STY
From C64-Wiki
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.
[edit] 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.
[edit] CPU flags
STY does not affect any of the CPU's status flags.
