This document contains 30 important questions related to the microprocessors course for the sessional/GBTU end semester exam in 2013 at Ashoka Institute of Technology & Management in Varanasi, India. The questions cover topics like the flag register, signals, internal architecture, timing diagrams, addressing modes, evolution, interrupts, and interfacing of the 8085 microprocessor. Example programs are provided to convert between binary and BCD numbers, generate delays, transfer data blocks, and interface with keyboards and displays. Comparisons are made between microprocessors and microcontrollers. Additional questions cover demultiplexing address/data lines, control signal generation, segment registers, and functional blocks of support chips like the 8253/8255. Students are directed

1. ASHOKA INSTITUTE OF TECHNOLOGY & MANAGEMENT, AKTHA, SARNATH,
VARANASI, UTTAR PRADESH
30 IMPORTANT QUESTIONS (SESSIONAL/GBTU END SEMESTER EXAM-2013)
FACULTY NAME: - ER. ANUPAM KUMAR, ECE, ASSISTANT PROFESSOR, AITM
SUBJECT CODE & TITLE: -EEC503 & MICROPROCESSORS
1. Give the format of flag register with suitable diagram. And also explain each flags of
8085 microprocessor.
2. Explain the function of- HOLD, ALE, READY, RESET OUT and SID signals of 8085.
3. Draw and explain internal architecture of 8085 microprocessor.
4. What do you mean by Timing diagram? Describe the memory Write machine cycle with
suitable timing diagram for 8085 microprocessor.
5. What do you mean by Addressing mode? Describe the various addressing modes of 8085
with examples.
6. Briefly describe the evolution of microprocessor (8085).
7. Explain the Memory mapped I/O and I/O mapped I/O method with suitable diagram.
8. Define 8085 interrupts. And also explain its types in your own words.
9. Explain the function of Stack Pointer, Accumulator and HL Register pair of 8085.
10. Interface 16 KBEPROM and 48KB SRAM to 8085 with the help of 8KB EPROM ICs
and 8KB SRAM ICs. Draw the address map and show the address decoding logic.
11. Register B has 65H and the accumulator has 97H. Subtract the contents of register B
from the contents of the accumulator. Also give flag status and display the answer at Port
1.
12. The memory location 2050H holds the data byte F7H. Write instructions to transfer the
data byte to the accumulator using three different opcodes: MOV, LDAX and LDA. Also
give your comments.
13. Write a program to convert an 8-bit binary number into a BCD number. Also give flow
chart for conversion.
14. How an ASCII hex number is converted into its binary equivalent? Give flow chart and
subroutine for it.
15. A. Write a program to generate a delay of 0.4 seconds if the crystal frequency is 5 MHZ.

2. B. Write an assembly language program to generate a delay of 1 msec. Also show the
calculation of time. Assume that the crystal frequency of 8085 is 6MHz.
16. Describe the functional block diagram of 8086 microprocessor.
17. With the help of block diagram, describe 8237 DMA controller.
18. How a keyboard and a seven-segment LED are interfaced with 8085 microprocessor?
Explain.
19. Sixteen bytes of data are stored in memory locations at XX50H to XX5FH. Write a
program to transfer the entire block of data to new memory locations starting at XX70H.
20. Write an 8085 assembly language program to transfer an 8-bit data serially, through
SOD lines.
21. Explain the mode 1 operation of 8253 with the help of timing waveform. What will
happen if a new count is written while counter is running?
22. Interface a 4x4-matrix keyboard to 8085. Show the interfacing diagram and write a
routine to read 10 key strokes and store them into memory.
23. Calculate the address lines required for an 8k-byte memory chip.
24. Calculate the number of memory chips needed to design 8k-byte memory if the
memory chip size is 1024x1. (Ans: 64 memory chips needed)
25. Explain the operation performed by following 8085 instructions. Also name the
machine cycles, in sequence, it would take for the execution
(i) XTHL
(ii) CPE 5000H
(iii) RNZ
26. Compare Microprocessor and Microcontroller.
Answer:
Sl. No
Microprocessor
Microcontroller
1
Microprocessor contains
ALU,general purpose
registers,stack pointer, program
counter, clock timing circuit
and interrupt circuit.
Microcontroller contains the circuitry of
microprocessor and in addition it has
built- in ROM, RAM, I/O devices, timers
and counters.
2
It has many instructions to
move data between memory
and CPU.
It has one or two instructions to move
data between memory and CPU.

3. 3
It has one or two bit handling
instructions.
It has many bit handling instructions.
4
Access times for memory and
I/O devices are more.
Less access times for built-in memory
and I/O devices.
5
Microprocessor based system
requires more hardware.
Microcontroller based system requires
less hardware reducing PCB size and
increasing the reliability.
27. What is multiplexing and what is its advantage? How the address and data lines are
demultiplexed in 8085?
Answer: Multiplexing is transferring different information at different well defined times
through same lines. A group of such lines is called multiplexed bus. The advantage of
multiplexing is that fewer pins are required for microprocessors to communicate with outside
world.The low order address and data lines of 8085 are demultiplexed using an external 8-bit DLatch (74LS373) and the ALE signal of 8085, as shown in fig.
74LS373
8085
ADo – AD7
LATCH
D0 - D7
EN
Fig: Demultiplexing of address and data lines in 8085 processor
ALE
At the beginning of every machine cycle, ALE is asserted high and then low. Also the
low byte of address is given out through ADo -AD7 lines. Since the ALE is connected to
Enable of Latch, when ALE is asserted high and then low the addresses are latched into
the output lines of the latch. Now the lines ADo -AD7 are free for data transfer.
28. Explain the generation of control signal in 8085 microprocessor.
29. Write a note on segment register. How physical address is generated in 8086.
30. Draw the internal block diagram of 8255 and explain each block.
OR,
Write the basic operation of DMA.
OR, Draw and explain the functional block diagram of 8253/8254.

4. FOR ANSWER OF THESE QUESTIONS:
 You refer to all previous question papers which were given by me.
 You refer to List of Programs.
 You need to refer memory interfacing materials.
 You need to refers my Class Notes.
 Thanks