Midterm Solutions Fall 2007

PwnHero October 24th, 2007 COE 538 Midterm Name: _____________________________ Student #: __________________ Time: 50 min. First Last Notes: 1. Close book 2. Write the answers in the space provided 3. Show the process that is used to derive your answers 1. Short Answer Questions [4 marks] a) What is the last instruction in an interrupt service routine? [1 mark] RTI b) What is the last instruction in a subroutine? [1 mark] RTS c) A matrix with N rows and M columns is stored in memory using column major format. Each entry in the matrix is one byte in size. Write down the formula (not a program) to calculate the memory address of the item stored on the i th row and the j th column of the matrix? [2 marks] Address of the (I,j)th element = (j x N) + i + address of the first element of the matrix 2. Write an instruction sequence to copy the 5th, 6th, and 7th element of an array whose first element is located at $6000 to the 2nd, 3rd, and 4th element of another array whose first element is located at $6100. Your program should contain no more than 10 instructions. [5 marks] ldx #$6000 label ldaa x,4 staa x,101 inx cpx #$6003 bne label swi 3. Assume that the VRH and VRL inputs to the 68HC11 A/D converter are 5V and 0V, respectively. What is the corresponding voltage value for the conversion result of 67 (show the computation process)? [3 marks] voltage value = 67 x 5 / 255 = 1.31 V PwnHero.com