ANNA UNIVERSITY COIMBATORE-SYLLABUS

MICROPROCESSOR AND APPLICATIONS

UNIT I 8 BIT MICROPROCESSOR ARCHITECTURE 9

8085-Internal Architecture - Addressing modes - Instruction set -Timing diagrams-Interrupts-Assembly language Programming

UNIT II 16 BIT MICROPROCESSOR ARCHITECTURE 9

8086-Internal Architecture -Memory segmentation -Timing diagram - Interrupts-8086CPU Hardware design- Maximum mode CPU Module - Minimum mode CPU module

UNIT III 8086 INSTRUCTION SET & ASSEMBLY LANGUAGE 9PROGRAMMING

Addressing modes - Instruction set- Data transfer instructions- String instructions-Logical Instructions Arithmetic Instructions Transfer of control instructions -Processorcontrol Instructions -Assembly language programming –Assembler-

UNIT IV SPECIAL PURPOSE SUPPORT DEVICES 9

8255A -Programmable peripheral interface - 8251A USART -8279- keyboard and displaycontroller -8259 programmable Interrupt controller -8257 DMA controller -8254programmable interval timer -digital to analog and analog to digital converters

UNIT V MEMORY AND I/O INTERFACING 9

Types of Main memory- SRAM -interfacing- DRAM -interfacing -I/O interfacing-programmed I/O- Interrupt Driven I/O- DMA Interfacing Microcomputer to high powerdevices - Optical Motor shaft Encoders

TEXT BOOKS:

1. Douglas V-Hall “Microprocessor and interfacing “2/E –TMH,2002.2. Walter A-Tribel & Avtar Singh “The 8088 and 8086 Microprocessors

programming -Interfacing -software -Hardware and Application” 4/EPearson/PHI 2003.

REFERENCES:

3. John Uffenbeck “Microcomputer and Microprocessors” The 8080-8085 and Z-80programming –“Interfacin

4. g and Troubleshooting” 3rd Edition- -Pearson Education,20005. John Uffenbeck “ The 8086 family Design-programming and interfacing”-3/E-

pearson Education6. Ramesh Gaonkar-“Microprocessor Architecture Programming and Application

with 8085”-Penram Publications pvt Ltd-5 E/Pearson 2000 .

DEPARTMENT OF ECE Microprocessor and application

UNIT - IPART-A

1. What is Microprocessor?It is a program controlled semiconductor device (IC}, which fetches, decodes and

executes instructions.

2. What are the basic units of a microprocessor?The basic units or blocks of a microprocessor are ALU, an array of registers and control

unit.

3. What is Software and Hardware?The Software is a set of instructions or commands needed for performing a

specific task by a programmable device or a computing machine.The Hardware refers to the components or devices used to form computing machine

in which theSoftware can be run and tested. Without software the Hardware is an idle machine.

4. Define bit, byte and word.A digit of the binary number or code is called bit. Also, the bit is the fundamental

storage unit of computer memory. The 8-bit (8-digit) binary number or code is called byteand 16-bit binary number or code is called word. (Some microprocessor manufactures referthe basic data size operated by the processor as word).

5. What is a bus?Bus is a group of conducting lines that carries data, address and control signals.

6. Why data bus is bi-directional?The microprocessor has to fetch (read) the data from memory or input device for

processing and after processing, it has to store (write) the data to memory or output device.Hence the data bus is bi-directional.

7. Why address bus is unidirectional?The address is an identification number used by the microprocessor to identify or access

a memory location or I / O device. It is an output signal from the processor. Hence the addressbus is unidirectional.

8. What is the function of microprocessor in a system?The microprocessor is the master in the system, which controls all the activity of the

system. It issues address and control signals and fetches the instruction and data from memory.Then it executes the instruction to take appropriate action.

9. Define machine cycle.Machine cycle is defined as the time required to complete one operation of accessing

memory, I/O, or acknowledging an external request. This cycle may consist of three to six T-states.

10. Define T-State.T-State is defined as one subdivision of the operation performed in one clock period.

These subdivisions are internal states synchronized with the system clock, and each T-Stateis precisely equal to one clock period.

11. What is the need for system clock and how it is generated in 8085?The system clock is necessary for synchronizing various internal operations or devices

in the microprocessor and to synchronize the microprocessor with other peripherals in thesystem.

12.Draw and specify the complete bit configuration of 8085 flag Register?D7 D6 D5 D4 D3 D2 D1 D0

S Z AC P CY

S- Sign Flag . If D7 =1 , then sign flag is set, otherwise rest.Z-Zero flag. If ALU operation results in zero, then this flag is set,

Otherwise it is reset.AC-Auxilliary flag. In an arithmetic operation ,when a carry is generated by

digit D3 and passed on to digit D4, the AC flag is set.Otherwise it is reset.

P-Parity Flag. If the result of an arithmetic or logic operation has an evennumber of 1’s then this flag is set. Otherwise it is reset.

CY-Carry Flag. If an arithmetic operation results in a carry, the carry flagis set. Otherwise it is reset.

13. List the four operations commonly performed by MPU( Micro processingUnit)?• Memory Read : Reads data (or instructions) from memory.• Memory Write: Writes Data (or instructions) into memory.• I/O Read: Accepts data from input devices.

14. What is the need for timing diagram?The timing diagram provides information regarding the status of various signals,

when a machine cycle is executed. The knowledge of timing diagram is essential for systemdesigner to select matched peripheral devices like memories, latches, ports, etc., to form amicroprocessor system.

15. Define opcode and operand.Opcode (Operation code) is the part of an instruction / directive that identifies a specific

operation.Operand is a part of an instruction / directive that represents a value on which the

instruction acts.

16. What are the functions of an accumulator?The accumulator is the register associated with the ALU operations and sometimes

I/O operations. It is an integral part of ALU. It holds one of data to be processed by ALU. It alsotemporarily stores the result of the operation performed by the ALU.

17. List the 16 – bit registers of 8085 microprocessor.Stack pointer (SP) and Program counter (PC).

18. List the allowed register pairs of 8085.• B-C register pair• D-E register pair• H-L register pair

19. Mention the purpose of SID and SOD linesSID (Serial input data line):

It is an input line through which the microprocessor accepts serialdata.

SOD (Serial output data line):It is an output line through which the microprocessor sends outputserial data.

20. What is the function of IO/M signal in the 8085?It is a status signal. It is used to differentiate between memory locations and I/O

operations. When this signal is low (IO/M = 0) it denotes the memory related operations. Whenthis signal is high (IO/M = 1) it denotes an I/O operation.

21. List out the five categories of the 8085 instructions. Give examples of the instructionsfor each group.

• Data transfer group – MOV, MVI, LXI.• Arithmetic group – ADD, SUB, INR.• Logical group –ANA, XRA, CMP.• Branch group – JMP, JNZ, CALL.• Stack I/O and Machine control group – PUSH, POP, IN, HLT.

22. Explain the difference between a JMP instruction and CALL instruction.A JMP instruction permanently changes the program counter. A CALL

instruction leaves information on the stack so that the original program execution sequencecan be resumed.

23. Explain the purpose of the I/O instructions IN and OUT. The IN instruction is used to move data from an I/O port into the

accumulator. The OUT instruction is used to move data from the accumulator to an I/O port. The IN & OUT instructions are used only on microprocessor, which use a Separate address space for interfacing.

24. What is the difference between the shift and rotate instructions?A rotate instruction is a closed loop instruction. That is, the data moved out at one end is

put back in at the other end. The shift instruction loses the data that is moved out of the last bitlocations.

25. What is meant by Wait State?This state is used by slow peripheral devices. The peripheral devices can transfer the data

to or from the microprocessor by using READY input line. The microprocessor remains in waitstate as long as READY line is low. During the wait state, the contents of the address,address/data and control buses are held constant.

