| Opcode | Instruction | Op/En | 64-Bit Mode | Compat/Leg Mode | Description |
|---|---|---|---|---|---|
| F9 | STC | NP | Valid | Valid | Set CF flag. |
| Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
| NP | NA | NA | NA | NA |
Sets the CF flag in the EFLAGS register. Operation is the same in all modes.
CF ← 1;
The CF flag is set. The OF, ZF, SF, AF, and PF flags are unaffected.
#UD
If the LOCK prefix is used.