List the current contents of the following registers before program execution. C
ID: 3734864 • Letter: L
Question
List the current contents of the following registers before program execution.
CS = A034
IP =0100
AX =FFFF
BX =E0F0
CX =0023
DX =2020
SP =FFFE
BP =F100
SI =0010
DI =0020
DS =0800
ES =D200
SS =E100
What registers/memory location(s) do you expect to be changed upon the execution of the following instruction.
The above is an example of ___________________________ Addressing
Where is the effective address of the above instruction ______________________________
What are the expected results of above instruction
CS =
IP =
AX =
BX =
CX =
DX =
SP =
BP =
SI =
DI =
DS =
ES =
SS =
Memory Address and contents of location (if applicable) ______________________________________
CS = A034
IP =0100
AX =FFFF
BX =E0F0
CX =0023
DX =2020
SP =FFFE
BP =F100
SI =0010
DI =0020
DS =0800
ES =D200
SS =E100
Explanation / Answer
Immediate Addressing mode allows a constant (e.g. F020) to be specified as source. As such, the above is an example of Immediate Addressing.
Instruction: MOV AX, F020
Effective address (of above instruction)
= Base Address + Offset
= CS hex digits shifted left by one + IP
= A0340 + 0100
= A0440
Given size of above MOV instruction (hex b820f0) = 3 bytes
Expected results of above instruction.
CS = A034
IP = 0104 (incremented by size of MOV instruction after considering word alignment)
AX = F020 (due to MOV instruction)
BX = E0F0
CX = 0023
DX = 2020
SP = FFFE
BP = F100
SI = 0010
DI = 0020
DS = 0800
ES = D200
SS = E100
Memory Address and contents of location (if applicable): Not Applicable
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