why Crystal Is A Preferred Clock Source?

Answer :

Because of excessive stability, big Q (Quality Factor) & the frequency that doesn’t waft with growing older. Crystal is used as a clock supply maximum of the times.

Question 20. What Does Quality Factor Mean?

Answer :

The Quality component is also described, as Q. So it's miles a number, which reflects the lossness of a circuit. Higher the Q, the lower are the losses.

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Question 21. What Are Level-triggering Interrupt?

Answer :

RST 6.Five & RST five.5 are degree-triggering interrupts

Question 22. How Can Signals Be Classified For The 8085 Microprocessor?

Answer :

The indicators of the 8085 microprocessor based on their capabilities may be categorized into 7 categories particularly:

Frequency and strength alerts
Address and records buses
The manage bus
Interrupt Signals
Serial Input / Output signals
DMA signals
Reset Signals
Question 23. Mention The Various Functional Blocks Of The 8085 Microprocessor.?

Answer :

The diverse practical blocks of the 8085 microprocessor are:

Registers 
Arithmetic common sense unit 
Address buffer 
Increment / decrement deal with latch 
Interrupt manage 
Serial I/O control 
Timing and manipulate circuitry 
Instructions decoder and device cycle encoder.
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Question 24. Mention The Steps In The Interrupt Driven Mode Of Data Transfer.?

Answer :

The steps accompanied in this kind of transfer are as follows:

The peripheral tool might request for an interrupt.
The request acknowledgement for the transfer is issued at the stop of education execution.
Now the ISS recurring is initialized, The PC has the go back address that is now stored within the stack.
Now records transfer is managed and coordinates by way of the ISS.
Again the Interrupt device is enabled and the above steps are repeated.
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Question 25. Write A Program That Will Store The Contents Of An Accumulator And Flag Register At Locations 2000h And 2001h.?

Answer :

By utilising the Push & Pop commands this system can be written as:

LXISP, 4000H - this step initiates the SP at 4000h.
PUSH PSW - the contents of the accumulator and flag are driven into the stack.
POP B 
MOV A, B
STA 2000H
MOV A, C
STA 2001H
HLT
Question 26. Classify Interrupts On The Basis Of Signals. State Their Differences.?

Answer :

On the premise of level the alerts may be categorized into the subsequent sorts:

Single level interrupts
Multi degree interrupts
The differences among them are as follows:
For unmarried the interrupts are manages thru a single ping while in multi they're controlled with the aid of more than one pins.
For unmarried level interrupts polling is essential whereas for multi stage it isn't necessary.
Single degree interrupts are a good deal slower than multi stage interrupts.
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Question 27. What Are The Two Major Differences Between Intr And Other Interrupts ( Hardware)?

Answer :

The two essential differences among INTR and the alternative hardware interrupts are as follows:

All the hardware interrupts are vectored interrupts however the INTR interrupt isn't always so. An INTR interrupt will always get the cope with of a subroutine from the device ( external ) itself. In the case of other hardware interrupts the interrupts come from the call generated by the processor at a already determined vector place.
In case of the INTR interrupt the go back deal with of an interrupt is in no way stored but within the case of other hardware interrupts the places is stored in the stack.
Microprocessor 8086 Interview Questions
Question 28. Explain Briefly The Trap Input For The 8085.?

Answer :

The TRAP enter is touchy to each edge and level.
The pulse width for this signal need to be in excess compared to the regular noise width.
A second lure will by no means be able to respond for the second time because it calls for the first trap to go through a excessive to low transition.
The pulse widths are wider than normal widths in order to save you unwanted fake triggers.
Question 29. Explain Briefly What Happens When The Intr Signal Goes High In The 8085?

Answer :

The INTR is a maskable interrupt for the 8085. It has the lowest precedence and is also non vectored. When this INTR sign goes into the high country the following things occur / take area:

For every preparation this is carried out the 8085 assessments the repute of this interrupt./
Till an education is finished the sign of INTR will remain high. Once an guidance is finished the processor sends an acknowledgement signal INTA.
As soon because the INTA signal is going low a new opcode is positioned on the statistics bus for transfer.
Once the brand new education is acquired the processor saves the cope with of new instruction into the STACK and an interrupt provider subroutine starts.
Question 30. Explain All The Addressing Modes Of The 8085 With The Help Of Examples.?

Answer :

The numerous varieties of addressing modes of the 8085 are as follows:

Direct addressing: The commands in itself comprise the opearand. For ex. STA5513H or in/out commands including IN PORT C.
Register addressing: The standard purpose registers contain the operands. For ex. MOV A, B;
Register oblique addressing: This includes the usage of check in pairs in preference to a single sign up. For ex MOV A, M; ADD M.
Immediate addressing: The instance are MVI A, 07; or ADI 0F and many others.
Implicit addressing: this form of addressing consists of no operands. For ex. RAR, CMA and many others.
Question 31. Mention The Different Types Of Data Transfers Possible In The 8085.?

Answer :

The various forms of statistics transfer operations viable are:

Data switch is feasible among  registers.
It is also feasible among a memory area and a sign in.
Also it can arise among an input/output device and an accumulator.
In truth data is by no means transferred it is able to handiest be copied from one area to every other.
Question 32. What Differences Can You State Between The Hlt And Hold States?

