LDY (short for "LoaD Y") is the mnemonic for a machine language instruction which retrieves a copy from the specified RAM or I/O address, and stores it in the Y index register. The contents of the memory address is not affected by the opration.
LDY supports the five addressing modes 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.
With some addressing forms (marked with an asterisk, *, in the "Number of cycles" column) the execution time for LDY depends on the circumstances: In cases where the indexing requires the CPU to "reach across" a page boundary from the base address, the execution time is 1 cycle longer than listed here.
LDY affects 2 of the CPU's status flags: