R5311901-microprocessors And Interfacing

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Code No: R5311901

III B.Tech I Semester(R05) Supplementary Examinations, May 2009 MICROPROCESSORS AND INTERFACING (Common to Electronics & Computer Engineering, Instrumentation and Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Explain the architecture of 8085 microprocessor with a neat block diagram. (b) What is an instruction? Explain various instruction formats with examples. [10+6] 2. (a) Discuss various branch instruction of 8086 microprocessor, that are useful for relocation? (b) Using a do-while construct, develop a sequence of 8086 instructions that reads a character string from the keyboard and after pressing the enter key the character string is to be displayed again. [8+8] 3. (a) Write a 8086 ALP to find Y where Y = x2 +2x+5 and X is between 0 and 9. (b) Write a program to generate delay of 20sec by calling the procedure for 0.05 sec. Delay (if the microprocessor frequency is 6MHz). [8+8] 4. What are the functions of a DMA controller? Explain the various DMA modes. Describe in brief the steps that take place during a DMA Operation. [16] 5. (a) Draw the block diagram of 8255 and explain each block. (b) Interface an 8255 with 8086 to work as an I/O port. Initialize Port-A as output port, Port-B as input port and Port-C as output port. All ports are operated in mode-0. PortA address should be 0740H. Write a program to sense switch positions SW0 to SW7 connected at Port-B. The sensed pattern is to be displayed on Port-A, to which 8 LEDs are connected, while the Port-C lower displays number of ON switches out of the total 8 switches. [8+8] 6. (a) What are the advantages of using 8259? (b) Draw and explain the interfacing of cascaded 8259s with 8086.

[8+8]

7. (a) Explain the following MODEM control lines: i. ii. iii. iv.

DSR DTR RTS CTS.

(b) Explain the operation of 8251 a neat block diagram.

[8+8]

8. Draw and discuss the formats and bit definitions of the following SFR’s in 8051 microcontroller. [4×4] (a) PSW (b) IE (c) SCON (d) TMOD. ?????

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Code No: R5311901

III B.Tech I Semester(R05) Supplementary Examinations, May 2009 MICROPROCESSORS AND INTERFACING (Common to Electronics & Computer Engineering, Instrumentation and Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Why the internal architecture of 8086 is divided into two functional units. Explain the functions of each unit with neat block diagram of the 8086 architecture. [16] 2. The register contents of 8086 is given below. CS=5000H, DS=8000H, SS=9000H, ES=7000H, SI=1000H, DI=2000H, BP=0008H, SP=0002H, AX=0000H, BX=5200H, CX=8000H, DX=2800H Calculate the effective address and physical address for different addressing modes of 8086 microprocessor by assuming suitable Instructions. [16] 3. (a) Write the sequence of statements that declare the word named NWORD and the FAR label EXTMOD as being external and the variable LWORD and the label LOCMOD as being local and accessible by other source modules? (b) How could you use the TEST instruction (or a sequence of TEST instructions) to see if bits zero and four in the AL register are both set to one? How would the TEST instruction be used to see if either bit is set? How could the TEST instruction be used to see if neither bit is set? [8+8] 4. The I/O circuitry in an 8086 based system consists of five I/O devices with one status signal for each device. Design the required hardware providing two address locations to each device, one for status and other for data. In the range 0F00H to 0FOFH. Write an instruction sequence to test the status of each device and store it. [16] 5. Explain why 8255 ports are divided into two groups? Discuss how these groups are controlled in different modes of operation? Explain different control signals and their associated pins for bi-directional I/O mode of operation. [16] 6. (a) What are software interrupts? How 8086 responds to software interrupts? (b) Briefly describe the conditions, which cause the 8086 to perform each of the following types of interrupts: Type-0, Type-1, Type-2, Type-3 and Type-4. [8+8] 7. (a) Discuss the mode instruction format of 8251 for synchronous and asynchronous mode of operation. (b) Discuss overrun error and framing error with reference to 8251. [8+8] 8. (a) Draw and discuss the formats and bit definitions of the following SFR’s in 8051 microcontroller. i. SCON ii. TCON (b) Discuss the following signal descriptions: [8+8] i. ALE / PROG ii. (EA)’ / VP P iii. (PSEN)’ iv. RXD. ?????

