3-1 B.Tech (CSE)
Microprocessors-II Sample Questions
UNIT – I
1) Describe the various methods of mapping I/O
devices with examples Discuss the relative advantages.
2) What is the significance of interrupt flag in a Microprocessor?
3) What is an assembler directive?
List at least four assembler directives of 8086 μ p.
4) How many address lines are necessary to address two
mega bytes (2048 k) of memory?
5) How are memories classified?
6) Differentiate between RAM, ROM, PROM, DRAM and SRAM.
7) In a microprocessor bits 0 to 10 are connected to various
2K byte-memory are present in the system. Bits 11 and
12 are not used, bits 13, 14, 15 are used for generating
the chip-select for memories. Give the complete interfacing
details and address range for each 2K byte block.
8) Explain how a 8 K*8 SRAM is interfaced to 8085 Microprocessor.
9) An 8085 based kit has the following:
4 k ROM – 2 k x 2 (2716) 2 k RAM - 2k x 1 (6116) The memory
addresses are sequential from 4000H onwards. Design
the complete scheme and specify how the chip select (CS)
signal is obtained. Show the neat diagram of the memory organization.
10) Distinguish between SRAM and DRAM.
11) Explain how 74LS138 decoder is used in interfacing
memory with microprocessor.
12) An 8086 based micro computer in the minimum mode is to be
designed to provide 2K x 16 EPROM and 1K x 16 SRAM and six 8
bit I/O ports. Use 2716 EPROM, 2142 SRAM and 8255 I/O chips.
Use suitable decoding circuits and give a neat detailed diagram
showing important signal connections and memory map.
13) Give the I/O diagram, Functional block diagram, Function table,
memory cell, and Read Timing diagram for 2K x 8 SRAM.
Explain its working.
14) Design 16k x 8 SRAM memory interfacing at 4000H
using 2k x 8 SRAMS with 8085 based system with fully
decodes addressing logic.Give memory address range for
each SRAM.
15) Give important specifications of a semiconductor memory device.
16) How a bit stored in a FAMOS device can be erased.
17) Distinguish between P interfacing and I/O interfacing.
18) An SRAM has an external organization of 8 K x 8. Internally the
SRAM uses two-level decoding and an optimal memory array
geometry. Draw a block diagram showing the functional blocks that
make up the SRAM‟s internal structure and the external connections
to these blocks. The memory has common I/O, an active low chip
select, CS , an active low write enable, WE , and an active low output
enable, OE . Be sure to include in your diagram input buffers, and
output buffers, and control logic. Also provide the following
information about the SRAM: number of logical words, number of
physical words, number of bits in a logical word, number of bits in a
physical word, and segmentation.
19) A memory system is to be designed that contains 16Kx8 of EPROM
followed by 16K x 8 of RWM. The 16Kx8 of EPROM followed by
16Kx8 of RWM. The 16Kx8 of EPROM starts at address OH and is
implemented using a 27128A EPROM, which is 16Kx8. The
27128A EPROM, which is 16Kx8. The 27128A has two control
inputs, chip enable,CE , and output enable,OE . These devices have
common I/O and control inputs CE , OE and WE . Decoding is to be
exhaustive and accomplished using only a 74ALS138 decoder and a
four-input AND gate. Draw the logic diagram of the memory
system and its interface to the required signals from an 8085A or
8086 system bus.
20) Write the memory cell for PROM and EPROM
UNIT – II
21) Programmable Logic Devices.
22) Half-adder implementation using PLDs
23) What is the advantages of interrupt driven I/O
over the programme I/O?
24) What is the significance of interrupt flag in a Microprocessor?
25) Explain the necessity of interfacing circuits.
What are the variou methods of the I/O devices?
26) Explain the
(i) Polled interrupt scheme of I/O and
(ii) Vectored interrupt scheme of I/O.
27) Explain memory mapped I/O and I/O mapped I/O schemes.
What are their relative merits.
28) Explain what you understand by handshaking in data transfer
operation.
29) Distinguish between memory mapped I/O and I/O mapped I/O.
30) Give example for digital input device, digital
output device anddigital input and output device.
31) What is I/O interfacing ? Is it same as μP, interfacing or not?
