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TYA
From SnesLab
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Implied (type 1) | 98 | 1 byte | 2 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C |
| N | . | . | . | . | . | Z | . |
TYA is a 65x instruction that transfers the value of the Y index register to the accumulator. The size of the accumulator determines whether this is an 8 or 16 bit operation. TYA always takes two cycles, regardless of whether one or two bytes are transferred.
| Instruction Behavior | ||
|---|---|---|
| 8-bit accumulator (m=1) | 16-bit accumulator (m=0) | |
| 8-bit index registers (x=1) | 8 bits are transferred | 8 bits are transferred to the low byte of accumulator and high byte of the accumulator is zeroed |
| 16-bit index registers (x=0) | 8 bits (the low byte of the index register) are transferred and the hidden byte of the B accumulator is unaffected | 16 bits are transferred |
Syntax
TYA
See Also
External Links
- Eyes & Lichty, page 520 on TYA
- Labiak, page 201 on TYA
- 7.14 on MCS6500 Manual, page 101 on TYA
- Carr, page 275 on TYA
- Leventhal, page 3-104 on TYA
- snes9x implementation of TYA: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L2455