Midterm Solutions Fall 2012

PwnHero October 24th, 2012 COE/BME-538 Midterm Exam Name: _____________________________________ Student #: _______________________ Time: 90 min. Notes: 1. Closed book. 2. Write the answers in the space provided. 3. No question during the exam. State your assumptions. 1. Multiple Choice Questions (encircle the correct answer): [1 mark each] a) What instruction is used to exit a subroutine? i) rtb ii) rtf iii) rti iv) rts v) str b) How many memory locations can the HCS12 access without the expanded memory? i) 65535 ii) 65536 iii) 64000 iv) 32000 v) 32K c) How many address lines are required to access 32K memory locations? i) 15 ii) 16 iii) 32 iv) 64 v) 128K d) Which of the following instructions will swap the contents of registers Y and SP: i) exg y,sp ii) xg ysp iii) tys iv) lds #2 v) staa $3 2. Fill in the underlined spaces and identify the register contents after the execution of the programs below: a) Load Reg.A with $35 and subtract the value $CF located at $1200 from the contents of Reg.A. Then, store the result in the memory location at $1250. Fill in the underlined spaces. [3 marks] org $1500 ldaa #$35 ; load Reg.A with $35 suba $1200 ; subtract the value $CF located at $1200 from Reg.A staa $1250 ; store the result at $1250 swi ; stop Show the contents of Reg.A and CCR after the execution of the program: [3 marks] Reg.A Bit #: 7 6 5 4 3 2 1 0 Contents: 0 1 1 0 0 1 1 0 CCR Bit code: S X H I N Z V C Bit #: 7 6 5 4 3 2 1 0 Contents: x x x x 0 0 0 0 0011 0101 1100 1111 0011 0101 0011 0001 0110 0110 - + PwnHero.com