26. List the four instructions which control the interrupt structure of the 8085microprocessor.

• DI ( Disable Interrupts )• EI ( Enable Interrupts )• RIM ( Read Interrupt Masks )• SIM ( Set Interrupt Masks )

27. What is meant by polling?Polling or device polling is a process which identifies the device that has interrupted the

microprocessor.

28. What is meant by interrupt?Interrupt is an external signal that causes a microprocessor to jump to a specific

subroutine.

29. Explain priority interrupts of 8085.The 8085 microprocessor has five interrupt inputs. They are TRAP, RST 7.5, RST 6.5,

RST 5.5, and INTR. These interrupts have a fixed priority of interrupt service. If two ormore interrupts go high at the same time, the 8085 will service them on priority basis. TheTRAP has the highest priority followed bye RST 7.5, RST 6.5, RST 5.5. The priority ofinterrupts in 8085 is shown in the table.

Interrupts Priority

TRAPRST 7.5RST 6.5RST 5.5INTR

12345

30. What is a microcomputer?A computer that is designed using a microprocessor as its CPU is called

microcomputer.

31. What are operations performed on data in 8085The various operations performed are

• Store 8-bit data• Perform arithmetic and logical operations• Test for conditions• Sequence the execution of instructions• Store data temporarily during execution in the defined R/W

memory locations called the stack

32. Steps involved to fetch a byte in 8085i. The PC places the 16-bit memory address on the address busii. The control unit sends the control signal RD to enable the memory chip

iii. The byte from the memory location is placed on the data busiv. The byte is placed in the instruction decoder of the microprocessor and the

task is carried out according to the instruction

33. Define instruction cycle, machine cycle and T-stateInstruction cycle is defined, as the time required completing the execution of an

instruction. Machine cycle is defined as the time required completing one operation ofaccessing memory, I/O or acknowledging an external request. T- cycle is defined as onesubdivision of the operation performed in one clock period

34. What is an instruction?An instruction is a binary pattern entered through an input device to command the

microprocessor to perform that specific function

30. What is the use of ALEThe ALE is used to latch the lower order address so that it can be available in T2 and T3

and used for identifying the memory address. During T1 the ALE goes high, the latch istransparent ie, the output changes according to the input data, so the output of the latch is thelower order address. When ALE goes low the lower order address is latched until the next ALE.

35. How many machine cycles does 8085 have, mention themThe 8085 have seven machine cycles. They are

• Opcode fetch• Memory read• Memory write• I/O read• I/O write• Interrupt acknowledge• Bus idle

36. Explain the signals HOLD, READY and SIDHOLD indicates that a peripheral such as DMA controller is requesting the use of

address bus, data bus and control bus. READY is used to delay the microprocessor read orwrite cycles until a slow responding peripheral is ready to send or accept data. SID is used toaccept serial data bit by bit37. Mention the categories of instruction and give two examples for eachCategory?

The instructions of 8085 can be categorized into the following five

• Data transfer MOV Rd,Rs STA 16-bit• Arithmetic ADD R DCR M• Logical XRI 8-bit RAR• Branching JNZ CALL 16-bit• Machine control HLT NOP

38. Explain LDA, STA and DAA instructionsLDA copies the data byte into accumulator from the memory location specified by

the 16-bit address. STA copies the data byte from the accumulator in the memory locationspecified by 16-bit address. DAA changes the contents of the accumulator from binary to 4-bit BCD digits.

39. Explain the different instruction formats with examplesThe instruction set is grouped into the following formats

• One byte instruction MOV C,A• Two byte instruction MVI A,39H• Three byte instruction JMP 2345H

40. What is the use of addressing modes, mention the different typesThe various formats of specifying the operands are called addressing modes, it is used

to access the operands or data. The different types are as follows• Immediate addressing• Register addressing• Direct addressing• Indirect addressing• Implicit addressing

41. What is the use of bi-directional buffers?It is used to increase the driving capacity of the data bus. The data bus of a

microcomputer system is bi-directional, so it requires a buffer that allows the data to flow inboth directions.

42. Give the register organization of 8085

W(8) Temp. Reg Z(8) Temp. Reg

B(8) Register C(8) Register

D(8) Register E(8) Register

H(8) Register L(8) Register

Stack Pointer(16)

Program Counter(16)

43. Define stack and explain stack related instructionsThe stack is a group of memory locations in the R/W memory that is used for the

temporary storage of binary information during the execution of the program. The stackrelated instructions are PUSH & POP

44. Why do we use XRA A instructionThe XRA A instruction is used to clear the contents of the Accumulator and store the

value 00H.

45. Compare CALL and PUSH instructionsCALL PUSH

When CALL is executed themicroprocessor automatically stores the16-bit address of the instruction next toCALL on the stack

The programmer uses the instructionPUSH to save the contents of the registerpair on the stack

When CALL is executed the stack pointeris decremented by two

When PUSH is executed the stackpointer register is decremented by two

46. What is opcode fetch cycle?The opcode fetch cycle is a machine cycle executed to fetch the opcode of an instruction

stored in memory. Every instruction starts with opcode fetch machine cycle.

47. What operation is performed during first T -state of every machine cycle in 8085 ?In 8085, during the first T -state of every machine cycle the low byte address is

latched into an external latch using ALE signal.

48. Why status signals are provided in microprocessor?The status signals can be used by the system designer to track the internal operations of

the processor. Also, it can be used for memory expansion (by providing separate memorybanks for program & data and selecting the bank using status signals).

49. How the 8085 processor differentiates a memory access (read/write)and 1/0 access(read/write)?

The memory access and 1/0 access is differentiated using 10 I M signal. The 8085processor asserts 10 I M low for memory read/write operation and 10 I M is asserted highfor 1/0 read/write operation.

50. What is interrupt acknowledge cycle?The interrupt acknowledge cycle is a machine cycle executed by 8085 processor to get

the address of the interrupt service routine in-order to service the interrupt device.

51. How the interrupts are affected by system reset?Whenever the processor or system is resetted , all the interrupts except TRAP are

Disabled. fu order to enable the interrupts, El instruction has to be executed after a reset.

52. What is the difference between Hardware and Software interrupt?The Software interrupt is initiated by the main program, but the Hardware

interrupt is initiated by an external device. In 8085, the Software interrupt cannot be disabledor masked but the hardware interrupt except TRAP can be disabled or masked.

53. What is Vectored and Non- Vectored interrupt?When an interrupt is accepted, if the processor control branches to a specific address

defined by the manufacturer then the interrupt is called vectored interrupt. In Non-vectored interrupt there is no specific address for storing the interrupt service routine. Hencethe interrupted device should give the address of the interrupt service routine.

54. List the Software and Hardware interrupts of 8085?Software interrupts: RST 0, RSTl, RST 2, RST 3, RST 4, RST 5, RST 6 and RST7.Hardware interrupts: TRAP, RST 7.5, RST 6.5, RST 5.5 and INTR.

55. What is TRAP?The TRAP is non-maskable interrupt of8085. It is not disabled by processor reset

or after reorganization of interrupt.

56. Whether HOLD has higher priority than TRAP or not?The interrupts including mAP are recognized only if the HOLD is not valid, hence

TRAP has lower priority than HOLD.

57. What is masking and why it is required?Masking is preventing the interrupt from disturbing the current program

execution.When the processor is performing an importantjob(process)and if the processshould not be interrupted then all theinterrupts should be masked or disabled. In processor with multiple 'interrupts, the lowerpriority interrupt can be masked so as to prevent it from interrupting, the execution ofinterrupt service routine of higher priority interrupt.

