TYA

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Transfer Y Index to Accumulator
Opcode: TYA
Operation: Y → A
Status Register: Status-List.png
Status-Change.pngStatus-Space.pngStatus-Change.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.pngStatus-Space.pngStatus-Ignore.png

TYA (Transfer Y Index to Accumulator) transfers the value in the Y index to the accumulator. The reverse of this opcode is TAY.

Operation

This pseudo C code shows how the TYA opcode functions when it is executed.

unsigned src = Y;             // Load the value of the Y index as an unsigned byte.
SET_NEGATIVE(src);            // Sets the Negative Flag equal to the 7th bit.
SET_ZERO(src);                // Sets the Zero Flag if the Operand is $#00, otherwise clears it.
A = (src);                    // Stores the value of the Y index into the accumulator.

Addressing Modes

Addressing Mode Assembly Language Form Opcode # Bytes # Cycles
Implied TYA 98 1 2

Examples