LDY (Load Y Index With Memory) loads the Y Index Register with the specified memory. It is similar in function to LDA and LDX opcodes. Unlike LDA, there aren't as many addressing modes available for LDY.
Operation
This pseudo C code shows how the LDY opcode functions when it is executed.
SET_NEGATIVE(Operand); // Clears the Negative Flag if the Operand is $#00-7F, otherwise sets it.
SET_ZERO(Operand); // Sets the Zero Flag if the Operand is $#00, otherwise clears it.
Y_INDEX = Operand; // Stores the Operand in the Y Index Register.
Addressing Modes
| Addressing Mode
|
Assembly Language Form
|
Opcode
|
# Bytes
|
# Cycles
|
| Immediate
|
LDY #Operand
|
A0
|
2
|
2
|
| Zero Page
|
LDY Operand
|
A4
|
2
|
3
|
| Zero Page, X
|
LDY Operand, X
|
B4
|
2
|
4
|
| Absolute
|
LDY Operand
|
AC
|
3
|
4
|
| Absolute, X
|
LDY Operand, X
|
BC
|
3
|
4*
|
| * Add 1 if page boundary is crossed.
|
Examples
