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JB Jump If Below Flags: not altered
JB short-label
Jump Condition: Jump if CF = 1
Used after a CMP or SUB instruction, JB transfers control to short-
label if the first operand was less than the second. (Both operands
are treated as unsigned numbers.) The target of the jump must be
within -128 to +127 bytes of the next instruction.
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Operands Clocks Transfers Bytes Example
short-label 16 or 4 - 2 JB BELOW
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Notes: JC (Jump if Carry), JB, and JNAE (Jump if Not Above
or Equal), are all synonyms for the same
instruction.
JB, Jump if Below, should be used when comparing
unsigned numbers.
JL, Jump if Less Than, should be used when comparing
signed numbers.