SUB: MicroprocessorsSUB CODE: EC45

CHAPTER 1: Architecture and operation.

1. Give a general block diagram of a microprocessor based system. Explain briefly the various blocks of the system. Give some examples of the types of devices used for each block.

2. What is a microprocessor? Sketch and explain the various pins of 8085.3. Sketch and explain the signal diagram of 8085.4. Explain the operation of 8085 signals: READY, S1 & S0, HOLD & HLDA and ALE.5. Explain the architecture of 8085 with the help of its internal block schematic.6. Write the flag register and explain each of the flags with an example.7. Mention the list of registers of 8085 that are accessible to the programmer.

Explain what each of these registers are generally used for.8. What should be the starting address of ROM for an 8085 microcomputer?

Substantiate your answer.9. Explain the purpose of the following signals of 8085: AD0-AD7, /RESET IN, RESET

OUT, and RST 7.5.10.Explain with schematic diagram how separate address, data signals can be

generated from 8085 common address-data lines.11.Explain the schematic which decodes IO//M, /RD, /WR into two active low

signals /MERD, /MEWR, /IORD and /IOWR.12.List the status signals in 8085. Explain their functions.13.List the control signals in 8085. Explain their functions.14.Explain, how the microprocessor works?15.Explain the operations of microprocessor.16.What are RAM’s and ROM’s? why should both of these be used in an 8085

system?17.Explain the functions of following 8085 registers in Intel 8085: HL, STACK

POINTER, and FLAG REGISTER.

CHAPTER 2: Programming the 8085.

18.Sketch the programming model and explain in detail.19.What are the various addressing modes available in 8085? Explain with

examples.20.Explain the instruction format of 8085 microprocessor with an example.21.How do you classify the instructions of 8085, based on a) Number of bytes b)

Addressing modes? Explain with examples.22.Give two examples for each of the following types of instructions and indicate

what each of these instructions do:

a. Instructions with implied addressing.b. ALU type of instructions.c. Instructions addressing memory indirectly through any register pair.d. Conditional branch instructions.

e. Interrupt related instructions.23.Explain fully the action of the following 8085 instructions: ADC M, STAX D, RLC,

LHLD 9898, and TRAP.24.Explain the following instructions and indicate the flags affected: DAA, DAD D,

XCHG, HALT & MOV M, A.25.Define Instruction cycle, Machine cycle and T-States with examples.26.Explain the following instructions indicating their addressing modes, flags

affected, number and names of machine cycles on the execution of each: XRA A, SUB M, & DCXSP.

27.Draw opcodes fetch machine cycle, memory write machine cycle and I/O read machine cycle and explain.

28.Explain the various steps involved while executing CALL instruction with an example.

29.Explain DAA instruction with example.30.Explain the functions and timing associated with STA and RST instructions.31.Explain the working of CALL address and RET instructions, in terms of machine

cycles.32.Write an ALP for 8085 to multiply two 8-bit numbers. Explain your program with

only comments.33.Write a program in 8085 to convert the binary number stored in location XX20h

to BCD. Store the possible three BCD digits in unpacked manner from location XX50h.

34.What is a stack? On what principle it works? Is it necessary to intialize stack pointer while writing program? Explain with example.

35.Mention the uses of stack. Sketch the content of SP and stack memory after the execution of each of the following instructions in the given order, if SP = 1000h, BC = 2030h and DE = 4050h initially: PUSH B and PUSH D.

36.With suitable programming example clearly explain passing the parameter through registers, through memory and through stack.

37.Explain stack operation in detail.38.Sketch and explain briefly the timing diagram of the instruction MVI A, 32h,

which is stored from address 3000h.39.Draw the timing diagram for the instruction STA 9000h.40.Write an 8085 program to simulate a decimal upcounter to count 00 to 99. Use

delay of 100 msec in between counts. Assume the operating frequency as 2 MHz.

41.What is the use of instruction ORA A? What is the status of CY and AC flags after the execution of this instruction?

42.Write a recursive subroutine named FACT to find factorial of the number in 8085.43.Using JMP, can you call a subroutine? Explain with an example and a

corresponding ALP.44.Write an ALP to count number of 1’s and 0’s present in a hex byte present at

9100h memory location. Store number of 1’s at 9101h and number of 0’s at 9102h.

