TYA

TYA (short for "Transfer Y to Accumulator") is the mnemonic for a machine language instruction which transfers ("copies") the contents of the Y index register into the accumulator.

Addressing mode

Opcode		Addressing mode	Assembler format	Length in bytes	Number of cycles
Dec	Hex
152	98	Implied	TYA	1	2

TYA only supports the Implied addressing mode, as shown in the table at right.

CPU flags

TYA affects 2 of the CPU's status flags:

• The negative status flag is set if the byte transferred is negative, i.e. has it's most significant bit set.
• The zero flag is set if the byte transferred is zero, or cleared if it is non-zero.