58. When the 8085 processor accept hardware interrupt?The processor keeps on checking the interrupt pins at the second T -state of last

Machine cycle of every instruction. If the processor finds a valid interrupt signal and ifthe interrupt is unmasked and enabled then the processor accepts the interrupt. Theacceptance of the interrupt is acknowledged by sending an OOA signal to the interrupteddevice.

59. When the 8085 processor will disable the interrupt system?The interrupts of 8085 except TRAP are disabled after anyone of the following

operations1. Executing El instruction.2. System or processor reset.3. After reorganization (acceptance) of an interrupt.

60. How the vector address is generated for the INTR interrupt of 8085?For the interrupt INTR, the interrupting device has to place either RST opcode or

CALL opcode followed by l6-bit address. I~RST opcode is placed then the correspondingvector address is generated by the processor. In case of CALL opcode the given l6-bit addresswill be the vector address.

61. How clock signals are generated in 8085 and what is the frequency of the internalclock?

The 8085 has the clock generation circuit on the chip but an external quartz crystal orL C circuit or RC circuit should be connected at the pins XI and X2. The maximum internalclock frequency of 8085A is 3.03 MHz.

62. What happens to the 8085 processor when it is resetted?When the 8085 processor is resetted it execute the first instruction at the 0000H

location. The 8085 resets (clears) instruction register, interrupt mask bits and other registers.

63. What are the operations performed by ALU of 8085?The operations performed by ALU of 8085 are Addition, Subtraction, Logical AND,

OR, Exclusive OR, Compare Complement, Increment, Decrement and Left I Right shift

64. What is a flag?Flag is a flip flop used to store the information about the status of the processor and the

status of the instruction executed most recently.

65. Where is the READY signal used?READY is an input signal to the processor, used by the memory or I/O devices to get

extra time for data transfer or to introduce wait states in the bus cycles.

66. What is HOLD and HLDA and how it is used?Hold and hold acknowledge signals are used for the Direct Memory Access (DMA)

type of data transfer. The DMA controller place a high on HOLD pin in order to take controlof the system bus. The HOLD request is acknowledged by the 8085 by driving all its tristatedpins to high impedance state and asserting HLDA signal high.

67.What is Polling?Polling is a scheme or an algorithm to identify the devices interrupting the processor.

Polling is employed when multiple devices interrupt the processor through one interrupt pin ofthe processor.

68. What are the different types of Polling?The polling can be classified into software and hardware polling. In software polling

the entire polling process is govern by a prograrn.1n hardware polling, the hardware takes careof checking the status of interrupting devices and allowing one by one to the processor.

69. Define stackStack is a sequence of RAM memory locations defined by the programmer.

70. What is program counter? How is it useful in program execution?The program counter keeps track of program execution. To execute a program the

starting address of the program is loaded in program counter. The PC sends out an address tofetch a byte of instruction from memory and increments its content automatically.

71. How the microprocessor is synchronized with peripherals?The timing and control unit synchronizes all the microprocessor operations with clock

and generates control signals necessary for communication between the microprocessor andperipherals.

72. What is a minimum system and how it is formed in 8085?A minimum system is one which is formed using minimum number of IC chips, The

8085 based minimum system is formed using 8155,8355 and 8755.

73.Give some examples of port devices used in 8085 microprocessor based system?The various INTEL I/O port devices used in 8085 microprocessor based system are 8212,

8155, 8156, 8255, 8355 and 8755.

74.Write the uses of microprocessors in Medical Instrumentation field?Patient Monitoring in Intensive Care Unit, Pathological Analysis and the measurement of

parameters like blood pressure and temperature.

75. Define Real Time Systems :Real Time Systems are those in which timeliness is as important as the correctness of the

outputs, although this does not mean that they have to be “fast systems”.

76. List the limitations of 8 bit microprocessor: Lower Execution Speed It can address less memory size Few instructions are available

77. What do you mean ‘ Data Width’?Data Width is the width of the ALU. An 8 bit ALU can add / subtract/ multiply etc..

two 8 bit numbers . In many cases, the external data bus is the same width as the ALU, butnot always. The 8088 had a 16 bit ALU and 8 bit bus , while the modern Pentiums fetch data64 bits at a time for their 32 bit ALUs.

Part B

1. Draw and Explain the operation of 8085 and its architecture?2. Draw and Explain the pin configuration of 8085?3. Explain the instruction set with example?4. Draw the timing diagram for LDA address and LHLD address?5. Draw and Explain the Interrupt structure of 8085?6. Write a program to transfer a block of data from one location to the other?7. Write an ALP to convert a two digit BCD data to Binary data?8. Write a program to sort the numbers in ascending and descending order?9. Name the different Addressing modes used in 8085 instruction set and explain about each

one with suitable example?10. Write a program to generate a delay of 0.6 sac for the given crystal frequency of 5 Mhz?

Unit - IIPart A

1. What is the purpose of segment registers in 8086?There are 4 segment registers present in 8086. They are

1. Code Segment (CS ) register2. Data Segment (DS ) register3. Stack Segment (SS ) register4. Extra Segment (ES ) register

The code segment register gives the address of the current code segment. ie. Itwill points out where the instructions, to be executed, are stored in the memory. The datasegment register points out where the operands are stored in the memory. The stacksegment registers points out the address of the current stack, which is used to store thetemporary results. If the amount of data used is more the Extra segment register pointsout where the large amount of data is stored in the memory.

2. Define pipelining?In 8086, to speedup the execution of program, the instructions fetching and execution of

instructions are overlapped each other. This technique is known as pipelining. In pipelining,when the n th instruction is executed, the n+1 th instruction is fetched and thus the processingspeed is increased.

3. Discuss the function of instruction queue in 8086?In 8086, a 6-byte instruction queue is presented at the Bus Interface Unit

(BIU). It is used to prefetch and store at the maximum of 6 bytes of instruction code fromthe memory. Due to this, overlapping instruction fetch with instruction execution increasesthe processing speed.

4. What is the maximum memory size that can be addressed by 8086?In 8086, an memory location is addressed by 20 bit address and the address bus is 20

bit address and the address bus is 20 bits. So it can address up to one mega byte (2^20) ofmemory space.

5. What is the function of the signal in 8086?BHE signal means Bus High Enable signal. The BHE signal is made low when

there is some read or write operation is carried out. ie . When ever the data bus of thesystem is busy i.e. whenever there is some data transfer then the BHE signal is made low.

6.What are the predefined interrupts in 8086?The various predefined interrupts are,

DIVISION BY ZERO (type 0) Interrupt.SINGLE STEP (type 1) Interrupt.NONMASKABLE (type2) Interrupt.BREAK POINT (type 3) Interrupt. OVERFLOW (type 4) Interrupt.

7. List the various addressing modes present in 8086?

There are 12 addressing modes present in 8086. They are,(a) Register and immediate addressing modes

Register addressing modesImmediate addressing mode

(b) Memory addressing modes.Direct addressing modesRegister indirect addressing modesBased addressing modesIndexed addressing modesBased Indexed addressing modesString addressing modes

(c) I/O addressing modesDirect addressing modeIndirect addressing mode

(d) Relative addressing mode(e) Implied addressing mode

8. How single stepping can be done in 8086?By setting the Trace Flag (TF) the 8086 goes to single-step mode. In this mode, after

the execution of each instruction s 8086 generates an internal interrupt and by writing someinterrupt service routine we can display the content of desired registers and memory locations.So it is useful for debugging the program.

9. State the significance of LOCK signal in 8086?If 8086 is working at maximum mode, there are multiprocessors are present. If the

system bus is given to a processor then the LOCK signal is made low. That means thesystem bus is busy and it cannot be given of any other processors. After the use of thesystem bus again the LOCK signal is made high. That means it is ready to give the system busto any processor.

