LDX

LDX (short for "LoaD X") 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 X 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
162	A2	Immediate	LDX #nn	2	2
174	AE	Absolute	LDX nnnn	3	4
190	BE	Absolute,Y	LDX nnnn,Y	3	4*
166	A6	Zeropage	LDX nn	2	3
182	B6	Zeropage,Y	LDX nn,Y	2	4

LDX 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 LDX 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

LDX affects 2 of the CPU's status flags:

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