Branch Instruction Of 8051 controller

Branch Instructions

There are two kinds of branch instructions:

Unconditional jump instructions: upon their execution a jump to a new location from where the program continues execution is executed.

Conditional jump instructions: a jump to a new program location is executed only if a specified condition is met. Otherwise, the program normally proceeds with the next instruction.

ACALL addr11 - Absolute subroutine call

addr11: Subroutine address

Description: Instruction unconditionally calls a subroutine located at the specified code address. Therefore, the current address and the address of called subroutine must be within the same 2K byte block of the program memory, starting from the first byte of the instruction following ACALL.

EXAMPLE:

Before execution: PC=0123h
After execution: PC=0345h

AJMP addr11 - Absoulte jump

addr11: Jump address

Description: Program continues execution after executing a jump to the specified address. Similar to the ACALL instruction, the jump must be executed within the same 2K byte block of program memory starting from the first byte of the instruction following AJMP.

EXAMPLE:

Before execution: PC=0345h SP=07h
After execution: PC=0123h SP=09h

CJNE A,direct,rel - Compares direct byte to the accumulator and jumps if not equal

A: accumulator
 Direct: arbitrary register with address 0-255 (0-FFh)
 addr: jump address

Description: Instruction first compares the number in the accumulator with the directly addressed byte. If they are equal, the program proceeds with execution. Otherwise, a jump to the specified address will be executed. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to +127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0145h A=27h
After execution: if MAX≠27: PC=0123h
If MAX=27: PC=0146h

CJNE A,#data,rel - Compares immediate data to the accumulator and jumps if not equal

A: accumulator
 Data: constant in the range of 0-255 (0-FFh)

Description: Instruction first compares the number in the accumulator with the immediate data. If they are equal, the program proceeds with execution. Otherwise, a jump to the specified address will be executed. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to +127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0445h
After execution: If A≠33: PC=0423h
If A=33: PC=0446h

CJNE Rn,#data,rel - Compares immediate data to the register Rn and jumps if not equal

Rn: Any R register (R0-R7)
 Data: Constant in the range of 0 - 255 (0-FFh)
 addr: Jump address

Description: Instruction first compares immediate data to the register Rn. If they are equal, the program proceeds with execution. Otherwise, a jump to the specified address will be executed. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0345h
After execution: If R5≠44h: PC=0323h
If R5=44h: PC=0346h

CJNE @Ri,#data,rel - Compares immediate data to indirectly addressed register and jumps if not equal

Ri: Register R0 or R1
 Data: Constant in the range of 0 - 255 (0-FFh)

Description: This instruction first compares immediate data to indirectly addressed register. If they are equal, the program proceeds with execution. Otherwise, a jump to the specified address in the program will be executed. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to +127 locations relative to the next instruction).

EXAMPLE:

Before execution: Register Address SUM=F3h
PC=0345h R0=F3h
After execution: If SUM≠44h: PC=0323h
If SUM=44h: PC=0346h

DJNZ direct,rel - Decrements direct byte by 1 and jumps if not 0

Direct: arbitrary register with address 0-255 (0-FFh)
 addr: Jump address

Description: This instruction first decrements value in the register. If the result is 0, the program proceeds with execution. Otherwise, a jump to the specified address in the program will be executed. As it is direct addressing, the register must be within the first 255 locations of RAM. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to +127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0445h
After execution: If CNT≠0: PC=0423h
If CNT=0: PC=0446h

DJNZ Rn,rel - Decrements the Rn register by 1 and jumps if not 0

Rn: any R register (R0-R7)
 addr: jump address

Description: This instruction first decrements the value in the Rn register. If the result is 0, the program proceeds with execution. Otherwise, a jump to the specified address in the program will be executed. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (- 128 to +127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0445h
After execution: If R1≠0: PC=0423h
If R1=0: PC=0446h

JB bit,rel - Jump if direct bit is set

addr: Jump address
 Bit: any bit of RAM

Description: If the bit is set, a jump to the specified address will be executed. Otherwise, if the value of bit is 0, the program proceeds with the next instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-128 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If P0.5=0: PC=0324h
If P0.5=1: PC=0345h