10. What are the functions of bus interface unit (BIU) in 8086?(a) Fetch instructions from memory.(b) Fetch data from memory and I/O ports. (c)Write data to memory and I/O ports.(d) To communicate with outside world.(e) Provide external bus operations and bus control signals.

11. What is the clock frequency of 8086?8086 8086-2 8086-4

Internal clock FrequencyExternal Clock Frequency

5 MHz15MHZ

8MHz24MHZ

4MHz12MHZ

12. What are the two modes of operations present in 8086?i. Minimum mode (or) Uniprocessor system

ii. Maximum mode (or) Multiprocessor system

13. Explain REPEAT-UNTIL statementsREPEAT-UNTIL statements allow executing a series of instructions repeatedly

until some condition occurs. The REPEAT defines the start of the loop & UNTILthe end of the loop. UNTIL has a condition when the condition is true the loop isterminated

14. What are the modes in which 8086 can operate?The 8086 can operate in two modes and they are minimum (or uniprocessor) mode and

maximum (or multiprocessor) mode.

15. What is the data and address size in 8086?The 8086 can operate on either 8-bit or 16-bit data. The 8086 uses 20 bit address to

access memory and 16-bit address to access 1/0 devices.

16. Explain the function of M/IO in 8086.The signal M/IO is used to differentiate memory address and 1/0 address When

the processor is accessing memory locations MI 10 is asserted high and when it is accessing 1/0mapped devices it is asserted low.

17. Write the flags of 8086.The 8086 has nine flags and they are1. Carry Flag (CF) 6. Overflow Flag (OF)2. Parity Flag (PF) 7. Trace Flag (TF)3. Auxiliary carry Flag (AF) 8. Interrupt Flag (IF)4. Zero Flag (ZF) 9. Direction Flag (DF)5. Sign Flag (SF)

18. How clock signal is generated in 8086? What is the maximum internal clock frequencyof 8086?

The 8086 does not have on-chip clock generation circuit. Hence the clockgenerator chip, 8284 is connected to the CLK pin of8086. The clock signal supplied by8284 is divided by three for internal use. The maximum internal clock frequency of8086 is5MHz.

19. Write the special functions carried by the general purpose registers of 8086.The special functions carried by the registers of 8086 are the following. Register

Special function1. AX 16-bit Accumulator2. AL 8-bit Accumulator3. BX Base Register4. CX Count Register5. DX .Data Register

20. What are the functional units available in 8086 architecture?The bus interface unit and execution unit are the two functional units available in 8086

architecture.

21. List the segment registers of 8086.The segment registers of 8086 are Code segment, Data segment, Stack segment and

Extra segment registers.

22. What is the difference between CPU bus and system bus?The CPU bus has multiplexed lines but the system bus has separate lines for each

signal. (The multiplexed CPU lines are demultiplexed by the CPU interface circuit to formsystem bus).

23. How do 8086 interrupts occurAn 8086 interrupt can come from any of the following three sources

• External signals• Special instructions in the program• Condition produced by instruction

24. What are the 8086 interrupt typesDedicated interrupts

• Type 0: Divide by zero interrupt• Type 1: Single step interrupt• Type 2:Non maskable interrupt• Type 3: Breakpoint• Type 4: Overflow interrupt

Software interrupts• Type 0-255

25. What is interrupt service routineInterrupt means to break the sequence of operation. While the CPU is executing a

program an interrupt breaks the normal sequence of execution of instructions & diverts itsexecution to some other program. This program to which the control is transferred is called theinterrupt service routine.

26. When the 8086 processor is in minimum mode?The processor 8086 is in minimum mode when its MN/MX pin is strapped to +5 V

27. When the 8086 processor is in maximum mode?The processor 8086 is in maximum mode when its MN/MX pin is grounded.

28. List the functions of Bus Interface Unit in 8086.• Sends out addresses• Fetches instructions from memory• Reads data from ports and memory• Writes data to port and memory

29. Write any two advantages of segment registers in 8086a. It allows the memory capacity to be 1MB even though the addressassociated with individual instructions are 16 bits wide.b. It allows the instruction,data, or stack portion of a program to be more than

64KB long by using more than one code, data, or stack segment

30. What is the use of Instruction pointer in 8086 ?

Instruction pointer holds the 16 bit address of the next code byte within the codesegment. The value contained in the IP is called effective address or offset. It contains thedistance from the base address to the next instruction byte to be fetched.

31. Write about the auxiliary carry flag used in 8086 ?It is set if there is a carry out of bit 3 during an addition or a borrow by bit 3 during a

subtraction. This flag is used exclusively for BCD arithmetic.

32. When the Overflow flag is set ?For addition of 16 bits, this flag is set when there is a carry into the MSB and no carry

out of the MSB.

Part B

1. Draw and explain the functions of 8086 architecture2. Explain the minimum mode & maximum mode signal?3. Draw and explain the timing diagram minimum mode & maximum mode signal?4. Explain the interrupts with interrupt structure?5. State the function of direction flag in 8086?

UNIT – IIIPart A

1.Define Register Relative Addressing Mode.Register Relative Addressing Mode : The Effective Address is Calculated by the sum

of 8- or 16 bit displacement and the contents of a base Register or an index Register.E.A. = content of(BX or BP or SI or DI) + (8 bit displacement (sign

extended ) or 16 bit displacementPhysical Address = E.A +(DS)*1610

2. Define Immediate Addressing.An 8 bit or 16 bit immediate data follows the instruction. For e.g MOV AX,5020H

instruction transfers a word 5020H to the AX register.

3. Define EQU directive in 8086 assembly language?It is used to assign a name to constants used in the programs. Consider the statement

‘corr EQU 07H’ , this would tell the assembler to insert the value 07H everytime that itfinds the name corr in the program statement.

4. Write the use of Assume directive in 8086 assembly language using one example?Assume CS: code_here, DS:data_here It tells the assembler that the logical segment

code_here contains the instruction statements for the program and should be treated as a codesegment. It also tells the assembler that it should treat the logical segment data_here as thedata segment for this program.

5. Define EXTRN directive in in 8086 assembly language?The EXTRN directive is used to inform the assembler that the names or labels

following the directive are in some other assembly module.

6. What is the use of TEST instruction in 8086?Test instruction is the same as the AND instruction except that ite does not put the result

anywhere. Like the CMP instruction , it is used only to set the flags.

7. Define LAHF and SAHF instructions in 8086.LAHF : Load the 8085 equivalent flags into the AH register.SAHF: Store the AH register into the low order byte of the flag register.

8. While handling the interrupt instructions in 8086. What are the internal operations may becarried out by the stack?

(i)SP =SP-2 , stack Push flag reg. Contents, IF =0 , TF =0(ii) SP=SP-2, Stack CS Reg. Contents, Address of Interrupt pointer = Interrupttype * 4 , CS Register Contents Second word of Interrupt pointer (iii) SP=SP-2,Stack IP, IP First word of Interrupt pointer

9. Write an ALP program in 8086 to add two 16 bit numbers.MOV AX,1236HMOV BX,8765HADD AX,BX HLT

10. What is assemblerThe assembler translates the assembly language program text which is given as input to

the assembler to their binary equivalents known as object code. The time required to translatethe assembly code to object code is called access time. The assembler checks for syntax errors &displays them before giving the object code.

11. What is loaderThe loader copies the program into the computer’s main memory at load time and

begins the program execution at execution time.

12. What is linkerA linker is a program used to join together several object files into one large

object file. For large programs it is more efficient to divide the large program modulesinto smaller modules. Each module is individually written, tested & debugged. Whenall the modules work they are linked together to form a large functioning program.

