MicroProcessor interview questions

MicroProcessor

interview

questions

Ø   What is a Microprocessor?

Microprocessor
is a program-controlled device, which fetches the instructions from memory,
decodes and executes the instructions. Most Micro Processor are
single- chip devices.

Ø   What are the flags in 8086?

In
8086 Carry flag, Parity flag, Auxiliary carry flag,
Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign
flag.

Ø   Why crystal is a preferred clock source?

Because
of high stability, large Q (Quality Factor) & the frequency that doesn?t drift with aging. Crystal
is used as a clock source most of the times.

Ø   In 8085 which is called as High order /
Low order Register?

Flag
is called as Low order register & Accumulator is called as High order
Register.

Ø   What is Tri-state logic?

Three
Logic Levels are used and they are High, Low, High impedance state. The high
and low are normal logic levels & high impedance state is electrical open
circuit conditions. Tri-state logic has a third line called enable line.

Ø   What happens when HLT instruction is
executed in processor?

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

Ø   Which Stack is used in 8085?

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

Ø   What is Program counter?

Program
counter holds the address of either the first byte of the next instruction to
be fetched for execution or the address of the next byte of a multi byte
instruction, which has not been completely fetched. In both the cases it gets
incremented automatically one by one as the instruction bytes get fetched. Also
Program register keeps the address of the next instruction.

Ø   What are the various registers in 8085?

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

Ø   What is 1st / 2nd / 3rd / 4th generation
processor?

The
processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd
/ 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.

Ø   Name the processor lines of two major
manufacturers?

High-end:
Intel - Pentium (II, III, 4), AMD - Athlon. Low-end:
Intel - Celeron, AMD - Duron. 64-bit: Intel - Itanium
2, AMD - Opteron.

Ø   What?s the
speed and device maximum specs for Firewire?

IEEE
1394 (Firewire) supports the maximum of 63 connected
devices with speeds up to 400 Mbps. Where?s
MBR located on the disk? Main Boot Record is located in sector 0, track 0, head
0, cylinder 0 of the primary active partition.

Ø   Where does CPU
Enhanced mode originate from?

Intel?s 80386 was the first 32-bit processor, and since
the company had to backward-support the 8086. All the modern Intel-based
processors run in the Enhanced mode, capable of switching between Real mode
(just like the real 8086) and Protected mode, which is
the current mode of operation.

Ø   How many bit combinations are there in a
byte?

Byte
contains 8 combinations of bits.

Ø   Have you studied buses? What types?

There
are three types of buses.

Address
bus: This is used to carry the Address to the memory to fetch either
Instruction or Data.

Data
bus : This is used to carry the Data from the memory.

Control
bus : This is used to carry the Control signals like
RD/WR, Select etc.

Ø   What is the Maximum clock frequency in
8086?

5 Mhz is the Maximum clock frequency
in 8086.

Ø   What is meant by Maskable
interrupts?

An
interrupt that can be turned off by the programmer is known as Maskable interrupt.

Ø   What is Non-Maskable
interrupts?

An
interrupt which can be never be turned off (ie.
disabled) is known as Non-Maskable interrupt

Ø   What are the different functional units
in 8086?

Bus
Interface Unit and Execution unit, are the two different functional units in
8086.

Ø   What are the various segment
registers in 8086?

Code, Data, Stack, Extra Segment registers in
8086.

Ø   What does EU do?

Execution
Unit receives program instruction codes and data from BIU, executes these instructions
and store the result in general registers.

Ø   Which Stack is used in 8086? k is used in 8086?

FIFO
(First In First Out) stack is used in 8086.In this
type of Stack the first stored information is retrieved first.

Ø   What are the flags in 8086?

In
8086 Carry flag, Parity flag, Auxiliary carry flag,
Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign
flag.

Ø   What is SIM and RIM
instructions?

SIM
is Set Interrupt Mask. Used to mask the hardware interrupts.

RIM
is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.

Ø   What is the difference between 8086 and
8088?

The
BIU in 8088 is 8-bit data bus & 16- bit in 8086.Instruction queue is 4 byte
long in 8088and 6 byte in 8086.

Ø   Give example for Non-Maskable
interrupts?

Trap
is known as Non-Maskable interrupts, which is used in
emergency condition.

Ø   Give examples for Micro controller?

Z80,
Intel MSC51 &96, Motorola are the best examples of Microcontroller.

Thank U friends

Urs

Mavvsn Reddy