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Answers for Lab 07 (MARIE assembly language)
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- Ian! D. Allen - idallen@idallen.ca - www.idallen.com

Not all questions will be marked - check all your answers against this
answer sheet.

References: ECOA2e Section 4.1-4.6, 4.8.1-4.9.1, 4.9.3, 4.10, 4.11.1,
    5.4.2 and associated Chapter Slides
    Class Notes (via course home page): text_errata.txt

Class Notes under http://teaching.idallen.com/cst8214/07f/
    text_errata.txt

1.
 1.1. fetch from memory (at location in PC), the instruction into the IR
 1.2. increment PC by length of instruction
 1.3. decode and execute the instruction from its place in the IR

2. to the instruction that follows the current instruction

3. False (Skipcond uses it differently; Halt doesn't use it at all)

4. the "English" name of the instruction, e.g. Jump, AddI

5. machine code

6. assembly language

7. True

8. an assembler

9. 0x8000

10. MAR<--X, MBR<--M[MAR], AC<--AC+MBR

11. PC<--X 

12.  1AB9, 3ABA, 2ABB, 7000, 0023, FFE9, 0000

13. object code; an object file

14. True

15. True

16.
            AC   IR MAR  MBR  PC
load x    0020 1004 004 0020 001
add y     0011 3005 005 FFF1 002
store z   0011 2006 006 0011 003
halt      0011 7000 003 XXXX 004     XXXX = 0011 or 7000

17. 1CF6, 3CF7, 2CF8, 7000, 0020, FFF1, 0000

18.  1A27 3A28 9A25 3A28 2A27 7000 3A27 9A22 0023 0001

19.
   S2    A22
   S1    A25
   A     A27
   One   A28

20. PC,MAR only need 12 bits to hold a 12-bit MARIE memory address
    AC,MBR need to hold a full 16-bit memory content value (data)

21. i) Store 007  ii) Jump 00B   iii) Add 009

22.
    Immediate  2000
    Direct     2200
    Indirect   2600
    Indexed (with R1)  3600

23.
    MAR <-- X
    MBR <-- M[MAR]
    MAR <-- MBR
    MBR <-- M[MAR]
    AC  <-- MBR

24.
    Immediate  1000
    Direct     1400
    Indirect   1300
    Indexed (with R1)  1000

25.
    Immediate  500
    Direct     100
    Indirect   600
    Indexed (with R1)  800