COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
1. Write equivalent C code for the assembly code given below? Update final value of registers in HEX
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_______________________ CX
AX
2. Update Flags after executing following code?
NOTE: AND performs a Boolean(bitwise) AND operation between each pair of matching bits in two
operands and place result in the destination. AND instruction always clear overflow and carry flags. It
modifies Sign, Zero and Parity flags.
Sign
Zero
Carry
Flags
Overflow
Parity
Auxiliary
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
3. Update memory after executing code given below
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
4. Update Flags after executing following code
NOTE: OR performs a Boolean(bitwise) OR operation between each pair of matching bits in two operands and
place result in the destination. OR instruction always clear overflow and carry flags. It modifies Sign, Zero and
Parity flags. Sign
Zero
Carry
Flags
Overflow
Parity
Auxiliary
5. Update memory after executing code given below
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
6. Update register after each line of code and update Flags after executing XOR AL,AH
AX
AX
Sign
AX
Zero AX
Carry AX
Flags
Overflow
Parity AX
Auxiliary Al
AH
AL
7. Write a program that finds parity of number given below? HINT: Use XOR and LOOP to find parity
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
INSTRUCTIONS: (Question 7-11) Perform each of the following operations on word size 2’s
complement numbers and update the answer and value of flags after performing the arithmetic.
Perform all the steps in the “calculation” box, only filling the answer will not get any credit.
8. Update flags after arithmetic instruction? Also state which of the following jumps will taken or not taken
TAKEN NOT TAKEN
Jc
Jz
Jo
Js
jp
Sign Calculation
Zero
Flags Carry
Overflow
Parity
9. Update flags after arithmetic instruction? Also state which of the following jumps will taken or not taken
TAKEN NOT TAKEN
Jc
Jz
Jo
Js
jp
Sign Calculation
Zero
Flags Carry
Overflow
Parity
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
10. Update flags after arithmetic instruction? Also state which of the following jumps will taken or not taken
TAKEN NOT TAKEN
Jnc
Jnz
Jo
Js
jnp
Sign Calculation
Zero
Carry
Flags
Overflow
Parity
Auxiliary
11. Update flags after arithmetic instruction? Also state which of the following jumps will taken or not taken
TAKEN NOT TAKEN
Jc
Jz
Jno
Jns
jp
Sign Calculation
Zero
Carry
Flags
Overflow
Parity
Auxiliary
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
12. Update flags after CMP instruction? Also state which of the following jumps will taken or not taken
RENAME JUMPS: JE= JZ , JNZ= JNE
TAKEN NOT TAKEN
Jz
Je
Jnz
Jne
Sign Calculation
Zero
Carry
Flags
Overflow
Parity
Auxiliary
13. Update value of ax and cx registers after every iteration. Update any changes to the done to flag
1 2 3 4 5 6
CX
AX
Sign Calculation
Zero
Carry
Flags At last iteration Zero and parity flag is set
Overflow
Parity
Auxiliary
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
• For two unsigned operands Zero and Carry Flag indicate the following relationship
• For two signed operands Zero and Carry Flag indicate the following relationship
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
14. Fill flag after every CMP instruction
NOT Sign Calculation
TAKEN TAKEN Zero
Ja
Carry
Jg Flags For unsigned:
Overflow Destination < Source
For Signed:
Parity Destination>Source
Auxiliary
NOT Sign Calculation
TAKEN TAKEN Zero
Jnl Carry For unsigned:
Jnle Flags Destination > Source
Overflow For Signed:
JL Parity Destination < Source
Auxiliary
NOT Sign Calculation
TAKEN TAKEN Zero
JNG Carry
JNGE Flags For unsigned:
Overflow Destination < Source
For Signed:
JGE Parity Destination>Source
Auxiliary
NOT Sign Calculation
TAKEN TAKEN Zero
JG Carry
Flags Destination = Source
JNL Overflow
JLE Parity
Auxiliary
NOT Sign Calculation
TAKEN TAKEN
Zero
JL Flags
Carry Destination = Source
JNG
Overflow
JGE
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
INSTRUCTIONS: (Question 14-15) Dry run the program for each iteration with following
