Monday, February 29, 2016

8051 JB Instruction

Jump if Bit set

InstructionJB bit, relative address
FunctionJump if Bit set
Encoding0 0 1 0 0 0 0 0 bit_address A7...A0
OperationPC = PC + 3
IF (bit) = 1
PC = PC + relative address
DescriptionIf the indicated bit is a one, JB jump to the address indicated; otherwise, it proceeds with the next instruction. The branch destination is computed by adding the signed relative-displacement in the third instruction byte to the PC, after incrementing the PC to the first byte of the next instruction. The bit tested is not modified. No flags are affected.
Flags AffectedC AC F0 RS1 RS0 OV P
ExampleThe data present at input port 1 is 11001010B. The Accumulator holds 56 (01010110B). The following instruction sequence,
causes program execution to branch to the instruction at label LABEL2.
Bytes: Number of bytes required to encode the instruction.
Cycles: Number of instruction cycles required to execute the instruction. Note that there are 12 oscillator cycles to one instruction cycle on a standard 8051.
Encoding: Lists the byte encoding for the instruction.
Operation: Lists, step-by-step, the operations performed by the instruction.
Flags Affected: are highlighted in Bold

Related topics:
8051 Boolean Variable Manipulation Instructions   |   8051 CPL Instruction   |   8051 CLR Instruction   |   8051 SETB Instruction   |   8051 ORL Instruction   |   8051 ANL Instruction   |   8051 MOV Instruction   |   8051 JC Instruction   |   8051 JBC Instruction   |   8051 JNC Instruction   |   8051 JNB Instruction

List of topics: 8051

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