We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS
LDY: Difference between revisions
From SnesLab
(clobbered -> affected) |
(dp alignment penalty) |
||
Line 10: | Line 10: | ||
|A0 | |A0 | ||
|2 bytes | |2 bytes | ||
|2 cycles | |2 cycles* | ||
|+ | |+ | ||
|absolute | |absolute | ||
|AC | |AC | ||
|3 bytes | |3 bytes | ||
|4 cycles | |4 cycles* | ||
|+ | |+ | ||
|direct page | |direct page | ||
|A4 | |A4 | ||
|2 bytes | |2 bytes | ||
|3 cycles | |3 cycles* | ||
|+ | |+ | ||
|absolute indexed X | |absolute indexed X | ||
|BC | |BC | ||
|3 bytes | |3 bytes | ||
|4 cycles | |4 cycles* | ||
|+ | |+ | ||
|direct page indexed X | |direct page indexed X | ||
|B4 | |B4 | ||
|2 bytes | |2 bytes | ||
|4 cycles | |4 cycles* | ||
|} | |} | ||
Line 55: | Line 55: | ||
|} | |} | ||
'''LDY''' (Load Y) is a 65x instruction that loads the [[Y index register]]. | '''LDY''' (Load Y) is a 65x instruction that loads the [[Y index register]]. In [[direct page addressing]] modes, LDY takes another extra cycle if the low byte of the [[direct page register]] is nonzero. | ||
=== See Also === | === See Also === |
Revision as of 01:18, 20 November 2023
Basic Info | |||||||
---|---|---|---|---|---|---|---|
Addressing Mode | Opcode | Length | Speed | ||||
immediate | A0 | 2 bytes | 2 cycles* | ||||
absolute | AC | 3 bytes | 4 cycles* | ||||
direct page | A4 | 2 bytes | 3 cycles* | ||||
absolute indexed X | BC | 3 bytes | 4 cycles* | ||||
direct page indexed X | B4 | 2 bytes | 4 cycles* |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . | . |
LDY (Load Y) is a 65x instruction that loads the Y index register. In direct page addressing modes, LDY takes another extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page on LDY: https://archive.org/details/0893037893ProgrammingThe65816/page/n489
- Labiak page on LDY: https://archive.org/details/Programming_the_65816/page/n161
- MCS6500 Manual page on LDY: https://archive.org/details/mos_microcomputers_programming_manual/page/n114
- Carr page on LDY: https://archive.org/details/6502UsersManual/page/n277
- Leventhal page on LDY: https://archive.org/details/6502-assembly-language-programming/page/n123
- snes9x implementation of LDY: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L817
- undisbeliever on LDY: https://undisbeliever.net/snesdev/65816-opcodes.html#ldy-load-index-register-y-from-memory