Final Examination Solutions Fall 2008

PwnHero Final Examination COE538-Microprocessor Systems December 4, 2008 Name: _______________________________________ Student #: ______________ Section #: ______ Time limit: 3 hours Examiners: V. Geurkov, A. Ye Notes: a) Closed book. b) No questions during exam period. State any assumptions. c) Answer neatly all questions in the space provided. Unclear answers will not be accepted. d) For each question, show the process that is used to derive the answer. e) Circle your professor’s name and hand in these sheets. 1. Short Answer Questions: [1 mark each] a) What register is used to keep track of the address of the next instruction to be executed? Program counter - PC b) Convert hex decimal number 7AC9 into 16-bit binary representation. 7AC916 = 0111 1010 1100 10012 c) How many memory chips are required to build a 8MB, 16-bit wide memory system using 256K × 1 SRAM chips. 8MB = 23 × 220 × 23 = 226 bits 256K × 1 = 28 × 210 × 20 = 218 bits 226 / 218 = 28 = 256 chips d) List an advantage for using interrupts to handle data inputs and outputs? Interrupts provide immediate response to events; microcontroller is not tied with the polling of flags. e) List the instruction used to enable interrupts and the instruction used to disable interrupts on 68HC11. CLI – clear interrupt mask SEI – set interrupt mask f) What value should be written into TCTL1 to toggle the voltage on the PA5 pin (see the HC11 block diagram) on successful output compares? XX01 XXXX PwnHero.com