RA
Code No: RR310501
III B.Tech I Semester(R05) Supplementary Examinations, June 2009 INTERFACING THROUGH MICROPROCESSORS (Common to Computer Science & Engineering, Information Technology and Computer Science & Systems Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) What are segment registers? How to load segment registers? Explain segment override prefix with example. (b) What are vectored interrupts? Explain hardware and software interrupts in 8086. [8+8] 2. (a) Draw the programming model of 8086, containing 8 bit, 16 bit and 32 bit registers and also list the general purpose and multipurpose registers of 8086. [8+8] (b) Explain the operation of 8086 in real mode and protected mode of memory addressing. 3. Develop an 8086 assembly language program which has a macro with one parameter called TEMP. The macro reads the keyboard using INT21H and places the ASCII code of the key read in TEMP. The macro defined above is used thrice to read the keyboard thrice and store the ASCII codes in three consecutive memory locations. [16] 4. (a) What kind of I/O interface does a 8255 implement, and how many I/O lines are available on the 8255 (b) What is the function of the port B lines of the 8255 when port A configured for mode 2 Operations [6+4+6] (c) Explain about maximum mode interrupt interface 5. (a) What is minimum no. of bus cycles that can occur between the time an interrupt request is recognized and the first instruction in the interrupt routine is fetched. Draw the bys cycles. (b) Write an instruction sequence that will cause the priority of an 8259, whose even address is 08A0, to be IR4, IR5, IR6, IR7, IR0, IR1, IR2, IR3. Solve this twice, once assuming that the highest priority is currently IR0 and once assuming that it is IR3. [6+10] 6. (a) Design a circuit to activate a actuator, based on a bit combination given by eight switches interfaced to a microprocessor (b) Design a interface circuit to feed numbers 0-9 through a linearly encoded switches and to display the number on a seven segment LED through a microprocessor [8+8] 7. Explain with a block diagram how a stepper motor can be interfaced to a microprocessor and explain its working. [16] 8. (a) Write a program sequence which initializes the mode register and gives a command to enable the transmitter and begin an asynchronous transmission of 7-bit characters followed by an even parity bit and 2 stop bits. Explain the program. (b) Explain the following terms: i. Simplex, half-duplex and full duplex. ii. baud rate. iii. framing error. iv. Over run error. [8+8] ?????