LDY
Load Index Register Y from Memory
Load index register Y with data from memory.
On all processors, the data loaded from memory is 8-bit. However, for 16-bit processors with the m flag is clear then the data added is 16-bit with the low-order 8-bits at the effective address and the high-order 8-bits at the effective address plus one.
Flags Affected
| Flags |
| ||||||||
|---|---|---|---|---|---|---|---|---|---|
| n | Set if most-significant bit of result is set | ||||||||
| z | Set if result is zero |
Instructions
| Syntax | Opcode | Available on: | # of | # of | Addressing Mode | ||
|---|---|---|---|---|---|---|---|
| (hex) | 6502 | 65C02 | 65816 | bytes | cycles | ||
| LDY #const | A0 | x | x | x | 21 | 22 | Immediate |
| LDY addr | AC | x | x | x | 3 | 42 | Absolute |
| LDY dp | A4 | x | x | x | 2 | 32, 3 | Direct Page |
| LDY addr,X | BC | x | x | x | 3 | 42, 4 | Absolute Indexed X |
| LDY dp,X | B4 | x | x | x | 2 | 42, 3 | Direct Page Indexed X |
Notes:
- 65816: Add 1 byte if m=0 (16-bit memory/accumulator)
- 65816: Add 1 cycle if m=0 (16-bit memory/accumulator)
- 65816: Add 1 cycle if low byte of Direct Page register is not 0
- Add 1 cycle if adding index crosses a page boundary
Last modified November 5, 2021: Add instruction categories (6b74ff9)