Answer :

The Hold is a hardware input whereas HLT is a software program instruction.
When the HLT kingdom is finished the processor honestly stops and the buses are pushed to tri country. No shape of acknowledgement signal is given out by means of the processor.
In case of HOLD the processor is going into keep state however the buses are not pushed to tri kingdom.
When the processor goes into the HOLD state it offers out an HLDA sign. This signal can be made to use with the aid of different devices.
Question 33. Does The 8085 Support Externally Initiated Operations? If Yes How?

Answer :

Yes the 8085 does support numerous externally initiated operations. The viable operations and the corresponding pins for them within the 8085 are as follows:

It helps resetting ( this is feasible with the Reset Pin ).
Various interruptions ( those are viable through Trap, RST 7.Five, 6.Five, 5.Five and the interrupt pins. )
The 8085 additionally helps Readying with the assist pf the Ready pin.
It also has a HOLD pin that may essentially pause the operation until required/ as required.
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Question 34. Explain The Flow Of A Typical Instruction Word.?

Answer :

The waft of a regular Instruction phrase is as follows:

The content material of the program counter of 2 byte is transferred to the deal with register known as MAR ( memory deal with sign up ). This takes place at the beginning of a fetch cycle.
The contents are transferred through the cope with bus.
Once that is completed the timing and manage section of the processor reads the contents of the referenced reminiscence address place.
After this the facts is sent to the memory information sign up with the assist of the facts bus.
Now the facts is located in the education sign up with a view to ultimately decode and execute it.
Question 35. Briefly Explain The Steps Involved In A Fetch Cycle.?

Answer :

Fetch cycle is the time required to fetch an opcode from a specific region in reminiscence.

General Fetch Cycles encompass 3T states.
The first T state entails the sending of the memory address stored inside the Program Counter to the reminiscence.
During the second one T state the contents of the addressed reminiscence is read ( this commonly is the opcode at the required location)
In the 0.33 T country the opcode is despatched to the Instruction sign up via the information bus for execution.
For slower recollections the processors has the supply to get in to the WAIT cycles as well.
Question 36. What Are Wait States In Microprocessors, Explain.?

Answer :

The WAIT state plays a good sized role in preventing CPU pace incompatibilities.
Many a times the processor is at a ready nation to simply accept facts from a tool or vicinity, but there is probably no input available. This can result in wastage of cpu time.
So in such instances when the cpu is ready for an enter however there is no such valid statistics then the device gets into WAIT country. In this scenario the pin 35 ( ready pin )is put right into a low country.
As soon as there's a few legitimate data for the 8085 the system comes off the WAIT state and the low state of the READY pin is withdrawn.
8051 Microcontroller Interview Questions
Question 37. What Are The Boons And Banes Of Having More General Purpose Registers In A Microprocessor.?

Answer :

If there are greater popular cause registers this system writing technique is more flexible and convenient.
The number of bits that might be required to hit upon the registers could growth with extra registers, this effects within the decreasing of the wide variety of operations.
When a program might contain CALL subroutines the popularity of the registers might need to be stored and restored frequently, this will bring about a tremendous overhead for the processor.
Higher the quantity of these registers mores area would be used by them on the chip. This can create troubles in including / imposing different capabilities at the chip.
Question 38. Explain In Brief The Control And Timing Circuitry Of The 8085.?

Answer :

The timing and manipulate circuitry segment of the 8085 is liable for the era of timing and manipulate indicators in order that commands can be completed.
The forms of indicators involved are : Clock indicators, Control signals, Status alerts, DMA alerts and also the reset segment.
It is answerable for the fetching and the decoding of the numerous operations.
This phase also aids within the generations of manipulate alerts for the executions of instructions and for the sync among outside gadgets.
Question 39. Explain Briefly The Flag Register In The 8085 Microprocessor.?

Answer :

The flag check in in 8085 is an 8-bit sign in which includes five bit positions.
These 5 flags are of 1bit F/F and are known as zero, signal, carry, parity and auxiliary deliver.
For signal flag if the result of an MSB operation is 1 then it's miles set else it's far reset.
The 0 flag is ready of the end result of an preparation is 0.
The auxiliary convey flag is used for BCD operations, not loose to the programmer.
The bring flag is used for wearing and borrowing in case of addition and subtraction operations.
The parity flag is used for results containing an excellent quantity of 1's.
Question forty. What Is A Stack Pointer Register, Describe Briefly.?

Answer :

The Stack pointer is a 16 bit sign up used to factor at the stack.
In read write memory the places at which transient statistics and return addresses are stored is referred to as the stack.
In easy phrases stack acts like an auto decrement facility within the machine.
The initialization of the stack pinnacle is performed with the help of an guidance LXI SP.
In order to avoid software crashes a software must usually be written at one stop and initialized at the opposite.
Advanced C++ Interview Questions
Question forty one. Describe Briefly The Accumulator Register Of 8085.?

Answer :

It is one of the maximum essential 8 bit register of 8085
It is accountable for coordinating enter and output to and from the microprocessor thru it.
The primary reason of this sign up is to shop temporary statistics and for the position of very last values of arithmetic and logical operations.
This accumulator register is in particular used for arithmetic, logical, keep and rotate operations.