Microprocessor Applications And Systems Question Paper

Microprocessor Applications And Systems

Course:Bachelor Of Science

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2009/2010
FIRST SEMESTER EXAMINATION FOR THE DEGREE
BACHELOR OF SCIENCE OF BACHELOR OF EDUCATION

SPH 441: MICROPROCESSOR APPLICATIONS AND SYSTEMS

DATE:
Thursday 24th December, 2009

TIME: 4.30 p.m – 6.30 p.m
------------------------------------------------------------------------------------------------------------
INSTRUCTIONS:
Answer Question and any other TWO Questions. Question ONE carries 30 marks
while each of the other TWO Questions carries 20 marks. The soft instruction is
appended.
1.
a) State and explain any three steps involved in digital circuit design. [3 marks]

i)
Illustrate digital system design using methodology. [4 marks]

ii)
State and explain two system design strategies.
[2 marks]

b) i)
What is a shift register?

[1mark]

ii)
Present the functional table of programmable registers. [2 marks]

iii)
Explain how a shift register is used in multiplication and division.

[2
marks]

c)
i)
State and explain two types of digital counters.
[ 2 marks]

ii)
State two uses of counters.

[2 marks]

d)
i)
Explain the functions of the following 8085 microprocessor
components.

[3
marks]
I. Program
counter
II.
Stack pointer
III.
Instruction register and decoder

Page 1 of 5

ii)
I.
What
is
a
memory?
[1mark]

II.
State two classification of memories and state one example
of
each
class.
[2
marks]

e)
i)
Sketch a labeled block diagram of a semiconductor temperature

transducer.

[2 marks]

ii)
Calculate the output voltage V
?

BE

of the semiconductor transducer above taking

T=85oC, K= 1.38x10-23 JK-1 and Q = 1.6x 10-19 C. [3
marks]

f)
Differentiate between assembler and complier.

[1mark]
2. a)
i) State
and
explain two types of display technologies in common

use.

[2 marks]

ii)
A digital display with a 150 ? limiting register uses 5V supply.

If its driver has a drop of 0.2 V and a diode drop of 1.3 V,
calculate
the
current
through the display.

[3 marks]
b)
i)
State three ways of classifying D/A converters.
[3 marks]

ii)
Draw a labeled diagram of a 4 bit R-2R ladder network DAC.

[4 marks]

iii)
An 8-bit R-2R converter D A is calibrated over the range 0V to

15 V.

Calculate the output is its input is 28H.

[3marks]
c)
i)
What is the main difference between a sensistor and a thermistor.
ii)
Calculate the resistance of a thermistor at 150 oC if its resistance at
0 oC is 20 K ? and the material of thermistor has a constant of
1200K.
3.
a)
State and explain any two modes of operations of 8255 PPI
.

[2 marks]

b)
Present the control word format of 8255 PPI .

[2 marks]

Page 2 of 5

c)
i)
A microprocessor – based system uses 8255 PPI as its I/O device.

If this system is to be used to read bit pattern at port B and output

the same to port A and port C continuously and endlessly, write an

assembly language program to perform this operation using

appropriate 8085 instruction set mnemonics. Take the first memory

location to be 25 FDH and use a delay constant of 25510 in register

pair D.

[6 marks]

ii)
State the memory address of the last byte of your program in

(i)
above

1 mark]
d)
i)
Hand assemble the following using 8055 instruction set assuming that

the first memory location is 42 DEH.

[6 marks]

START
MVI B, 4FH
MVI
C,
78H

MOV
A,
C

OUT 07H
CALL

SUBROUTINE

MVI A, 8FH

MVI B, 68 H

SUB B

ANI 0F H
STA
2070H

CALL SUBROUTINE
AGAIN:
IN

F2H

CMA

OR A A
JZ
AGAIN

SUBROUTINE LX I, 00 FFH

REP:
DCX
D

MOVA,
E

ORA, D
Page 3 of 5

JNZ REP

RET

ii)
State the address of the following in the hand assembled program.

[2 marks]

I.
SUBROUTINE Label
II.
CMA
instruction

4.
a)
i)
What are addressing modes?
ii)
Differentiate between immediate mode and register mode with

reference to 8085 addressing modes. Write a short instruction in

each case to illustrate the difference between the two modes.

[4 marks]

b)
i)
State and explain three classifications of 8085 instruction set sizes.

Write one example of such instructions in each case. [3 marks]

ii)
Write a program of subtracting two numbers; 32H from 48 H

using 8085 assembly language and display the results in port 03 H.

[3 marks]

c)
Consider the following soft assembly language program of a
microprocessor – based system using 8255 PPI.

MVI

A,
80H

OUT 03H

BACK:
MVI A, 55 H
OUT

00
H
OUT

01
H

OUT

02
H

CALL LOOP
MVI
A,
AAH
OUT
00
H
OUT
01
H

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