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

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


(Electrical & Electronic Engineering)


1. Explain string manipulation instructions of 8086 examples?


2. (a) Write short notes on Assembler?

(b) Write an assembly language program to arrange a list of numbers in ascending order (with out using the assembler)?


3. Interface 8255 with 8086 to work as an I/O port. Initialise Port A as output port,

Port B as input port and port C as output port. Port A address should be 0740H. Write a program to sense switch positions SW0-SW7 connected to port B. The sensed pattern is to be displayed on port A to which 8 LEDs are connected, while PORT C Lower half displays number of on switches out of the total 8 switches.


4. Interface DMA controller 8257 with 8086 so that the channel 0 DMA address register has an I/O address 80 H and the mode set register has an address 88H. Initialize

8257 with a normal priority, TC stop and non extended write. Autoload is not required . Write an ALP to move 2 KB of data from a peripheral device to memory address 2000:5000H with the above initialization.


5. (a) Write an 8086 instruction sequence for transmitting the characters using 8251

on a polled basis.

(b) Write an 8086 instruction sequence for receiving 100 characters using 8251 on a polled basis and store them in memory at location 2050H.


6. (a) Give the features of 8051 microctroller.

(b) Explain the following pins of 8051.

i. AD0 – AD7

ii. T0 and T1

iii. INT0 and INT1

iv. TxD and RxD


7. (a) Write 8051 program as an example of interrupt call to a routine, timer 0 is

used in mode 0 to overflow and set the timer 0 interrupt flag. When the interrupt is generated, the program vectors to the interrupt routine, resets the timer 0 interrupt flag, stops the timer, and returns.

(b) Discuss the bit format of IP register of 8051?


8. (a) Explain with a neat diagram how push button and LED can be connected to 8051

(b) Mention any application of electromagnetic relay and explain how a electromagnetic Relay is connected to a 8051 microcontroller with diagram.

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