JC rel - Jump if carry flag is set

addr: Jump address

Description: Instruction first checks if the carry flag is set. If set, a jump to the specified address is executed. Otherwise, the program proceeds with the next instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before instruction: PC=0323h
After instruction: If C=0: PC=0324h
If C=1: PC=0345h

JBC bit,rel - Jump if direct bit is set

Bit: any bit of RAM
 addr: Jump Address

Description: This instruction first checks if the bit is set. If set, a jump to the specified address is executed and the bit is cleared. Otherwise, the program proceeds with the first following instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If TEST0.4=1: PC=0345h, TEST0.4=0
If TEST0.4=0: PC=0324h, TEST0,4=0

JNB bit,rel - Jump if direct bit is not set

addr: Jump address
 Bit: any bit of RAM

Description: If the bit is cleared, a jump to the specified address will be executed. Otherwise, if the bit value is 1, the program proceeds with the first following instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If P0.5=1: PC=0324h
If P0.5=0: PC=0345h

JMP @A+DPTR - Jump indirect relative to the DPTR

A: accumulator
 DPTR: Data Pointer

Description: This instruction causes a jump to the address calculated by adding value stored in the accumulator to the 16-bit number in the DPTR Register. It is used with complex program branching where the accumulator affects jump address, for example when reading a table. Neither accumulator nor DPTR register are affected.

EXAMPLE:

Before execution: PC=223 DPTR=1400h
After execution: PC = 1402h if A=2
PC = 1404h if A=4
PC = 1406h if A=6

Note:
As instructions AJMP LABELS occupy two locations each, the values in the accumulator specifying them must be different from each other by 2.

JNZ rel - Jump if accumulator is not zero

addr: Jump Address

Description: This instruction checks if the value stored in the accumulator is 0. If not, a jump to the specified address will be executed. Otherwise, the program proceeds with the first following instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If A=0: PC=324h
If A≠0: PC=283h

JNC rel - Jump if carry flag is not set

addr: Jump Address

Description: This instruction first checks whether the carry flag is set. If not, a jump to the specified address will be executed. Otherwise, the program proceeds with the first following instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If C=0: PC=360h
If C=1: PC=324h

LCALL addr16 - Long subroutine call

addr16: Subroutine Address

Description: This instruction unconditionally calls a subroutine located at the specified address. The current address and the start of the subroutine called can be located anywhere within the memory space of 64K.

EXAMPLE:

Before execution: PC=0123h
After execution: PC=1234h

JZ rel - Jump if accumulator is zero

addr: Jump Address

Description: The instruction checks whether the value stored in the accumulator is 0. If yes, a jump to the specified address will be executed. Otherwise, the program proceeds with the following instruction. This is a short jump instruction, which means that the address of a new location must be relatively near the current one (-129 to + 127 locations relative to the first following instruction).

EXAMPLE:

Before execution: PC=0323h
After execution: If A0: PC=324h
If A=0: PC=283h

LJMP addr16 - Long jump

addr16: jump address

Description: Instruction causes a jump to the specified 16-bit address.

EXAMPLE:

Before execution: PC=0123h
After execution: PC=1234h

RET - Return from subroutine

Description: This instruction ends every subroutine. After execution, the program proceeds with the instruction following an ACALL or LCALL.

EXAMPLE:

RETI - Return from interrupt

Description: This instruction ends every interrupt routine and informs processor about it. After executing the instruction, the program proceeds from where it left off. The PSW is not automatically returned its pre-interrupt status.

SJMP rel - Short Jump (relative address)

addr: Jump Address

Description: Instruction enables jump to the new address which should be in the range of -128 to +127 locations relative to the first following instruction.

EXAMPLE:

Before execution: PC=323
After execution: PC=345

Next Post:       Data Transfer Instruction
Previous Post:Arithmetic Instruction
 
Related Topics:

-> Function of microcontroller 8051 ports
-> what is RS-232
-> How to install Android Apps

-> Program Status Word-(PSW) of 8051
-> Internal RAM structure of 8051 comtroller 

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Data Transfer Instruction of 8051 controller

Data Transfer Instruction of 8051

This instructions are used to copy the content of source operand to Destination operand

MOV A,Rn - Moves the Rn register to the accumulator

The instruction moves the Rn register to the accumulator. The Rn register is not affected.