13. Explain ALIGN & ASSUMEThe ALIGN directive forces the assembler to align the next segment at an address

divisible by specified divisor. The format is ALIGN number where number can be 2, 4, 8 or 16.Example ALIGN 8.

The ASSUME directive assigns a logical segment to a physical segment at anygiven time. It tells the assembler what address will be in the segment registers atexecution time. Example ASSUME CS: code, DS: data, SS: stack

14. Explain PTR & GROUPA program may contain several segments of the same type. The GROUP directive

collects them under a single name so they can reside in a single segment, usually a datasegment. The format is Name GROUP Seg-name,…..Seg-name

PTR is used to assign a specific type to a variable or a label. It is also usedto override the declared type of a variable.

15. Explain about MODELThis directive provides short cuts in defining segments. It initializes memory

model before defining any segment. The memory model can be SMALL, MEDIUM,COMPACT or LARGE.

Model Code segments Data segmentsSmall One OneMedium Multiple OneCompact One MultipleLarge Multiple Multiple

16. Explain PROC & ENDPPROC directive defines the procedures in the program. The procedure name must

be unique. After PROC the term NEAR or FAR are used to specify the type of procedure.Example FACT PROC FAR. ENDP is used along with PROC and defines the end of theprocedure.

17. Explain SEGMENT & ENDSAn assembly program in .EXE format consists of one or more segments. The starts of

these segments are defined by SEGMENT and the end of the segment is indicated by ENDSdirective. Format Name SEGMENT Name ENDS

18. Explain TITLE & TYPEThe TITLE directive helps to control the format of a listing of an assembled

program. It causes a title for the program to print on line 2 of each page of theprogram listing.

Maximum 60 characters are allowed. Format TITLE text.TYPE operator tells the assembler to determine the type of specified variable

in bytes. For bytes the assembler gives a value 1, for word 2 & double word 4.

19. Define SOPThe segment override prefix allows the programmer to deviate from the default

segmentEg : MOV CS : [BX] , AL

20. Define variableA variable is an identifier that is associated with the first byte of data item.

In assembly language statement: COUNT DB 20H, COUNT is the variable.

21. What are proceduresProcedures are a group of instructions stored as a separate program in memory and

it is called from the main program whenever required. The type of procedure depends onwhere the procedures are stored in memory. If it is in the same code segment as that ofthe main program then it is a near procedure otherwise it is a far procedure.

22. Explain the linking processA linker is a program used to join together several object files into one large

object file. The linker produces a link file which contains the binary codes for all thecombined modules. It also produces a link map which contains the address informationabout the link files. The linker does not assign absolute addresses but only relative addressstarting from zero, so the programs are relocatable & can be put anywhere in memory to berun.

23. What are librariesLibrary files are collection of procedures that can be used in other

programs.These procedures are assembled and compiled into a library file by the LIBprogram. The library file is invoked when a program is linked with linker program. whena library file is linked only the required procedures are copied into the program. Use oflibrary files increase s/w reusability & reduce s/w development time.

24. Write about EVEN directive in 8086 ALP.It forces the address of the next byte to be even. 8086 words can be accessed in less

time if they begin at even address.

25. Write about the following instruction : CallWORD PTR [BX]

Offset of the first instruction of procedure is in two memory addresses inDS. It replaces the contents of IP with contents of word memory locations in DSpointed to by BX.

26. Define Direct Addressing mode :A 16 bit offset address of the data memory location is specified with reference to the

DS segment starting address.For.E.g MOV [1020H],5020H instruction transfers a word 5020H to the data memory

location at 11020H if DS=1000H.

27. Define Relative based indexed addressing mode:Relative Based Indexed Addressing Mode : Effective Address is calculated by the

sum of 8- or 16 bit displacement and a based indexed address.E.A.= (BX or BP) + (SI or DI) +( 8 bit displacement (sign extended ) or 16 bit

displacement)Physical Address= E.A + (DS)*1610

28. List the branch related addressing mode:• Intra segment Direct• Intra segment Indirect• Inter segment Direct• Inter Segment Indirect

29. Define Register addressing mode:Datum is in the register that is specified by the instruction

E.g : MOV CX,AX (16 bit operand)MOV CL,AL ( 8 bit operand)

30. Define Register Indirect Addressing mode:Effective address of the datum is in the base register BX or an index register

that is specified by the instruction.

31. Define Register relative addressing mode:The effective address is the sum of an 8- or 16 bit displacement and the contents of

a base register or an index register.

32. Define Based Indexed addressing mode:The effective address is the sum of a base register and an index register , both of

which are specified by the instruction. It is also called as Base related Indexedaddressing.

33. Define Intra segment direct addressing mode:The effective branch address is the sum of an 8- or 16 bit displacement and the

current contents of IP.

34. Define Intra segment Indirect addressing mode:The effective branch address is the contents of a register or memory location

that is accessed using any of the data related addressing modes except the immediate mode.The contents of IP are replaced by the effective branch address.

35. Define Inter segment addressing mode:It replaces the contents of IP with part of the instruction and the contents of CS

with another part of the instruction.

36. Define Inter segment Indirect addressing mode:It replaces the contents of IP and CS with the contents of two consecutive words in

memory that are referenced by using any of the data related addressing modes exceptimmediate and register modes.

37. What is the use of PUSHF instruction used in 8086 ?It pushes the flag register contents to the top of the stack. No flags are affected.

38. Define XLAT instruction used in 8086.It translates a byte in AL using a table in memory. The offset address is calculated

by adding the 8 bit contents of the AL register and the contents of BX register. BXregister contains the starting offset address of the Lookup table. After execution ,corresponding data memory contents of the lookup table are loaded into the AL register.

39. What is DAS instruction ?DAS : Decimal Adjust After Subtraction

This instruction converts the binary result of a SUB or SBB instruction inAL to Packed BCD format. It operates only on AL Register.

40. What is Packed BCD Format?Packed BCD Format: Packed BCD Numbers are stored in two digits to a byte, in

4 bit groups referred to as nibbles. ALU is capable of performing only binary addition andsubtraction, but by adjusting the sum or difference the correct result in packed BCDformat.

41.What is the value of ‘AX’ after executing following instructions?MOV AH,00MOV AL,’7’ADD AL,’3’AAA

Ans : AX= 0100H

42. What is difference between DIV and IDIV instruction in 8086 ?DIV : It operates only on unsigned number.IDIV : It operates only on signed numbers.

43. Write about the following instruction : MOV CS:[BX], DLMOV CS:[BX],DL - It copies a byte from DL Register. Effective Address for

the memory location is contained in the BX Register. Normally an effective address inBX will be added to the data segment base in DS to produce the physical memoryaddress. In this instruction CS: indicates that we want the BIU to add the effectiveaddress to the code segment base in CS to produce the physical address.

content of(BX+(CS) * 1610) = (DL)

44. What is Programmed I/O ?Programmed I/O : It consists of continually examining the status of an Interface

and performing an I/O operation with the Interface when its status indicates that it hasdata to be input or its data- out buffer register is ready to receive data from the CPU.

45. What is the use of Directives in 8086 ?Directives in 8086 give directions to the assembler during the assembly process

but are not translated into machine instruction.

46. What is AAS instruction in 8086 ?AAS: Adjust Result of ASCII SubtractionThis instruction adjusts the binary result of SUB or SBB instruction.

47. What is Unpacked BCD Format?Unpacked BCD Format: In Unpacked BCD, there is only one digit per byte and

because of this, unpacked multiplication and division can be done. Binary operations acton single bytes and the results are adjusted. For Division, the adjustment is done before thebinary division.

