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TDC: Difference between revisions
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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]]. An alternate mnemonic is "TDA." | '''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 | TDC ignores the [[m flag]] and always transfers 16 bits, even in [[6502 emulation mode]]. | ||
==== Syntax ==== | ==== Syntax ==== | ||
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TDA | TDA | ||
</pre> | </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 === | ||
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=== 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 | * Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.10.2 | ||
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