EXAMPLE:

 

Before execution: R3=58h
After execution: R3=58h A=58h

MOV A,@Ri - Moves the indirect RAM to the accumulator

Description: Instruction moves the indirectly addressed register of RAM to the accumulator. The register address is stored in the Ri register (R0 or R1). The result is stored in the accumulator. The register is not affected.

EXAMPLE:

Register Address SUM=F2h R0=F2h
Before execution: SUM=58h
After execution: A=58h SUM=58h

MOV A,direct - Moves the direct byte to the accumulator

Description: Instruction moves the direct byte to the accumulator. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh. (0-127 dec.). After executing the instruction, the register is not affected.

EXAMPLE:

Before execution: Rx=68h
After execution: Rx=68h A=68h

MOV Rn,A - Moves the accumulator to the Rn register

Desription: Instruction moves the accumulator to the Rn register. The accumulator is not affected.

EXAMPLE:

Before execution: A=58h
After execution: R3=58h A=58h

MOV A,#data - Moves the immediate data to the accumulator

Desription: Instruction moves the immediate data to the accumulator.

EXAMPLE:

After execution: A=28h

MOV Rn,#data - Moves the immediate data to the Rn register

Description: Instruction moves the immediate data to the Rn register.

After execution: R5=32h

MOV Rn,direct - Moves the direct byte to the Rn register

Description: Instruction moves the direct byte to the Rn register. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh. (0-127 dec.). After executing the instruction, the register is not affected.

EXAMPLE:

Before execution: SUM=58h
After execution: SUM=58h R3=58h

MOV direct,Rn - Moves the Rn register to the direct byte

Description: Instruction moves the Rn register to the direct byte. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh. (0-127 dec.). After executing the instruction, the register is not affected.

EXAMPLE:

Before execution: R3=18h
After execution: R3=18h CIF=18h

MOV direct,A - Moves the accumulator to the direct byte

Description: Instruction moves the accumulator to the direct byte. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh. (0-127 dec.). After executing the instruction, the register is not affected.

EXAMPLE:

Before execution: A=98h
After execution: A=98h REG=98h

MOV direct,@Ri - Moves the indirect RAM to the direct byte

Description: Instruction moves the indirectly adressed register of RAM to the direct byte. The register is not affected.

EXAMPLE:

Register Address SUM=F3
Before execution: SUM=58h R1=F3
After execution: SUM=58h TEMP=58h

MOV direct1,direct2 - Moves the direct byte to the direct byte

Description: Instruction moves the direct byte to another direct byte. As it is direct addressing, both registers can be any SFRs or general-purpose registers with address 0-7Fh. (0-127 dec.). The direct1 is not affected.

EXAMPLE:

Before execution: TEMP=58h
After execution: TEMP=58h SUM=58h

MOV @Ri,A - Moves the accumulator to the indirect RAM

Description: Instruction moves the accumulator to the indirectly addressed register of RAM. The register address is stored in the Ri register (R0 or R1). After executing the instruction, the accumulator is not affected.

EXAMPLE:

Register Address SUM=F2h
Before execution: R0=F2h A=58h
After execution: SUM=58h A=58h

MOV direct,#data - Moves the immediate data to the direct byte

Description: Instruction moves the immediate data to the direct byte. As it is direct addressing, the direct byte can be any SFRs or general-purpose register with address 0-7Fh. (0-127 dec.).

EXAMPLE:

After execution: TEMP=22h

MOV @Ri,#data - Moves the immediate data to the indirect RAM

Description: Instruction moves the immediate data to the idirectly addressed register of RAM. The register address is stored in the Ri register (R0 or R1).

EXAMPLE:

Register address TEMP=E2h
Before execution: R1=E2h
After execution: TEMP=44h

MOV @Ri,direct - Moves the direct byte to the indirect RAM

Description: Instruction moves the direct byte to a register the address of which is stored in the Ri register (R0 or R1). After executing the instruction, the direct byte is not affected.

EXAMPLE:

Register address TEMP=E2h
Before execution: SUM=58h R1=E2h
After execution: SUM=58h TEMP=58h

MOVC A,@A+DPTR - Moves the code byte relative to the DPTR to the accumulator

Description: Instruction first adds the 16-bit DPTR register to the accumulator. The result of addition is then used as a memory address from which the 8-bit data is moved to the accumulator.