48. What is the value of AL after executing the following instructions.MOV AL,35HADD AL,49H

DAA

Ans : AL= 84

49. Define Segment Override Prefix.Segment Override Prefix : To permit exceptions to the Segment Register usage, a

special one byte instruction called a segment override prefix is available . It is ofthe form :

X X X X X X X XMod REG R/M

50. Write the difference between CBW and CWD instruction in 8086.CBW : Convert a byte to a word, sign extend AL Register into a AH Register.CWD : Convert a word to a double word ,sign extend the AX Register into the

DX Register.

51. Write about the following instruction : LES CX, [3483H]Copy the contents of memory at the displacement of 3483H in DS to CL,

contents of 3484H in DS to CH, and copy the contents of memory at displacementof 3485H and 3486H in DS to ES Register.

52. What is the output modes used in 8279?8279 provides two output modes for selecting the display options.1.Display Scan

In this mode, 8279 provides 8 or 16 character-multiplexed displays thosecan be organized as dual 4-bit or single 8-bit display units.2.Display Entry

8279 allows options for data entry on the displays. The display data isentered for display from the right side or from the left side.

53. What are the modes used in keyboard modes?1. Scanned Keyboard mode with 2 Key Lockout.2. Scanned Keyboard with N-key Rollover.3. Scanned Keyboard special Error Mode.4. Sensor Matrix Mode.

54. What are the modes used in display modes?1. Left Entry mode

In the left entry mode, the data is entered from the left side of the displayunit..

2. Right Entry ModeIn the right entry mode, the first entry to be displayed is entered on therightmost display.

55. What is the use of modem control unit in 8251?The modem control unit handles the modem handshake signals to coordinate the

communication between the modem and the USART.

Part B

1. Explain the instruction set with example?2. Name the different Addressing modes used in 8086 instruction set and explain about

each one with suitable example?3. Describe the difference between the instructions MOV AX, 2437H and MOV

AX,[2437H].

Unit – IVPart A

1. What are the basic modes of operation of 8255?There are two basic modes of operation of 8255, viz.

1. I/O mode.3. BSR mode.

In I/O mode, the 8255 ports work as programmable I/O ports, whileIn BSR mode only port C (PC0-PC7) can be used to set or reset its individual

port bits. Under the IO mode of operation, further there are three modes ofoperation of 8255, So as to support different types of applications, viz. mode 0, mode 1 and

mode 2. Mode 0 - Basic I/O modeMode 1 - Strobed I/O modeMode 2 - Strobed bi-directional I/O

2. Write the features of mode 0 in 8255?1. Two 8-bit ports (port A and port B) and two 4-bit ports (port C upper and lower)are available. The two 4-bit ports can be combined used as a third 8-bit port.2. Any port can be used as an input or output port.3.Output ports are latched. Input ports are not latched.4. A maximum of four ports are available so that overall 16 I/Oconfigurations are possible.

3. What are the features used mode 1 in 8255?Two groups – group A and group B are available for strobed data transfer.

1. Each group contains one 8-bit data I/O port and one 4-bit control/data port.2. The 8-bit data port can be either used as input or output port. The

inputs and outputs both are latched.

3. Out of 8-bit port C, PC0-PC2 is used to generate control signals forport B and

PC3=PC5 are used to generate control signals for port A. The lines PC6,PC7 may be used as independent data lines.

4. What are the features used mode 2 in 8255?The single 8-bit port in-group A is available.

1. The 8-bit port is bi-directional and additionally a 5-bit control port isavailable.2. Three I/O lines are available at port C, viz PC2-PC0.3. Inputs and outputs are both latched.4. The 5-bit control port C (PC3=PC7) is used for generating/accepting

handshake signals for the 8-bit data transfer on port A.5.What is the need for interrupt controller?

The interrupt controller is employed to expand the interrupt inputs. It can handlethe interrupt request from various devices and allow one by one to the processor.

6. List some of the features of INTEL 8259 (Programmable Interrupt Controller)1. It manage eight interrupt request2. The interrupt vector addresses are programmable.3. The priorities of interrupts are programmable.4. The interrupt can be masked or unmasked individually.

7. What is a programmable peripheral device ?If the functions performed by a peripheral device can be altered or changed by a

program instruction then the peripheral device is called programmable device. Usually theprogrammable devices will have control registers. The device can be programmed bysending control word in the prescribed format to the control register.

8. What is synchronous data transfer scheme?For synchronous data transfer scheme, the processor does not check the readiness

of the device after a command have been issued for read/write operation. Inthis scheme the processor will request the device to get ready and then read/W1.iteto the device immediately after the request. In some synchronous schemes a smalldelay is allowed after the request.

9. What is asynchronous data transfer scheme?In asynchronous data transfer scheme, first the processor sends a request to

the device for read/write operation. Then the processor keeps on polling the status ofthe device. Once the device is ready, the processor executes a data transfer instruction tocomplete the process.

10. Explain the working of a handshake output portIn handshake output operation, the processor will load a data to port. When the

port receives the data, it will inform the output device to collect the data. Once theoutput device accepts the data, the port will inform the processor that it is empty. Now

the processor can load another data to port and the above process is repeated.

11.What are the internal devices of 8255 ?The internal devices of 8255 are port-A, port-B and port-C. The ports can be

programmed for either input or output function in different operating modes.

12. How DMA is initiated?When the I/O device needs a DMA transfer, it will send a DMA request

signal to DMA controller. The DMA controller in turn sends a HOLD request to theprocessor. When the processor receives a HOLD request, it will drive its tri-stated pinsto high impedance state at the end of current instruction execution and send anacknowledge signal to DMA controller. Now the DMA controller will perform DMAtransfer.

13.What is Block and Demand transfer mode DMA?In Block transfer mode, the DMA controller will transfer a block of data and

relieve the bus for processor. After sometime another block of data is transferred byDMA and so on.In Demand transfer mode the DMA controller will complete the entiredata transfer at a stretch and then relieve the bus to processor.

14. What is USART?The device which can be programmed to perform Synchronous or Asynchronous

serial communication is called USART (Universal Synchronous Asynchronous ReceiverTransmitter). The INTEL 8251Ais an example of USART.

15. What are the functions performed by INTEL 8251A?The INTEL 825lA is used for converting parallel data to serial or vice versa. The

data transmission or reception can be either asynchronously or synchronously. The 8251Acan be used to interface MODEM and establish serial communication through MODEMover telephone lines.

16. What is an Interrupt?Interrupt is a signal send by an external device to the processor so as to request

the processor to perform a particular task or work.

17. What are the control words of 8251A and what are its functions ?The control words of 8251A are Mode word and Command word. The mode

word informs 8251 about the baud rate, character length, parity and stop bits. Thecommand word can be send to enable the data transmission and reception.

18. What are the information that can be obtained from the status word of 8251 ?The status word can be read by the CPU to check the readiness of the transmitter

or receiver and to check the character synchronization in synchronous reception. It alsoprovides information regarding various errors in the data received. The various errorconditions that can be checked from the status word are parity error, overrun errorand framing error.

19. What are the tasks involved in keyboard interface?The task involved in keyboard interfacing are sensing a key actuation,

Debouncing the key and Generating key codes (Decoding the key). These task areperformed software if the keyboard is interfaced through ports and they areperformed by hardware if the keyboard is interfaced through 8279.

20. How a keyboard matrix is formed in keyboard interface using 8279?The return lines, RLo to RL7 of 8279 are used to form the columns of keyboard

matrix. In decoded scan the scan lines SLo to SL3 of 8279 are used to form the rowsof keyboard matrix. In encoded scan mode, the output lines of external decoder areused as rows of keyboard matrix.

21. What is scanning in keyboard and what is scan time?The process of sending a zero to each row of a keyboard matrix and reading the

columns for key actuation is called scanning. The scan timeis the time taken by the processor to scan all the rows one by one starting fromfirst row and coming back to the first row again.

22. What is scanning in display and what is the scan time?In display devices, the process of sending display codes to 7 -segment LEDs to

display the LEDs one by one is called scanning ( or multiplexed display). The scantime is the time taken to display all the 7-segment LEDs one by one, starting from firstLED and coming back to the first LED again.

23. What is settling or conversion time in DAC?The time taken by the DAC to convert a given digital data to corresponding analog

signal is called conversion time.

24. What are the different types of ADC?The different types of ADC are successive approximation ADC, counter type

ADC flash type ADC, integrator converters and voltage- to-frequency converters.

25. Write a short note on INTEL 8255?The INTEL 8255 is a I/O port device consisting of 3 numbers of 8 -bit parallel I/O

ports. The ports can be programmed to function either as a input port or as a output port indifferent operating modes. It requires 4 internal addresses and has one logic LOW chipselect pin.

26.What are the steps required to get data from keyboard?i) Detect a key pressii) Debounce the key press

ii) Encode it27.What is key bouncing?

Mechanical switches are used as keys in most of the keyboards. When a key ispressed the contacts bounce back and forth and settle down only after a small timedelay (about 20 ms). Even through a key is actuated once, it will appear to have beenactuated several times. This problem is called key bouncing

28.What is meant by keyboard debouncing?Key bouncing may cause multiple entries made for the same key. To overcome this

problem after a key press is sensed the device is made to wait for few milliseconds. Thenthe key is checked again to ensure it is still pressed. If it is still pressed it is taken asa valid key press. This process is called keyboard debouncing

29. List the major sections of the 8279 keyboard/display interfacei)Keyboard sectionii) Scan Sectioniii)Display section

iv) CPU interface section

Part B

1. Draw and explain the internal block diagram for 8253.2. Draw control bit format of 8255 for BSR mode. Illustrate an example, where it can be

used3. Specify handshaking signals and their functions if port A of 8255 is set-up B as out-

put port in mode 1.4. Explain mode 0 and mode 1 of 82535. Write a short note on 8251.6. Write a short note on 8253.7. Write a short note on 8257.8. Write a short note on 8259.9. Write a short note on 8279.10. Write a short note on bus contention11. Specify handshaking signals and their functions if port A of 8255 is set-up as out-put

port in mode 1.12. Specify handshaking signals and their functions if port A of 8255 is set-up as input port

in mode 1.13. Explain mode 0 and mode 1 of 825314. With neat diagram explain how the memory is interfaced to 8086 as odd and even page.

ii) Write an 8086 subroutine to test a system in address 00200H- 07FFFH.15. With neat sketch explain the functions of 8255 PPI.16. With neat sketch explain the function of DMA contoller.17. With neat sketch explain the function of Programmable Interrupt Controller.18. With neat sketch explain the function of Keyboard and display controller.19. With neat sketch explain the function of A/D converter.

20. With neat sketch explain the function of D/A converter.

Unit – VPart A

1. Basic concepts in memory interfacingThe primary function of memory interfacing is that the microprocessor should

be able to read from and write into a given register of a memory chip. To perform theseoperations the microprocessor should

• Be able to select the chip• Identify the register• Enable the appropriate buffer

2. List the components of microprocessor (single board microcomputer) based systemThe microprocessor based system consist of microprocessor as CPU,

semiconductor memories like EPROM and RAM, input device, output device andinterfacing devices.

3. Why interfacing is needed for 1/0 devices?Generally I/O devices are slow devices. Therefore the speed of I/O devices does

not match with the speed of microprocessor. And so an interface is provided betweensystem bus and I/O devices.

4.What does memory-mapping mean?The memory mapping is the process of interfacing memories to

microprocessor and allocating addresses to each memory locations.

5.What is interrupt 1/0?If the 1/0 device initiate the data transfer through interrupt then the 1/0 is called

interrupt driven 1/0.

6. Why EPROM is mapped at the beginning of memory space in 8085 system?In 8085 microprocessor, after a reset, the program counter will have 0000H

address. If the monitor program is stored from this address then after a reset, it willbe executed automatically. The monitor program is a permanent program and stored inEPROM memory. If EPROM memory is mapped at the beginning of memory space, i.e.,at 0000H, then the monitor program will be executed automatically after a reset.

7. What is the need for Port?The I/O devices are generally slow devices and their timing characteristics do not

match with processor timings. Hence the I/O devices are connected to system bus throughthe ports.

8.What is a port?

The port is a buffered I/O, which is used to hold the data transmitted from themicroprocessor to I/O device or vice-versa.

9.What is the drawback in memory mapped I/0?When I/O devices are memory mapped, some of the addresses are allotted to I/O

devices and so the full address space cannot be used for addressing memory (i.e., physicalmemory address space will be reduced). Hence memory mapping is useful only for smallsystems, where the memory requirement is less.

Part B

1. Explain the i/o mapped i/o addressing scheme.2. Explain the memory mapped i/o addressing scheme.3. Draw a diagram to interface a 4K ROM and a 2K RAM consecutively with

microprocessor 8085, starting with ROM interfacing at address 0000 H. Explain.4. Draw a diagram to interface a 6K ROM and a 2K RAM consecutively with

microprocessor 8085, starting with ROM interfacing at address 8000 H.5. Interface a 2K ROM with microprocessor 8085, starting with ROM interfacing at

address 0000 H.6. Interface a 8K RAM consecutively with microprocessor 8085, starting with ROM

interfacing at address 8000 H.7. Draw a diagram to interface a 2 chips of 8K ROM and 2 chips of 8K RAM

consecutively with microprocessor 8085.

B.E. ELECTRONICS AND COMMUNICATION ENGINEERINGEC331 - MICROPROCESSOR AND ITS APPLICATIONS

Time: 3hrs Max Marks: 100Answer all Questions

PART - A (10 x 2 = 20 Marks)1. State the function of HOLD pin in 8085.2. Write 8085 assembly language instructions to store the contents of the Flag Register inmemory location 2000H.3. Explain DJNZ instructions of Intel 8031 Micro controller.4. Determine the contents of the accumulator after the execution of the following programsegments

MOV A,# 3CHMOV R4,66H

ANL A,R4

5.State the function of Direction flag in 80866. Describe the difference between the instructions MOV AX, 2437H and MOV AX,[2437H]7. How does Port C of 8255 differ from ports A and B.8. Explain the function of in-service register in 8259 programmable interrupt controller.9. Draw a circuit to interface a stepper motor winding to a microprocessor port bit usingpower MOSFET10. Why Gray code is used in Shaft angle encoder.

PART - B (5 x 16 = 80 Marks)

11.a) Draw the circuit diagram of an 8085 system having a 4 KB EPROM and 8 KB RAMICs. The starting address of the EPROM is 0000H and that of RAM is 8000H. The addressdecoder circuits should be clearly shown.(OR)11.b) Write a subprogram using 8085 assembly language to multiply two 8 bit binarynumbers by repeated addition.

12.a)i) Determine the value of the accumulator after the execution of instructions A:,B:, C:and D:MOV 40H , #88HMOV R0 , #40HA: MOV A , R0B: MOV A, @R0C: MOV A, 40H

D: MOV A, #40Hii) With neat diagram explain the timer / counter functions in 8051 Micro Controller.(OR)12.b) Using ports P0 and P1 of 8051 micro controller design an 8 digit 7 segmentmultiplexed display system. Use suitable driver circuit and give flowchart for the softwareinvolved.

13.a)i) With neat diagram explain how the memory is interfaced to 8086 as odd and evenpage.ii) Write an 8086 subroutine to test a system in address 00200H- 07FFFH.(OR)13.b) Describe in detail the memory management functions in Intel 80286/80386 Processor

14.a) With block diagram describe the working of a DMA controller.(OR)14.b) With a neat diagram describe how the DAC 1408 can be interfaced to the microcontroller 8031.Using this hardware write 8031 assembly language to generate a Triangularwave.