Justify your answer with suitable examples. Explain clearly the
general requirements of an interface circuit for commonly used
I/O devices. Describe, in general, certain types of registers
with their functions, that are common to all programmable interface circuits.
32) What do you understand by “Interfacing an I/O device to P.”
Give the characteristics and functions of different types of
interfaces with respect to a P system.
Outline briefly the procedure for interfacing an I/O device to a P based system.
33) Compare and contrast various I/O programming methods.
34) Write an I/O program that reads the DIP switch and if bit i is switched on, cause the corresponding decimal digit i to be displayed by the LED display unit.
UNIT – III
35) Explain mode-1 and mode-2 operations of 8255 PPI with suitable examples.
36) Explain how a set of 8 LEDS can be made ON/OFF
using switches through an interfacing peripheral and
8085 or 8086microprocessor.
37) Write initialization instructions for 8255PPI to set-up in mode „o‟
(i) PORT-A as an input port
(ii) PORT-B as an output port
(iii) PORT-C (low) as an output port and
(iv) PORT-C (high) as an input port.
38) Briefly describe the various modes of operation 8255 PPI.
How is it useful in interfacing I/O devices?
39) An A/D converter output is to be inputted using 8255 port A.
The A/D converter is of 12-bit resolution. Use PC6 for start of
conversion and the end of conversion is connected to STBA.
Use status check for inputting the data. Write an 8086 ALP to
acquire the data and store it in location DATA
40) What are the various modes of operations of 8255 PPI chip?
41) Sketch and explain the block diagram of 8255 PPI.
Explain the operations of mode 0, mode 1 and mode 2 of 8255.
42) An 12-bit ADC is to be interfaced to 8086 through
8255 I/O ports. Give the full interfacing details as
a memory mapped I/O with a simple program to
demonstrate input and output operations.
43) Interface two 8255s with 8051 and write an ALP
to initialize the 8255 chips with all ports or input
ports in mode „0‟. Read all the 8255 ports and store
the data read from 8255 ports in the external RAM
at the addresses starting from D000H.
44) Identify peripheral interface IC you have studied
that has maximum number of μp interface signals.
45) Give Hardware and Software to interface a 4 x 4
Push Button Keyboard matrix to 8086-based system
using 8255 via a single port only.
46) The 8255 PPI is to be used to interface a single seven
segment LED display unit and an 8-bit DIP switch to
an 8085 based system.
47) Draw a logic diagram showing all connections between
the LED, the DIP switch, the 8255, and the system bus.
Show also any additional components needed, such as driver circuits.
48) Assume that two similar P based systems are to be
linked for exchanging messages. Consider a message
as a sequence of maximum 100 data bytes that must be
transferred from the main memory of one system to that
of the other system. Message transfer is accomplished by
each system treating the other as one of its I/O devices.
Using either 8085 or 8086 to complement the host Ps.,
carry out the following:
49) Design a suitable hardware interface for intersystem
communication based on programmable interface
circuits such as the 8255 or 8251.
50) Write the structure of software needed for message
transfer, explaining clearly how the activities of the
two Ps are synchronized.
51) What is the necessity of interrupt controller?
Explain with the help of neat block diagram the
operation of8259 –Interrupt controller interface.
52) What are the different modes of 8253 timer operation?
53) What is meant by “wait state” and when is it used?
54) Explain how do you interface a 8259 PIC to 8086 μp.
Describe dthe differences between a “protected mode”
and “real mode” interrupt.
55) Explain the architecture of 8279 programmable display/keyboard interface chip.
56) Give a neat schematic of 8251 USART and describe its operation.
57) Write an ALP for 8086 to transmit a set of 100 characters using
8251 USART. Assume the register addresses
58) Specify the mode word of 8251 USART for the following:
(i)Asynchronous mode.
(ii) 1x64 Baud rate factor.
(iii) 8-bit character
(iv) Odd parity
(v) Two stop bits.
59) What do you understand by priority of a device?
When does the need for defining priority arises.
60) How is the priority determined in case of
(i) soft-ware polled interrupts and
(ii) hard-ware polled interrupts.
61) Is it possible to change the priority when
(i) software polling
(ii) hard-ware polling is used? If so how it can be done?
62) Explain briefly the various modes available in 8253 timer chip.
Give an initialization sequence for generating a 1 kHz square wave.
Assume a 2MHz clock is available.