EXAMPLE:

Before execution:
DPTR=1000:
A=0
A=1
A=2
A=3

After execution:
A=66h
A=77h
A=88h
A=99h

Note: DB (Define Byte) is a directive in assembly language used to define constant.

MOV DPTR,#data16 - Loads the data pointer with a 16-bit constant

Description: Instruction stores a 16-bit constant to the DPTR register. The 8 high bits of the constant are stored in the DPH register, while the 8 low bits are stored in the DPL register.

EXAMPLE:

After execution: DPH=12h DPL=34h

MOVX A,@Ri - Moves the external RAM (8-bit address) to the accumulator

Description: Instruction reads the content of a register in external RAM and moves it to the accumulator. The register address is stored in the Ri register (R0 or R1).

EXAMPLE:

Register Address: SUM=12h
Before execution: SUM=58h R0=12h
After execution: A=58h

Note:
SUM Register is stored in external RAM which is 256 bytes in size.

MOVC A,@A+PC - Moves the code byte relative to the PC to the accumulator

Description: Instruction first adds the 16-bit PC register to the accumulator (the current program address is stored in the PC register). The result of addition is then used as a memory address from which the 8-bit data is moved to the accumulator.

EXAMPLE:

After the subroutine "Table" has been executed, one of four values is stored in the accumulator:

Before execution:
A=0
A=1
A=2
A=3

After execution:
A=66h
A=77h
A=88h
A=99h

Note: DB (Define Byte) is a directive in assembly language used to define constant.

MOVX @Ri,A - Moves the accumulator to the external RAM (8-bit address)

Description: Instruction moves the accumulator to a register stored in external RAM. Its address is stored in the Ri register.

EXAMPLE:

 

Register address: SUM=34h

Before execution: A=58 R1=34h
After execution: SUM=58h

NOTE:
Register SUM is located in external RAM which is 256 bytes in size.

MOVX A,@DPTR - Moves the external memory (16-bit address) to the accumulator

Description: Instruction moves the content of a register in external memory to the accumulator. The 16-bit address of the register is stored in the DPTR register (DPH and DPL).

EXAMPLE:

Register address: SUM=1234h
Before execution: DPTR=1234h SUM=58
After execution: A=58h

Note:
Register SUM is located in external RAM which is up to 64K in size.

MOVX @DPTR,A - Moves the accumulator to the external RAM (16-bit address)

Description: Instruction moves the accumulator to a register stored in external RAM. The 16-bit address of the register is stored in the DPTR register (DPH and DPL).

EXAMPLE:

Register address: SUM=1234h
Before execution: A=58 DPTR=1234h
After execution: SUM=58h

Note:
Register SUM is located in RAM which is up to 64K in size.


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Related Topics:

-> Function of microcontroller 8051 ports
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-> Reset & Oscillator Circuit of 8051 Micro-Controller
-> Program Status Word-(PSW) of 8051
-> Internal RAM structure of 8051 comtroller

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Logical instruction of 8051

Logical Instruction Of 8051 Micro-Controller

Logic instructions perform logic operations upon corresponding bits of two registers. After execution, the result is stored in the first operand.

ANL A,Rn - AND register to the accumulator
A: accumulator
 Rn: any R register (R0-R7)
Description: Instruction performs logic AND operation between the accumulator and Rn register. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
R5= 55h (01010101 Bin.)
After execution: A= 41h (01000001 Bin.)

ANL A,direct - AND direct byte to the accumulator
A: accumulator
 Direct: arbitrary register with address 0 - 255 (0 - FFh)
Description: Instruction performs logic AND operation between the accumulator and drect register. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (o-127 dec.). The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
MASK= 55h (01010101 Bin.)
After execution: A= 41h (01000001 Bin.)

ANL A,@Ri - AND indirect RAM to the accumulator
A: accumulator
 Ri: Register R0 or R1
Description: Instruction performs logic AND operation between the accumulator and register. As it is indirect addressing, the register address is stored in the Ri register (R0 or R1). The result is stored in the accumulator.

EXAMPLE:

Register address SUM = 4Fh R0=4Fh
Before execution: A= C3h (11000011 Bin.)
R0= 55h (01010101 Bin.)
After execution: A= 41h (01000001 Bin.)