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Code No: R5311901

III B.Tech I Semester(R05) Supplementary Examinations, May 2009 MICROPROCESSORS AND INTERFACING (Common to Electronics & Computer Engineering, Instrumentation and Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Explain in detail various addressing modes used in 8085 Microprocessor with examples. (b) Explain the following pins of 8085 Microprocessor. i. ADO -AD7 ii. IO/M iii. SO , S1 , S2 iv. INTR. 2. (a) Write a program to move a block of memory with out over lapping. (b) Discuss the following instructions. i. ADC ii. AAS iii. IMUL iv. CBW.

[8+8]

[8+8]

3. Write the sequence of instructions in 8086 assembly language to perform the following: (a) Multiply two 32 bit numbers. (b) Shift right a 16 bit number by 3 bits. (c) Invert right most four bits of AL. 4. (a) (b) (c) (d)

[6+4+6]

Why it is important that main memory support efficient block transfers? Why is DRAM denser than SRAM? Be explicit. What does the term ‘refresh’ mean with respect to DRAM? An SRAM has address pins A0-A17, and Data pins D0-D15. What is the total number of bits stored in this device? [4+4+4+4]

5. Write assembly language programs to rotate a 100 teeth, 4 phase stepper motor as specified below: (a) Six rotations clockwise and then six rotations anti-clockwise. (b) Rotate through angle 1350 in 2 seconds. (c) Rotate the shaft at a speed of 10 rotations per minute. 6. (a) Draw the block diagram of 8259 and explain each block. (b) Explain how IRET instruction is executed.

[5+5+6] [8+8]

7. (a) Define the term MODEM and explain why a MODEM is required to send digital data over standard switched phone-lines. (b) Show the bit pattern for the mode word and the command word that must be sent to an 8251 to initialize the device as follows: Baud rate factor of 64, 7-bits per character, even parity, 1 stop bit, transmit interrupt enabled, DTR and RTS asserted, Error flags reset, No hunt mode, No break character. [8+8] 8. (a) Draw and discuss the formats and bit definitions of the following SFR’s in 8051 microcontroller. i. SCON ii. TCON (b) Discuss the following signal descriptions: [8+8] i. ALE / PROG ii. (EA)’ / VP P iii. (PSEN)’ iv. RXD. ?????

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Code No: R5311901

III B.Tech I Semester(R05) Supplementary Examinations, May 2009 MICROPROCESSORS AND INTERFACING (Common to Electronics & Computer Engineering, Instrumentation and Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) What is PSW in 8085. Explain the contents of PSW. (b) Explain the use of DS, ES registers in 8086. (c) What is extended accumulator? How it is used in MUL and DIV instructions in 8086. [6+4+6] 2. (a) Distinguish between packed BCD and unpacked BCD (b) Explain branch instructions of 8086 with examples.

[4+12]

3. Write an algorithm and assembly program to find the square root of a 16 bit number using shift and subtract method. [16] 4. (a) Draw and discuss the mode set register of 8257? (b) Discuss the priorities of DMA request inputs of 8257? (c) Explain functions of the following signals of 8257? i. ii. iii. iv.

[6+4+6]

ADSTB TC HRQ AEN.

5. (a) Explain the control word format of 8255 in I/O mode and BSR mode. (b) Interface an 8255 with 8086 so as to have Port-A address BCD1H, Port-B address BCD3H, Port-C address BCD5H and Control word register address BCD7H. [8+8] 6. Explain the following interrupts: (a) Divide-by-zero interrupt (b) Single step interrupt (c) Break point interrupt (d) Overflow interrupt.

[4 × 4]

7. (a) Draw and explain Command and Mode word formats of 8251. (b) Explain the interfacing of 8251 with 8086 in memory mapped I/O mode.

[8+8]

8. (a) Explain various operation modes of Timers. (b) Write an 8051 ALP to transfer the message “LBRCE” serially at 4800 baud, 8-bits, 2 stop bits [8+8] ?????