consideration
Example ID 3812
First digit of Your ID1 3
Second digit of Your ID2 8
Third digit of Your ID3 1
Fourth digit of Your ID4 2
15. Dry run program gives below update table for each iteration count total number of iterations took by the
program
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
COUNT SWAP
66 id1 45 id2 40 id3 -25 id4 -10 11
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
16. Dry run program gives below update table for each iteration count total number of iterations took by the
program
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
COUNT SWAP
66 id1 45 id2 40 id3 -25 id4 -10 11
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
17. Modify the program in QUESTION#14 for following data declaration.
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
18. Fill and clear stack using following code
STACK AT END OF
FILL STACK PROGRAM
00C6 00C6
00C8 00C8
00CA 00CA
00CC 00CC
00CE 00CE
00E0 00E0
00E2 00E2
00E4 00E4
00E6 00E6
00E8 00E8
00EA 00EA
00EC 00EC
00FE 00FE
00F0 00F0
00F2 00F2
00F4 00F4
00F6 00F6
00F8 00F8
00FA 00FA
00FC 00FC
00FE 00FE
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
19. Dry run the assembly code given below and update flag register after executing POPF
Sign Calculation
Zero
Flags Carry
Overflow
Parity
20. Update stack after running assembly code given below
STACK AT END OF
FILL STACK PROGRAM
00F0 00F0
00F2 00F2
00F4 00F4
00F6 00F6
00F8 00F8
00FA 00FA
00FC 00FC
00FE 00FE
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
21. Update stack after running assembly code given below
STACK AT END OF
FILL STACK PROGRAM
00F0 00F0
00F2 00F2
00F4 00F4
00F6 00F6
00F8 00F8
00FA 00FA
00FC 00FC
00FE 00FE
22. Update stack after running assembly code given below
STACK AT END OF
FILL STACK PROGRAM
00F0 00F0
00F2 00F2
00F4 00F4
00F6 00F6
00F8 00F8
00FA 00FA
00FC 00FC
00FE 00FE
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
23. Update stack after running assembly code given below
STACK AT END OF
FILL STACK PROGRAM
00C6 00C6
00C8 00C8
00CA 00CA
00CC 00CC
00CE 00CE
00E0 00E0
00E2 00E2
00E4 00E4
00E6 00E6
00E8 00E8
00EA 00EA
00EC 00EC
00FE 00FE
00F0 00F0
00F2 00F2
00F4 00F4
00F6 00F6
00F8 00F8
00FA 00FA
00FC 00FC
00FE 00FE
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
24. Convert the program given in Question#15 to a procedure where it receives array offset and array size
through STACK. It also creates a local variable for swap?
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
INSTRUCTIONS: (Question 23-27) Consider a simple hypothetical machine that includes a single data
register, called an accumulator (AC), 16-bits long instructions and data. Memory is organized using 16-bit
words. The instruction format provides 4 bits for the opcode and 4096 (4K) words of memory can be
directly addressed.
Following Figure is showing the relevant portions of memory:
400 2900 PC 400
401 0901 AC
402 5005 IR
403 4006 MAR
404 6902 MBR
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
PC = Program counter
IR = Instruction register
MAR = Memory address register
MBR = Memory buffer register
I/O AR = Input/output address register
I/O BR = Input/output buffer register
Instruction Format:
16-bit instructions
Bits 0-3 is Operation Code (Op Code)
Bits 4-15 is Address
Operation Codes (Op Code)
0000 Add to AC from memory AC = AC + [Address]
0010 Load AC from memory AC = [Address]
0011 Store AC to memory [Address] = AC
0100 Load AC from I/O AC = [Device_Address]
0101 Load I/O from AC [Device Address] = AC
0110 Subtract memory from AC AC = AC – [Address]
1001 Jump to the address PC = Address
Perform two steps individually for each instruction:
Instruction Fetch
Instruction Execute
After execution of arithmetic operations, set the values of the flags as well after the execution step.
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
25. Instruction Fetch
400 2900 PC 400
401 0901 AC
402 5005 IR 2900
403 4006 MAR 400
404 6902 MBR 2900
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
Instruction Execute
400 2900 PC 401
401 0901 AC 80EF
402 5005 IR 2900
403 4006 MAR 900
404 6902 MBR 80EF
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
26. Instruction Fetch
400 2900 PC 401
401 0901 AC 80EF
402 5005 IR 0901
403 4006 MAR 401
404 6902 MBR 0901
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
Instruction Execute
400 2900 PC 402
401 0901 AC 11EE
402 5005 IR 0901
403 4006 MAR 901
404 6902 MBR 90FF
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
27. Instruction Fetch
400 2900 PC 402
401 0901 AC 11EE
402 5005 IR 5005
403 4006 MAR 402
404 6902 MBR 5005
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 867E
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
Instruction Execute
400 2900 PC 403
401 0901 AC 11EE
402 5005 IR 5005
403 4006 MAR
404 6902 MBR
405 9500 I/OAR 005
406 5006 I/OMR 11EE
407 2902
…... I/O Devices
500 3901 …
…. 005 11EE
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
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COMPUTER ORGANIZATION & ASSEMBLY LANGUAGE
ASSIGNMENT#2 (FALL 2021)
28. Instruction Fetch
400 2900 PC 403
401 0901 AC 11EE
402 5005 IR 4006
403 4006 MAR 403
404 6902 MBR 4006
405 9500 I/OAR
406 5006 I/OMR
407 2902
…... I/O Devices
500 3901 …
…. 005 11EE
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
Instruction Execute
400 2900 PC 404
401 0901 AC 7AEE
402 5005 IR 4006
403 4006 MAR
404 6902 MBR
405 9500 I/OAR 006
406 5006 I/OMR 7AEE
407 2902
…... I/O Devices
500 3901 …
…. 005 11EE
900 80EF 006 7AEE
901 90FF 007 FFFF
902 FFFF ….
Flags Overflow Sign Zero Carry
Values
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