ANL A,#data - AND immediate data to the accumulator
A: accumulator
 Data: constant in the range of 0-255 (0-FFh)
Description: Instruction performs logic AND operation between the accumulator and data. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
After execution: A= 41h (01000001 Bin.)

ANL direct,A - AND accumulator to direct byte
Direct: arbitrary register with address 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs logic AND operation between direct byte and accumulator. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the direct byte.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
MASK= 55h (01010101 Bin.)
After execution: MASK= 41h (01000001 Bin.)

ANL direct,#data - AND immediate data to direct byte
Direct: Arbitrary register with address 0 - 255 (0 - FFh)
 Data: constant in the range between 0-255 (0-FFh)
Description: Instruction performs logic AND operation between direct byte and data. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the direct byte.

EXAMPLE:

Before execution: X= C3h (11000011 Bin.) MASK= 55h (01010101 Bin.) After execution: MASK= 41h (01000001 Bin.)

ANL C,bit - AND direct bit to the carry flag
C: Carry flag
EXAMPLE:


Before execution: ACC= 43h (01000011 Bin.)
C=1
After execution: ACC= 43h (01000011 Bin.)
C=0


ANL C,/bit - AND complements of direct bit to the carry flag
C: carry flag
 Bit: any bit of RAM
Description: Instruction performs logic AND operation between inverted addressed bit and the carry flag. The result is stored in the carry flag.

EXAMPLE:

Before execution: ACC= 43h (01000011 Bin.)
C=1
After execution: ACC= 43h (01000011 Bin.)
C=1

ORL A,Rn - OR register to the accumulator
Rn: any R register (R0-R7)
 A: accumulator
Description: Instruction performs logic OR operation between the accumulator and Rn register. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
R5= 55h (01010101 Bin.)
After execution: A= D7h (11010111 Bin.)

ORL A,@Ri - OR indirect RAM to the accumulator
Ri: register R0 or R1
 A: accumulator
Description: Instruction performs logic OR operation between the accumulator and a register. As it is indirect addressing, the register address is stored in the Ri register (R0 or R1). The result is stored in the accumulator.
d;
EXAMPLE:

Register address: TEMP=FAh
Before execution: R1=FAh
TEMP= C2h (11000010 Bin.)
A= 54h (01010100 Bin.)
After execution: A= D6h (11010110 Bin.)

ORL A,direct - OR direct byte to the accumulator
Direct: arbitrary register with address 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs logic OR operation between the accumulator and a register. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
LOG= 54h (01010100 Bin.)
After execution: A= D6h (11010110 Bin.)

ORL direct,A - OR accumulator to the direct byte
Direct: arbitrary register with address 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs logic OR operation between a register and accumulator. As it is direct addressing, the register can be any SFRs or general- purpose register with address 0-7Fh (0-127 dec.). The result is stored in the register.

EXAMPLE:

Before execution: TEMP= C2h (11000010 Bin.)
A= 54h (01010100 Bin.)
After execution: A= D6h (11010110 Bin.)

ORL A,#data - OR immediate data to the accumulator
Data: constant in the range of 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs logic OR operation between the accumulator and the immediate data. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
After execution: A= C3h (11000011 Bin.)

ORL C,bit - OR direct bit to the carry flag
C: Carry flag
 Bit: any bit of RAM
Description: Instruction performs logic OR operation between the direct bit and the carry flag. The result is stored in the carry flag.

EXAMPLE:

Before execution: ACC= C6h (11001010 Bin.)
C=0
After execution: C=1

ORL direct,#data - OR immediate data to direct byte
Direct: arbitrary register with address 0-255 (0-FFh)
 Data: constant in the range of 0-255 (0-FFh)
Description: Instruction performs logic OR operation between the immediate data and the direct byte. As it is direct addressing, the direct byte can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the direct byte.

EXAMPLE:

Before execution: TEMP= C2h (11000010 Bin.)
After execution: A= D2h (11010010 Bin.)


XRL A,Rn - Exclusive OR register to accumulator
Rn: any R register (R0-R7)
 A: accumulator
Description: Instruction performs exclusive OR operation between the accumulator and the Rn register. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C3h (11000011 Bin.)
R3= 55h (01010101 Bin.)
After execution: A= 96h (10010110 Bin.)

