1.
What are the various
registers in 8085? - Accumulator register, Temporary
register, Instruction register, Stack Pointer, Program Counter are the various
registers in 8085 .
2.
In 8085 name the 16
bit registers? - Stack pointer and Program counter all
have 16 bits.
3.
What are the various
flags used in 8085? - Sign flag, Zero flag, Auxillary flag,
Parity flag, Carry flag.
4.
What is Stack
Pointer? - Stack pointer is a special purpose
16-bit register in the Microprocessor, which holds the address of the top of
the stack.
5.
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.
6.
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.
7.
What happens when HLT
instruction is executed in processor? - The
Micro Processor enters into Halt-State and the buses are tri-stated.
8.
What is meant by a
bus? - A bus is a group of conducting lines
that carriers data, address, & control signals.
9.
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.
10.
Give an example of
one address microprocessor? - 8085 is a one
address microprocessor.
11.
In what way
interrupts are classified in 8085? - In
8085 the interrupts are classified as Hardware and Software interrupts.
12.
What are Hardware
interrupts? - TRAP, RST7.5, RST6.5, RST5.5, INTR.
13.
What are Software
interrupts? - RST0, RST1, RST2, RST3, RST4, RST5,
RST6, RST7.
14.
Which interrupt has
the highest priority? - TRAP has the highest priority.
15.
Name 5 different
addressing modes? - Immediate, Direct, Register,
Register indirect, Implied addressing modes.
16.
How many interrupts
are there in 8085? - There are 12 interrupts in 8085.
17.
What is clock
frequency for 8085? - 3 MHz is the maximum clock frequency
for 8085.
18.
What is the RST for
the TRAP? - RST 4.5 is called as TRAP.
19.
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.
20.
What are input &
output devices? - Keyboards, Floppy disk are the
examples of input devices. Printer, LED / LCD display, CRT Monitor are the
examples of output devices.
21.
Can an RC circuit be
used as clock source for 8085? - Yes,
it can be used, if an accurate clock frequency is not required. Also, the
component cost is low compared to LC or Crystal.
22.
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.
23.
Which interrupt is
not level-sensitive in 8085? - RST 7.5 is a
raising edge-triggering interrupt.
24.
What does Quality
factor mean? - The Quality factor is also defined,
as Q. So it is a number, which reflects the lossness of a circuit. Higher the
Q, the lower are the losses.
25.
What are level-triggering
interrupt? - RST 6.5 & RST 5.5 are
level-triggering interrupts.
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