STY

STY (short for "STore Y") is the mnemonic for a machine language instruction which stores a copy of the byte held in the Y index register at the RAM or I/O address specified. The contents of the Y index register itself remains unchanged through the operation.

Addressing modes

Opcode		Addressing mode	Assembler format	Length in bytes	Number of cycles
Dec	Hex
140	8C	Absolute	STY nnnn	3	4
132	84	Zeropage	STY nn	2	3
148	94	Zeropage,X	STY nn,X	2	4

STY supports 3 addressing modes, as shown in the table at right. In the assembler formats listed, nn represents a single-byte (8-bit) figure, and nnnn is a two-byte (16-bit) address.

CPU flags

STY does not affect any of the CPU's status flags.