Register address: SUM=E3
Before execution: R0=E3 SUM=29h A=A8h,
After execution: A=A9h, SUM=28h

XRL A,@Ri - Exclusive OR indirect RAM to the accumulator
Ri: Register R0 or R1
 A: accumulator
Description: Instruction performs exclusive OR operation between the accumulator and the indirectly addressed register. As it is indirect addressing, the register address is stored in the Ri register (R0 or R1). The result is stored in the accumulator.

EXAMPLE:

Register address: TEMP=FAh, R1=FAh
Before execution: TEMP= C2h (11000010 Bin.)
A= 54h (01010100 Bin.)
After execution: A= 96h (10010110 Bin.)

XRL A,direct - Exclusive OR direct byte to the accumulator
Direct: Arbitrary register with address 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs exclusive OR operation between the accumulator and the direct byte. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
LOG= 54h (01010100 Bin.)
After execution: A= 96h (10010110 Bin.)

XRL direct,A - Exclusive OR accumulator to the direct byte
Direct: arbitrary register with address 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs exclusive OR operation between the direct byte and the accumulator. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the register.

EXAMPLE:

Before execution: TEMP= C2h (11000010 Bin.)
A= 54h (01010100 Bin.)
After execution: A= 96h (10010110 Bin.)

XRL A,#data - Exclusive OR immediate data to the accumulator
Data: constant in the range of 0-255 (0-FFh)
 A: accumulator
Description: Instruction performs exclusive OR operation between the accumulator and the immediate data. The result is stored in the accumulator.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
X= 11h (00010001 Bin.)
After execution: A= D3h (11010011 Bin.)

XRL direct,#data - Exclusive OR immediate data to direct byte
Direct: arbitrary register with address 0-255 (0-FFh)
 Data: constant in the range of 0-255 (0-FFh)
Description: Instruction performs exclusive OR operation between the immediate data and the direct byte. As it is direct addressing, the register can be any SFRs or general-purpose register with address 0-7Fh (0-127 dec.). The result is stored in the register.

EXAMPLE:

Before execution: TEMP= C2h (11000010 Bin.)
X=12h (00010010 Bin.)
After execution: A= D0h (11010000 Bin.)

CLR A - Clears the accumulator
A: accumulator
Description: Instruction clears the accumulator.

EXAMPLE:

After execution: A=0

CPL A - Complements the accumulator
A: accumulator
Description: Instruction complements all the bits in the accumulator (1==>0, 0==>1).

EXAMPLE:

Before execution: A= (00110110)
After execution: A= (11001001)

RL A - Rotates the accumulator one bit left
A: accumulator
Description: Eight bits in the accumulator are rotated one bit left, so that the bit 7 is rotated into the bit 0 position.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
After execution: A=85h (10000101 Bin.)


RR A - Rotates the accumulator one bit right
A: accumulator
Description: All eight bits in the accumulator are rotated one bit right so that the bit 0 is rotated into the bit 7 position.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
After execution: A= 61h (01100001 Bin.)

RLC A - Rotates the accumulator one bit left through the carry flag
A: accumulator
Description: All eight bits in the accumulator and carry flag are rotated one bit left. After this operation, the bit 7 is rotated into the carry flag position and the carry flag is rotated into the bit 0 position.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
C=0
After execution: A= 85h (10000100 Bin.)
C=1


RRC A - Rotates the accumulator one bit right through the carry flag
A: accumulator
Description: All eight bits in the accumulator and carry flag are rotated one bit right. After this operation, the carry flag is rotated into the bit 7 position and the bit 0 is rotated into the carry flag position.

EXAMPLE:

Before execution: A= C2h (11000010 Bin.)
C=0
After execution: A= 61h (01100001 Bin.)
C=0

 SWAP A - Swaps nibbles within the accumulator
A: accumulator
Description: A nibble refers to a group of 4 bits within one register (bit0-bit3 and bit4-bit7). This instruction interchanges high and low nibbles of the accumulator.

EXAMPLE:


Before execution: A=E1h (11100001)bin.
After execution: A=1Eh (00011110)bin.

Next Post: Arithmetic Instruction
 
Related Topics:

-> Instruction set of 8051 microcontroller
-> I/O PROGRAMMING OF 8051
-> Reset & Oscillator Circuit of 8051 Micro-Controller
-> Program Status Word-(PSW) of 8051
-> Internal RAM structure of 8051 comtroller

Read More