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LDA: Difference between revisions

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'''LDA''' (Load Accumulator) is a 65x instruction that loads the accumulator.  In all [[addressing modes]], LDA takes one extra cycle when the accumulator is 16 bits wide.  In [[direct page addressing]] modes, LDA takes another extra cycle if the low byte of the [[direct page register]] is nonzero.
'''LDA''' (Load Accumulator) is a 65x instruction that loads the accumulator.  In all [[addressing modes]], LDA takes one extra cycle when the accumulator is 16 bits wide.  In [[direct page addressing]] modes, LDA takes another extra cycle if the low byte of the [[direct page register]] is nonzero.  In both the [[Absolute Indexed]] and the DP Indirect Indexed by Y admodes, LDA takes an extra cycle if adding the index crosses a page boundary.


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

Revision as of 01:12, 20 November 2023

Basic Info
Addressing Mode Opcode Length Speed
immediate A9 2 bytes 2 cycles*
absolute AD 3 bytes 4 cycles*
absolute long AF 4 bytes 5 cycles*
direct page A5 2 bytes 3 cycles*
direct page indirect B2 2 bytes 5 cycles*
direct page indirect long A7 2 bytes 6 cycles*
absolute indexed by X BD 3 bytes 4 cycles*
absolute long indexed by X BF 4 bytes 5 cycles*
absolute indexed by Y B9 3 bytes 4 cycles*
direct page indexed by X B5 2 bytes 4 cycles*
direct page indexed indirect by X A1 2 bytes 6 cycles*
direct page indirect indexed by Y B1 2 bytes 5 cycles*
direct page indirect long indexed by Y B7 2 bytes 6 cycles*
stack relative A3 2 bytes 4 cycles*
stack relative indirect indexed by Y B3 2 bytes 7 cycles*
Flags Affected
N V M X D I Z C
. . . . . .

LDA (Load Accumulator) is a 65x instruction that loads the accumulator. In all addressing modes, LDA takes one extra cycle when the accumulator is 16 bits wide. In direct page addressing modes, LDA takes another extra cycle if the low byte of the direct page register is nonzero. In both the Absolute Indexed and the DP Indirect Indexed by Y admodes, LDA takes an extra cycle if adding the index crosses a page boundary.

See Also

External Links