FinalSummer2009 - 30-07-2009 BILKENT UNIVERSITY Electrical...

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30-07-2009 BILKENT UNIVERSITY Electrical and Electronics Engineering Dept. 2009 Summer Semester EEE212 Microprocessors Final Exam Open TextBook – Calculators Allowed Use comments for readability , otherwise the programs will be partially graded! Duration: 2 hours SOLUTION KEY Q1 (18 points) Q2 (22 points) Q3 (30 points) Q4 (30 points) TOTAL
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1 Q-1) [18 pts] Answer the following questions. Try to make your answers as clear as possible, and not longer than sufficient. a) What is the advantage and disadvantage of serial DACs (DACs giving the output through a single output pin) over parallel DACs (DACs giving the output through multiple parallel output pins)? Write at least one advantage and one disadvantage. Serial DACs use less pins to send the data, which is an advantage in space critical applications. Their disadvantage is that, it takes more time to send the data through a single pin. b) Assume that an 8051 has received a byte of data through the serial port and before copying it to any other location from SBUF, it started to transmit a byte of data with the instruction MOV SBUF,A. In that case, is the received data overwritten? If your answer is yes, what precautions can be taken to prevent this problem when writing your code? If your answer is no, explain why. The data is NOT overwritten, because physically SBUF corresponds to two separate registers. The received byte is placed to one of them, the bytes to transmit are placed to the other. c) Assume that both external data and program memories are connected to an 8051. If there are external data and program memory locations with the same address, how does 8051 decide which one to access? (When does it access the code memory and when does it access the data memory) Also explain why both of the memory units are not enabled at the same time although their addresses are the same. 8051 accesses the data memory when it reads data with the instructions MOV and MOVX. It accesses the program memory when it is fetching instructions or reading data from code memory with the MOVC instruction. Since data memory units are enabled with RD/WR signals and program memory is activated with PSEN signal, they are not activated at the same time. d)
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This note was uploaded on 10/23/2011 for the course ENGINEERIN 102 taught by Professor Pablo during the Spring '11 term at Bilkent University.

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FinalSummer2009 - 30-07-2009 BILKENT UNIVERSITY Electrical...

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