2) [ 2 marks] Both of the following statements cause the value $0300 to be stored in location $1000, but at different times. Explain the difference.

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1 1) [ 9 marks] Write a sequence of directives for an HCS12 assembly language program that performs all of these tasks, in this order: a) Define an array called Measurements starting from memory location $2000 and initialize it with $20, $78, $25, $18, $02. b) Define a word memory location called Counter and initialize it to zero. c) Reserve the next 12 bytes with the label Username. Do not initialize them. d) Reserve the next 12 words with the label Measurements. Do not initialize them. e) Define a string called Msg and initialize it with please enter your user name:. f) Define a character called CHR and initialize it with space. g) Define a constant value called Led_mask and initialize it with the constant value of binary h) Build a table of ASCII codes of lower-case letters a-z called lower_case_table. i) How many bytes these directives will occupy? What is the last address? 2) [ 2 marks] Both of the following statements cause the value $0300 to be stored in location $1000, but at different times. Explain the difference. org $1000 var DW $0300 and MOVW #$0300,$1000 3) [4 marks] Fill up the first and second columns in the next table with the machine code and the memory locations of the given code. The meaning of what is stored in memory depends on your interpretation. The contents in the table can be seen as instructions, but they can also be seen as ASCII codes for characters. What are these characters? fill column 3. The memory contents can also be seen as signed/unsigned byte or word numbers. Fill up the last two columns in decimal. You can use calculator. Org $800 ABA STAA $09DE LDAA #$02 STAB A,X Memory location Contents ASCII Signed/unsigned byte numbers Signed/Unsigned word numbers ) [5 marks] Determine how the following instructions will affect the CC register bits. Use unaffected, Affected, 0, or 1 ( 1/6)

2 Instruction N Z V C ABX adda #$12 anda #$FF Asld bne dex emul eora inx ldaa 5) [8 marks] For each of the code fragments below, determine which of the 8 simple branches (BPL, BMI, BNE, BEQ, BVC, BVS, BCC, BCS) are taken, not taken, or cannot be determined. Note the Bxx is used to represent a generic branch instruction. Show your work. A) LDAA #$00 D) LDAA #$B3 ROLA B) LDAA #$C0 ADDA #$C0 C) LDAA #$A0 SUBA #$50 T = taken, NT = Not taken, CBD = Cannot Be Determined A B C D BPL BMI BNE BEQ BVC BVS BCC BCS 6) [8 marks] For each of the code fragments below, determine which of the 10 comparison branches (BHI, BHS, BLS, BLO, BGT, BGE, BLE, BLT, BNE, BEQ) are taken, not taken, or cannot be determined. Note the Bxx is used to represent a generic branch instruction. Show your work. A) LDAA #$80 ASRA CMPA #$80 D) LDAA #$27 NEGA CMPA #$27 B) LDAA #$80 CMPA #$80 C) LDAA #$50 COMA CMPA #$B0 ( 2/6)

3 T = taken, NT = Not taken, CBD = Cannot Be Determined A B C D BHI BHS BLS BLO BGT BGE BLE BLT BNE BEQ 7) [6 marks] Determine the final contents of the register used in each code fragment. A) LDAA #% ANDA #% D) LDAB #% EORB #% B) LDAA #% ORAA #% E) LDAB #% COMB 8) [5 marks] For each of the HCS12 instruction below, give the contents of the indicated registers or memory locations. The initial conditions and final conditions are given. If you can t determine the contents from the initial and final conditions, indicate by??. Notes: a) NZVC are the bits in the condition code register. b) The contents of memory location $0100 is represented by [$0100]. c) Label L1 has the value $2000; label L2 has the value $3000. A = $7F B = $01 A = $02 B = Before execution Instruction After execution aba aba A = NZVC = A = NZVC = 0101 A = $81 lsla A = NZC = A = $14 oraa #$08 A = A =[$100] = $FF eora $100 A = $55 [$100] = asr $100 [$100] = $C4 NZVC = 1001 [$100] = $81 bset $100,$0F [$100] = [$100] = $81 brclr $100,$44,L1 Bra L2 PC = C) LDAA #% EORA #% F) LDAA #% ) [6 marks] Find the values of condition flags N, Z, V, and C in the CCR register and the register A after the execution of each of the following instructions, given that [A] = $50 and the condition flags are N = 0, Z = 1, V = 0, and C = 1 ( 3/6)

