ANC

ANC (short for "Logic ANd altering Carry") is an illegal opcode that works the same as AND, except that the Carry Flag is set to the same state that the Negative Flag is set to.

Addressing modes

Opcode		Addressing mode	Assembler format	Length in bytes	Number of cycles
Dec	Hex
11	0B	Immediate	ANC #nn	2	2
43	2B	Immediate	ANC #nn	2	2

ANC only supports immediate mode, and may have an opcode of either $0B or $2B.

CPU flags

ANC affects 3 of the CPU's status flags:

• The negative flag is set if the result is negative, i.e. has its most significant bit set.
• The zero flag is set if the result is zero, or cleared if it is non-zero.
• The carry flag to the same state that the Negative Flag is set to.

Examples

ANC Opcode

ANC #$00 acts like LDA #$00 followed by CLC

Links

• NMOS 6510 Unintended Opcodes (No More Secrets)