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CPY: Difference between revisions

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'''CPY''' (Compare Y) is a 65x instruction that compares the value of the [[Y index register]].  Internally, this is done via a subtraction, but the difference is not stored anywhere.
'''CPY''' (Compare Y) is a 65x instruction that compares the value of the [[Y index register]].  Internally, this is done via a subtraction, but the difference is not stored anywhere.  The contents at the effective address and the Y index register both remain unchanged.


=== See Also ===
=== See Also ===

Revision as of 02:54, 19 December 2023

Basic Info
Addressing Mode Opcode Length Speed
Immediate C0 2 bytes* 2 cycles*
Absolute CC 3 bytes 4 cycles*
Direct Page C4 2 bytes 3 cycles*
Flags Affected
N V M X D I Z C
. . . . .

CPY (Compare Y) is a 65x instruction that compares the value of the Y index register. Internally, this is done via a subtraction, but the difference is not stored anywhere. The contents at the effective address and the Y index register both remain unchanged.

See Also

External Links

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