4 Instruction N Z V C A Initial values $50 Suba #40 TSTA ROLA LSLA 10) [4 marks] Given the following source code: org $6000 ;Line 1 clra ;Line 2 ldx #data ;Line 3 loop ;Line 4 tst 0,x ;Line 5 bmi done ;Line 6 adda 0,x ;Line 7 inx ;Line 8 bra loop ;Line 9 done bra _end ;Line 10 org $7000 ;Line 11 data fcb 3 ;Line 12 fcb 0 ;Line 13 fcb 1 ;Line 14 fcb -1 ;Line 15 fcb 128 ;Line 16 fcb -1 ;Line 17 Assume that the cpu starts executing instructions at address 0x What is the value of index register X following the ldx #data instruction on line 3? 2. How many times will the instruction inx be executed? 3. What will the contents of A be after executing the code? 4. Suppose that Line 15 were changed to fcb 0 (instead of fcb -1) and the code run again from the beginning. What would A contain after executing the code? 11) [4 marks] After the execution of the following instructions, what will be the value of accumulator A? assume for each part (a and b) the A register initially contains $F5 value, and C = 1. (A) tab (B) tab lsld rora lsld rorb lsld lsrd 12) [2 marks] In the following code sequence, assume register Y contains the value $1000 before the code is executed. Which if any of the conditional branches would be satisfied if they were executed for each case? Where does execution actually continue (at what label)? Please explain your answer ( 4/6)

5 Start: cpy #$1234 bcs lab1 blt lab 2 bhs lab3 Next: ) [4 marks] Given the following program: org $7000 stuff fcb 3, 1, 4, 0, -1, 2, 7 org $6000 ldx #stuff ldab #0 loop: ldaa 0,x bmi done addb 0,x inx bra loop done: A) What value (in hex) will be in index register X following the execution of the instruction ldx #stuff? B) What will the values in index register X and accumulators A and B after executing the code? Justify/explain your answer 14) [9 marks] Write a single instruction to perform each of the following:- A) Set bit 7 (the most significant bit) of memory location $900 and leave the other bits unaffected. B) Clear bit 0 (the least significant bit) of memory location $901 and leave the other bits unaffected. C) Toggle both bits 2 and 3 of the B register but leave the other bits unaffected. D) Clear the C, H, and V condition code register bits but leave the others unaffected. E) Set the C and I condition code register bits but leave the others unaffected. F) Branch to NEXT if bit 4 of memory location $1040 is 1. G) Branch to NEXT if bits 3 and 4 of memory location $1016 are 0. H) Branch to NEXT if bits 0, 1, 2, 3, and 4 of memory location $1053 are 1. I) Branch to NEXT if bits 6 and 7 of memory location $1005 are 0. 15) [3 marks] Write one instruction to perform each of the following: A) Divides the unsigned 8-bit binary number in register A by 2. (For example, if A = 8, it would be 4 after division.) B) If A is an even number, convert it to the next bigger odd number. (For example, a 4 would become a 5.) C) Invert the bits 2 and 1 of register A. (For example, in binary would become in binary.) 16) [3 marks] Write assembly code to jump to the location labeled not_a_letter if the letter stored in accumulator A is not a lower or upper case letter. The letter stored in A is in ASCII code. 17) [3 marks] Write an assembly code to put $FF in register A if the character stored in memory location 1000 is an upper case letter, else put $00 in A. ( 5/6)

6 18) [3 marks] Write the instruction that branch to LOOP_L1 address, if bit 0, bit 4, and bit 7 of the memory location at $1500 are all ones (1s). 19) [3 marks] Write an instruction sequence to add the 4 digit BCD number stored at $2000 ~ 2001 and $2002 ~ $2003 and store the sum at $1000 ~ $ ) [3 marks] Write an instruction sequence to divide the unsigned word in register Y by the unsigned word in memory location labeled Word2 and store the quotient in the third word array Clist using indexed addressing. 21) [4 marks] Write HCS12 assembly program to multiply the contents of the memory location at $6000 by the contents of the memory location at $6001 and add the contents of the memory location at $6050 to the product computed above and save the result at $7000 and $ ) [4 marks] Write HCS12 assembly language code to implement the following pseudo code module. Assume that N, NCOUNT, and PCOUNT are 8-bit variables that have been previously defined to be some locations in memory. IF (N < 0) THEN Increment NCOUNT ELSE Increment PCOUNT ENDIF 23) [5 marks] Write HCS12 assembly language code to replace the spaces in a string array with hyphens. The original string is stored at memory locations starting from $800. Assume that the array ends with Null character. Store the modified string starting from the memory location $ ) [4 marks] Write HCS12 assembly language code to swap the upper four bits and the lower four bits of accumulator A (swap bit seven with bit three, bit six with bit two, and so on). 25) [4 marks] Write a program to shift the 6-byte number located at $900-$905 to the right three places. 26) [5 marks] Write a program to compute the average of an array of N 8-bit numbers and store the result at $900. The array is stored at memory locations starting from $800. N is no larger than 255. To reduce the chance of overflow, store the summation in a word. 27) [10 marks] Write a program to create a time delay of approximately 100 seconds by using program loops, assuming that the bus frequency is 24Mhz. What is the approximated delay? How can you make it more accurate? What is the more accurate delay? ( 6/6)