STC:
- It sets the carry flag to 1.
CLC:
- It clears the carry flag to 0.
CMC:
- It complements the carry flag.
STD:
- It sets the direction flag to 1.
- If it is set, string bytes are accessed from higher memory address to lower memory address.
CLD:
- It clears the direction flag to 0.
- If it is reset, the string bytes are accessed from lower memory address to higher memory address.
