Correct Answer - Option 4 : Immediate Addressing
Concept:
The different modes are listed below with the syntax.
|
Addressing Mode
|
Function
|
Syntax
|
Remarks
|
|
Direct
|
The source and destination can be either a register or a RAM location but both can’t be the same.
|
MOV A, R0
|
Direct addressing places the value 55H in the accumulator.
|
|
Indirect
|
Accesses the data at the address placed inside a register. We use the (@) symbol for this purpose.
|
MOV R0, #55H
MOV A, @ R0
|
Indirect addressing places the value 55H in R0
Places the data stored in the memory location 55H in the accumulator.
|
|
Register
|
The source and destination both are registers.
|
MOV A, R0
|
Move the contents from R0 to the register.
|
|
Immediate
|
Data is directly put into registers.
|
MOV A, # 50H
|
Move the data directly to the accumulator.
|
Explanation:
The XCH operation and the possible modes are listed below the table.
|
Instructions
|
Opcode
|
Bytes
|
Cycles
|
Flags
|
|
XCH A, @R0
|
0xC6
|
1
|
1
|
None
|
|
XCH A, @ R1
|
0xC7
|
1
|
1
|
None
|
|
XCH A, R0
|
0xC8
|
1
|
1
|
None
|
|
XCH A, R1
|
0xC9
|
1
|
1
|
None
|
|
XCH A, R2
|
0xCA
|
1
|
1
|
None
|
|
XCH A, R3
|
0xCB
|
1
|
1
|
None
|
|
XCH A, R4
|
0xCC
|
1
|
1
|
None
|
|
XCH A, R5
|
0xCD
|
1
|
1
|
None
|
|
XCH A, R6
|
0xCE
|
1
|
1
|
None
|
|
XCH A, R7
|
0xCF
|
1
|
1
|
None
|
|
XCH A, iram addr
|
0xC5
|
2
|
1
|
None
|
Conclusion:
Immediate addressing mode is not usable in XCH instruction of 8051 microcontroller
