LDY

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 content of the memory location is not affected by the operation.

Addressing modes

Opcode		Addressing mode	Assembler format	Length in bytes	Number of cycles
Dec	Hex
160	A0	Immediate	LDY #nn	2	2
172	AC	Absolute	LDY nnnn	3	4
188	BC	Absolute,X	LDY nnnn,X	3	4*
164	A4	Zeropage	LDY nn	2	3
180	B4	Zeropage,X	LDY nn,X	2	4

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.

CPU flags

LDY affects 2 of the CPU's status flags:

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