15.a) Using DC servomotor and shaft angle encoder as sensor design a Microprocessorbased position control system.(OR)15.b) Describe how a closed loop microprocessor based process control system can beimplemented by using digital PID control algorithm.

Anna UniversityBE - ELECTRONICS AND COMMUNICATION

EC1303-Microprocessor and its Applications(Common to B.E (Part-time) Fourth Semester Regulation 2005)

Time:Three hours Maximum:100 marks

Answer ALL questionsPART A –(2*10=20marks)

1. What are the classifications of instruction set according to word size?2. Name the modes available in 8255 A control word format.3. What are the methods used for communication in 8055?4. List the control words of RS-232 C.5. What are the segment registers of 8086?6. Name any four flags of 8086.7. What are the addressing modes of 8051?8. List the interrupts in 8051.9. What are the functions of assembler and linker in 8051?10. What are the commonly used ADC’s and DAC.

PART-B(16x5=80)

11.(a) Draw and explain the pin details of 8085A briefly. [Marks 16]Or(b)(i) What are the flags affected by ALU in 8085? Explain briefly. [Marks 10](ii) Draw the schematic diagram of memory interfacing in 8085. [Marks 6]

12.(a)(i)Draw and explain the control word format of 8255A for ADCoperation. [Marks 8 ](ii)Give a brief note on the following [Marks 8 ](1) 8251 I/O device(2) GPIB BusOr(b) Draw and explain the logic diagram of 8279 [Marks 16]

13.(a)(i) Draw the pin diagram of 8086 CPU with its control signals. [Marks 8 ](ii) Explain how an interrupt is responded by 8086 CPU. [Marks 8 ]Or(b)(i) Write a program in 8086 to find an average between two temperatures. [Marks 8 ](ii) Describe data transfer instructions of 8086 CPU. [Marks 8 ]

14.(a)(i) Explain the features of 8051 microcontroller [Marks 6](ii) Draw and explain the connection diagrams of 8051 with external ROM. [Marks 10]Or(b)(i) Explain the basic structure of assembly language program of 8051. [Marks 8 ](ii) Explain the memory organization of 8051. [Marks 8 ]

15.(a)(i)List and explain conditional jump instructions of 8051 [Marks 6](ii) Draw and explain briefly the connection diagram of ADC with peripheral device withone example. [Marks 10]Or(b)(i) What are the features of LCD? How it is interfaced with 8051? [Marks 2+6](ii) Write a program in 8051 to transfer letter ‘A’ serially at 4800 bandrate,continuously .[Marks 8 ]

B.E. ELECTRONICS AND COMMUNICATION ENGINEERING

EC331 - MICROPROCESSOR AND ITS APPLICATIONS

Time: 3hrs Max Marks: 100

Answer all Questions

PART - A (10 x 2 = 20 Marks)

1. State the function of HOLD pin in 8085.

2. Write 8085 assembly language instructions to store the contents of the Flag Register inmemory location 2000H.

3. Explain DJNZ instructions of Intel 8031 Micro controller.

4. Determine the contents of the accumulator after the execution of the following programsegments

MOV A,# 3CH

MOV R4,66H

ANL A,R4

5. State the function of Direction flag in 8086

6. Describe the difference between the instructions MOV AX, 2437H and MOV AX, [2437H]

7. How does Port C of 8255 differ from ports A and B.

8. Explain the function of in-service register in 8259 programmable interrupt controller.

9. Draw a circuit to interface a stepper motor winding to a microprocessor port bit using powerMOSFET

10. Why Gray code is used in Shaft angle encoder.

PART - B (5 x 16 = 80 Marks)

11.a) Draw the circuit diagram of an 8085 system having a 4 KB EPROM and 8 KB RAM ICs.The starting address of the EPROM is 0000H and that of RAM is 8000H. The address decodercircuits should be clearly shown.

(OR)

11.b) Write a subprogram using 8085 assembly language to multiply two 8 bit binary numbersby repeated addition.

12.a)i) Determine the value of the accumulator after the execution of instructions A:,B:, C: andD:

MOV 40H , #88H

MOV R0 , #40H

A: MOV A , R0

B: MOV A, @R0

C: MOV A, 40H

D: MOV A, #40H

ii) With neat diagram explain the timer / counter functions in 8051 Micro Controller.

(OR)

12.b) Using ports P0 and P1 of 8051 micro controller design an 8 digit 7 segment multiplexeddisplay system. Use suitable driver circuit and give flowchart for the software involved.

13.a)i) With neat diagram explain how the memory is interfaced to 8086 as odd and even page.

ii) Write an 8086 subroutine to test a system in address 00200H- 07FFFH.

(OR)

13.b) Describe in detail the memory management functions in Intel 80286/80386 Processor

14.a) With block diagram describe the working of a DMA controller.

(OR)

14.b) With a neat diagram describe how the DAC 1408 can be interfaced to the micro controller

8031.Using this hardware write 8031 assembly language to generate a Triangular wave.

15.a) Using DC servomotor and shaft angle encoder as sensor design a Microprocessor basedposition control system.

(OR)

15.b) Describe how a closed loop microprocessor based process control system can beimplemented by using digital PID control algorithm.

Anna UniversityBE - ELECTRONICS AND COMMUNICATION

EC1303-Microprocessor and its Applications

(Common to B.E (Part-time) Fourth Semester Regulation 2005)

Time:Three hours Maximum:100 marks

Answer ALL questions

PART A –(2*10=20marks)

1. What are the classifications of instruction set according to word size?

2. Name the modes available in 8255 A control word format.

3. What are the methods used for communication in 8055?

4. List the control words of RS-232 C.

5. What are the segment registers of 8086?

6. Name any four flags of 8086.

7. What are the addressing modes of 8051?

8. List the interrupts in 8051.

9. What are the functions of assembler and linker in 8051?

10. What are the commonly used ADC’s and DAC.

PART-B(16x5=80)

11.(a) Draw and explain the pin details of 8085A briefly. [Marks 16]

Or

(b)(i) What are the flags affected by ALU in 8085? Explain briefly. [Marks 10]

(ii) Draw the schematic diagram of memory interfacing in 8085. [Marks 6]

12.(a)(i)Draw and explain the control word format of 8255A for ADC

operation. [Marks 8 ]

(ii)Give a brief note on the following [Marks 8 ]

(1) 8251 I/O device

(2) GPIB Bus

Or

(b) Draw and explain the logic diagram of 8279 [Marks 16]

13.(a)(i) Draw the pin diagram of 8086 CPU with its control signals. [Marks 8 ]

(ii) Explain how an interrupt is responded by 8086 CPU. [Marks 8 ]

Or

(b)(i) Write a program in 8086 to find an average between two

temperatures. [Marks 8 ]

(ii) Describe data transfer instructions of 8086 CPU. [Marks 8 ]

14.(a)(i) Explain the features of 8051 microcontroller [Marks 6]

(ii) Draw and explain the connection diagrams of 8051 with

external ROM. [Marks 10]

Or

(b)(i) Explain the basic structure of assembly language program of

8051. [Marks 8 ]

(ii) Explain the memory organization of 8051. [Marks 8 ]

15.(a)(i)List and explain conditional jump instructions of 8051 [Marks 6]

(ii) Draw and explain briefly the connection diagram of ADC with peripheral device with one

example. [Marks 10]

Or

(b)(i) What are the features of LCD? How it is interfaced with 8051? [Marks 2+6]

(ii) Write a program in 8051 to transfer letter ‘A’ serially at 4800

bandrate,continuously . [Marks 8 ]