Processor Control Instructions
CLC clear the carry flag to NC (CF←0)
CMC complement (reverse the value of) the carry flag (CF←~CF)
STC set the carry flag to CY (CF←1)
CLD clear direction flag to UP (string ops auto-increment) (DF←0)
STD set direction flag to DN (string ops auto-decrement) (DF←1)
CLI disable maskable hardware interrupts (IF←0)
STI enable maskable hardware interrupts (IF←1)
CTS/CLTS clear task switch flag. (TF←1) 286+
HLT halt processing (perform NOPs until an interrupt occurs)
WAIT/FWAIT wait for TEST line active (synchronize with coprocessor)
LOCK (prefix) prevent coprocessor bus access for the next instruction
prevents access only to mem affected by next opcode 386+
SEG segreg (prefix) override default segreg for next EA calculation
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Instruction Set