45.Write an ALP for 8085 processor to separate ODD and EVEN numbers from an array of 16 numbers stored from F100h. Store the EVEN numbers from F120h and ODD numbers from F150h.

46.Write an ALP subroutine to produce a delay of 1 second. Consider the 8085 clocked at 5 MHz.

47.What is a subroutine? How it is useful? Explain the use of stack in CALL and RET instructions.

48.Explain any five logical instructions with their function, addressing modes and flags affected.

NOTE: Any of the instructions can be asked for explanation.One must Cover lab programs also.

CHAPTER 3: Memory Interface

49.Compare the memory mapped I/O with peripheral mapped I/O.50.Interface the following memory to 8085: 51.ROM : 2Kx 8-bit, using 2716, starting address : 0000h52.RAM : 2Kx 8-bit, using 6116, starting address : 8000h53.Use absolute address decoding. Show all the control signals interfacing.54.Design a microcomputer to obtain the following: 4K EPROM, 512 bytes static

RAM, four 8-bit ports. usinga. Standard I/O and linear decoding.b. Full decoding using 3x8 decoder.c. Memory mapped I/O and full decoding.

55.Interface two input ports at addresses FFFOh and FFF1h and two output ports at addresses 9000h and 9001h using memory mapped I/O. Indicate the assumptions made if any.

56.Interface 8K bytes of EPROM & 4K bytes of RAM, 8 I/P devices, 8 O/P devices to a 8085 system in I/O mapped I/O. the memories are provided in 2K bytes ICs. Give the schematic diagram with address data bus demultiplexing, indicate the decoding logic & the address space for each.

57.Differentiate between partial decoding and absolute decoding in case of device (memory I/O) selection. Give an example.

58.Interface 8K byte RAM and 4K byte EPROM to 8085, by absolute decoding using 74LS138 decoder. Give the memory map starting at address 0000h for EPROM.

59.Explain: i) memory mapped I/O, ii) I/O mapped or standard I/O, iii) serial I/O.

CHAPTER 4: Interrupts

60.Explain in detail the interrupt system of 8085.61.Design and explain a scheme to interrupt on INTR of 8085.62.Indicate all the pins of 8085 through which the processor can be interrupted. In

respect of each of these pins describe how the processor obtains the starting address of the interrupt service routine.

63.What is meant by priority interrupts? Explain the operation of different interrupts available in 8085, with the help of circuit diagram.

64.How is the device priority determined in hardware polling? Explain.65.Distinguish between: i) Vectored and non vectored interrupt, ii) Maskable and

non maskable interrupt, iii) Internal and external interrupt, iv) Software and hardware interrupt.

66.Explain interrupt driven I/O technique. How 8085 responds to INTR interrupt?

CHAPTER 5: Interfacing of peripherals (I/Os) and applications.

67. Explain the operation of 8255 PPI chip with its internal block schematic. Explain its mode 0, mode 1 and BSR modes.

68. Write a short note on 8279 keyboard/display interface.69. Which characteristics of an I/O device makes it necessary to interface the device through

DMA? Explain the DMA operation in detail.70. Explain with block diagram the 8253 timer chip and its operation.71. Explain with block diagram the USART 8251 chip and its operation.72. Explain how data can be transferred using 8251 USART at different baud rates. Also discuss

the features available in 8251.73. Explain the features of 8253. Briefly explain its different modes of operation.74. Explain how 8259 communicates with 8085. Explain the different functions available in

priority interrupt controller.75. With the help of functional block diagram, explain the different features available in 8279.76. What are the maximum and minimum frequencies that can be generated using 8155 timer

section when 8085 clock is 3 MHz.77. Explain with diagram serial synchronous and asynchronous data formats of 8251.78. Write a program to transmit 8 bit data through SOD pin starting with MSB. The data is stored

at address 1A00h.79. Write the signals of RS232 port.80. Write an ALP to generate square wave using 8255.81. Write & explain the mode word format, command word format & status word format of

8251.82. Write ALP to intialize 8251 USART and receive data on polled basis given the parameters:

Baud rate factor = 64, Character length = 8 bits, No parity check and 1 stop bit. Assume port address 50h for data and 51h for control/status.

83. Explain the features and operation of DMA controller 8257 with a block schematic.84. Interface an A/D converter to 8085 and write a program to convert the analog input to digital.85. Show how you would interface a keyboard to an 8085 processor using 8255. Write an ALP

to generate a key code for the key pressed.