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LDX: Difference between revisions
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'''LDX''' (Load X) is a 65x instruction that loads the [[X index register]]. | {| class="wikitable" style="float:right;clear:right;width:40%" | ||
!colspan="8"|Basic Info | |||
|+ | |||
|'''Addressing Mode''' | |||
|'''Opcode''' | |||
|'''Length''' | |||
|'''Speed''' | |||
|+ | |||
|[[Immediate]] | |||
|A2 | |||
|2 bytes* | |||
|2 cycles* | |||
|+ | |||
|[[Absolute]] | |||
|AE | |||
|3 bytes | |||
|4 cycles* | |||
|+ | |||
|[[Direct Page Addressing|Direct Page]] | |||
|A6 | |||
|2 bytes | |||
|3 cycles* | |||
|+ | |||
|absolute indexed Y | |||
|BE | |||
|3 bytes | |||
|4 cycles* | |||
|+ | |||
|direct page indexed Y | |||
|B6 | |||
|2 bytes | |||
|4 cycles* | |||
|} | |||
{| class="wikitable" style="float:right;clear:right;width:30%" | |||
!colspan="9"|Flags Affected | |||
|+ | |||
|[[Negative Flag|N]] | |||
|[[Overflow Flag|V]] | |||
|[[M Flag|M]] | |||
|[[X Flag|X]] | |||
|[[Decimal Flag|D]] | |||
|[[I Flag|I]] | |||
|[[Zero Flag|Z]] | |||
|[[Carry Flag|C]] | |||
|+ | |||
| | |||
|. | |||
|. | |||
|. | |||
|. | |||
|. | |||
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|. | |||
|} | |||
'''LDX''' (Load X) is a 65x instruction that loads the [[X index register]]. In [[immediate addressing]] only, LDX is a total of 3 bytes long when the index registers are 16 bits wide. | |||
===== Cycle Penalties ===== | |||
* In [[direct page addressing]] modes, LDX takes another extra cycle if the low byte of the [[direct page register]] is nonzero. | |||
* | |||
* | |||
=== See Also === | === See Also === | ||
* [[STX]] | |||
* [[LDA]] | * [[LDA]] | ||
* [[LDY]] | * [[LDY]] | ||
=== External Links === | |||
* [[Eyes & Lichty]] page 463, on LDX: https://archive.org/details/0893037893ProgrammingThe65816/page/n489 | |||
* [[Labiak]] page 150 on LDX: https://archive.org/details/Programming_the_65816/page/n160 | |||
* [[MCS6500 Manual]] page 96 on LDX: https://archive.org/details/mos_microcomputers_programming_manual/page/n114 | |||
* https://archive.org/details/mos_microcomputers_programming_manual/page/n219, lbid. | |||
* [[Carr]] page 264 on LDX: https://archive.org/details/6502UsersManual/page/n277 | |||
* [[Leventhal]] page 3-72 on LDX: https://archive.org/details/6502-assembly-language-programming/page/n121 | |||
* snes9x implementation of LDX: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L772 | |||
* undisbeliever on LDX: https://undisbeliever.net/snesdev/65816-opcodes.html#ldx-load-index-register-x-from-memory | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Group Two Instructions]] | |||
[[Category:Inherited from 6502]] | |||
[[Category:Load/Store Instructions]] |
Latest revision as of 21:57, 9 January 2024
Basic Info | |||||||
---|---|---|---|---|---|---|---|
Addressing Mode | Opcode | Length | Speed | ||||
Immediate | A2 | 2 bytes* | 2 cycles* | ||||
Absolute | AE | 3 bytes | 4 cycles* | ||||
Direct Page | A6 | 2 bytes | 3 cycles* | ||||
absolute indexed Y | BE | 3 bytes | 4 cycles* | ||||
direct page indexed Y | B6 | 2 bytes | 4 cycles* |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . | . |
LDX (Load X) is a 65x instruction that loads the X index register. In immediate addressing only, LDX is a total of 3 bytes long when the index registers are 16 bits wide.
Cycle Penalties
- In direct page addressing modes, LDX takes another extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page 463, on LDX: https://archive.org/details/0893037893ProgrammingThe65816/page/n489
- Labiak page 150 on LDX: https://archive.org/details/Programming_the_65816/page/n160
- MCS6500 Manual page 96 on LDX: https://archive.org/details/mos_microcomputers_programming_manual/page/n114
- https://archive.org/details/mos_microcomputers_programming_manual/page/n219, lbid.
- Carr page 264 on LDX: https://archive.org/details/6502UsersManual/page/n277
- Leventhal page 3-72 on LDX: https://archive.org/details/6502-assembly-language-programming/page/n121
- snes9x implementation of LDX: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L772
- undisbeliever on LDX: https://undisbeliever.net/snesdev/65816-opcodes.html#ldx-load-index-register-x-from-memory