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TDC: Difference between revisions
From SnesLab
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!colspan="8"|Flags | !colspan="8"|Flags Affected | ||
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|[[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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|N | |N | ||
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'''TDC''' (Transfer Direct page register to aCcumulator) is a [[65c816]] instruction that transfers the value of the [[direct page register]] to the 16-bit [[accumulator]]. | '''TDC''' (Transfer Direct page register to aCcumulator) is a [[65c816]] instruction that transfers the value of the [[direct page register]] to the 16-bit [[accumulator]]. An alternate mnemonic is "TDA." | ||
TDC ignores the [[m flag]] and always transfers 16 bits, even in [[6502 emulation mode]]. | |||
==== Syntax ==== | |||
<pre> | |||
TDC | |||
TDA | |||
</pre> | |||
TDC is a good way to zero the [[accumulator]], but only works when the direct page has not be relocated, of course. | |||
=== See Also === | === See Also === | ||
* [[TCD]] | * [[TCD]] | ||
* [[PHD]] | |||
* [[PLD]] | |||
* [[XBA]] | |||
=== External Links === | === External Links === | ||
* [[Eyes & Lichty]] | * [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/512 page 512] on TDC | ||
* [[Labiak]] | * [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n203 page 193] on TDC | ||
* snes9x implementation of TDC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2337 | * snes9x implementation of TDC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2337 | ||
* Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.10.2 | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:65c816 additions]] | [[Category:65c816 additions]] | ||
[[Category:Transfer Instructions]] | |||
[[Category:One-byte Instructions]] | |||
[[Category:Implied Instructions]] | |||
[[Category:Two-cycle Instructions]] | |||
Latest revision as of 00:30, 10 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Implied (type 1) | 7B | 1 byte | 2 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C |
| N | . | . | . | . | . | Z | . |
TDC (Transfer Direct page register to aCcumulator) is a 65c816 instruction that transfers the value of the direct page register to the 16-bit accumulator. An alternate mnemonic is "TDA."
TDC ignores the m flag and always transfers 16 bits, even in 6502 emulation mode.
Syntax
TDC TDA
TDC is a good way to zero the accumulator, but only works when the direct page has not be relocated, of course.
See Also
External Links
- Eyes & Lichty, page 512 on TDC
- Labiak, page 193 on TDC
- snes9x implementation of TDC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2337
- Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.10.2