JNTU previous year question papers B-Tech III Sem -Microprocessors and interfacing – Aug/Sep 2008

JNTU III B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008

Microprocessors and interfacing

( Common to Electronics & Communication Engineering, Electronics &

Instrumentation Engineering, Bio-Medical Engineering, Electronics &

Control Engineering and Electronics & Telematics)


1. (a) Compare the Interrupt structure of 8086 and 8085 Microprocessors. Also discuss about priorities of the interrupts in both the cases.

(b) With examples ,explain how multiplexing is implemented in 8086 Microprocessor


2. (a) Explain the following 8086 instructions with examples.

i. MUL

ii. IMUL

iii. DIV

iv. IDIV

(b) Differentiate between procedures and macros using certain examples.


3. (a) Write an ALP in 8086 to move a block of N bytes of data from source to destination

(b) Write an ALP in 8086 to add 5 bytes of data in an array by making use of procedure


4. (a) With a neat block diagram, explain the working of 8257 DMA controller

(b) Explain briefly about memory interfacing with 8086 microprocessor


5. (a) Describe the three modes of operations for 8255 using relevant diagrams?

(b) Write the necessary instruction sequence to initialize 8255 with address 0C00H to 0C03H for the following combinations?

(c) Port A as input and ports B and C as output in mode 0 operation.

(d) Port A in mode 1 operation and port B in mode 0 operation.


6. (a) What is the difference between maskable and non-maskable interrupts. Give some examples?

(b) Discuss about the following control word formats of 8259:

i. Initialization Command Words (ICWs).

ii. Operational Command Words (OCWs)


7. (a) Discuss the serial data transmission standards and their specifications.

(b) Draw the block diagram of 8251 and explain about each block.


8. (a) Interface 8255 I/O ports with 8051. The address of port A should be 0000H

(b) Explain about the three errors in asynchronous serial transmission.

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