63) With the help of a block diagram, give the details of how a PIC 8259
is interfaced to 8086. Explain the functions of all control signals used.
64) How do you interface a CRT data terminal to an 8086 CPU using 8251 USART?
Discuss the hardware and software aspects of interface.
65) Distinguish between synchronous and asynchronous data
transfer methods with examples.
66) Keyboard / Display interface. What is “On the fly”
operation in 8253?
67) Design the hardware and software required for 8085 or 8086 based
system for accepting data from an encoded ASCII keyboard and sending
out the same data to a serial output device with 7-bit data, even parity,
1 stop bit and 1200 baud using USART. Use a Programmable Interval
Timer for clocking the USART and programmable keyboard and display
interface for ASCII keyboard.
68) Programmable features of 8259
69) Various modes of operation of 8253-Timer-interface.
70) Programmable features of 8259
71) Give the status register details of peripheral IC-8279.
72) 8253 Timer Architecture (c) Programming 8279
UNIT – IV
73) What is the necessity of sample and hold circuit in interfacing
ADC to Microprocessor?
74) Explain the various methods of Analog to Digital conversion
techniques and compare their performances.
75) Explain how an 8-bit ADC is interfaced to 8085
or 8086 microprocessor.
76) What is “short cycle” operation of an ADC and when is it used?
77) Calculate the resolution of a 12-bit D/A converter for a 10V maximum range.
78) What do you understand by ± ½ LSB specification in data converters?
79) Draw the logic diagram of a hardware structure to support
software driven A/D conversion. A 10-bit DAC, comparator,
Tri-state buffer, and logic for device selection is all the hardware
to be used. The DAC is to be treated as if it were a 1024 x 1 block
of memory. The data inputs of DAC are to be connected to the address
bus. Describe the timing constraints on the circuit for it to operate properly.
Write a subroutine that implements a counting type A/D converter
with this hardware. Assume either 8085 or 8086 μP for implementation.
80) What are the different Digital to Analog Converter methods ?
Explain one of the methods in detail for a 4-bit DAC with
suitable numerical assignment.
81) Generate a saw-tooth waveform of amplitude 5 V and
frequency of 10 kHz by interfacing an 8-bit DAC to
8086-based system.
82) DAC and ADC specifications
83) A 12-bit ADC is operating with 1Sec clock period and
the total conversion time is seen to be 14Secs.
Write the type of this ADC with a brief justification.
84) Write clearly the complete specifications of 8-bit DAC device
and 8-bit ADC device.
85) Write both hardware and software to implement 8-bit ADC
using 8-bit DAC by interfacing 8-bit DAC to 8085 based system
UNIT – V
86) Write an 8051 assembly language program to add an array of numbers
stored in memory.
87) Give the difference between Microprocessor and Microcontroller.
Draw the block diagram of 8051 and explain the function of each block.
88) Write an 8051 Assembly Language program to find the average of „N‟-numbers.
89) Mention all possible interrupts with 8051 micro-controller and
give their vector addresses.
90) Explain in detail the Timer/Counter operation of 8051 micro-controller.
91) Explain why mode „O‟ is not suitable for 8051 communications.
Explain in detail mode „1‟ operation of UART in 8051.
92) What are the differences between 8031 and 8051 microcontrollers?
93) Explain the different methods of operations of Timer/Counter
of 8051 microcontroller.
94) Distinguish between Microprocessors and Microcontrollers.
95) Explain addressing Modes of 8051 with example instructions
and Numerical value assignment. Write 8051 Assembly language
Program that transfers a block of data from source address to
destination address. Assume suitable data.
96) What are the important features of 8051?
97) Write briefly 8051 architectural features. Write 8051 assembly
language program to read 4-bit binary number from an input port
and display its 2‟s complement value on a 7-segment LED display
at an output port.
UNIT – VI
98) ROM BIOS and BIOS function calls.
99) BIOS function calls.
100) What are the uses of BIOS function calls?
101) DOS function calls.
102) Describe briefly the hardware and software aspects of PC Architecture.
103) Distinguish between BIOS function call and DOS function call.
104) Briefly discuss about hardware organization of IBM compatible PC.
Write either assembly language program or high level program to read a
character from keyboard and display on the screen of PC continuously
using DOS function calls.
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