M.Sc. (Semester IV) (CBCS) Examination Mar/Apr-2018
Physics (Applied Electronics)
MICROPROCESSORS INTERFACING
Time: 2½ Hours.
Max. Marks: 70
Instructions: Q.1 and Q.2 are compulsory. Solve any three questions from Q.3 to Q.7. Figures to right indicate full marks.
Q.1

Choose the correct option:
08
All the functions of the ports of 8255 are achieved by programming the bits of an internal register called
data bus control
read logic control
control word register
none of these
If A0=1 then the input read cycle is performed from
port A to data bus
port B to data bus
port C to data bus
CWR to data bus
The procedure of algorithm for interfacing ADC contain
ensuring stability of analog input
issuing start of conversion pulse to ADC
reading digital data output of ADC as equivalent digital output
all of the mentioned
In control word format of 8253, if RL1=1, RL0=1 then the operation performed is
read/load least significant byte only
read/load most significant byte only
read/load LSB first and then MSB
read/load MSB first and then LBS
The number of inputs that can be connected at a time to an ADC that is integrated with successive approximation is
4
2
8
16
Which of the following is not a type of DAC
weighted resistor
successive approximation
R-2R Ladder
none of these
In mode 2 of 8253, if N is loaded as the count value, then after cycles, the output becomes low for
1 clock cycle
2 clock cycles
3 clock cycles
4 clock cycles
The sensor RAM acts as 8-byte first-in-first-out RAM in
keyboard mode
strobed input mode
keyboard and strobed input mode
scanned sensor matrix mode
Page 2 of 2
SLR-UR-582

State True or False:
06
In control word register of 8253, if SC1=1 and SC0=1, then the counter 1 is selected.
The scanned keyboard special error mode is programmed using end interrupt/error mode set command. This mode is valid only under the N-key rollover mode.
In mode 2 of 8255, port A is only used in bidirectional.
The PIC 8259 has four ICWs.
IF A1=1 and A0 1 the PORT A is selected from 8255.
The 8085 has five hardware and eight software interrupts.
Q.2

Explain R-2R Ladder type of DAC.
05

Draw and explain the control word format of 8255.
05

Explain the features of 8259.
04
Q.3

Interface 4K x 4 RAM to 8085. Determine its initial and final address.
08

Explain the pulse/rate generation mode of 8253.
06
Q.4

Interface DAC1408 to 8085 through 8255. Write assembly language program to generate a triangle wave.
08

With the help of suitable block diagram explain successive approximation type ADC.
06
Q.5

Draw and Explain the block diagram of 8279.
08

Explain the hardware interrupts of 8085.
06
Q.6

Interface the 8255 to 8085 in I/O mapped I/O. Consider the address of PORT A=40H. Describe the address decoding logic used for chip selection.
08

Draw the block diagram of PIC8259.
06
Q.7

Interface 8253 to 8085. What are the different operating modes of 8253, explain any one.
08

Explain the different operating modes of 8279.
06