Note

Although there are two hundred and fifty-six po33ible eight-bit opcodes, many of the possibilities are not used by the 6502. If one of these unused values is accidentally included in a program, unpredictable (often bad) results will occur.

3.H.1 Memory Transfer Instructions

All of the following instructions either copy ("Load") the contents of a memory location into a register or copy ("Store") the contents of a

Name Description

LDA Load the accumulator with the contents of the specified memory location

STA Store the accumulator into the specified memory location

LDX Load the X index register with the contents of the specified memory location

STX Store the X index register into the specified memory location

LDY Load the Y index register with the contents of the specified memory location

STY Store the Y index register into the specified memory location

The opcodes for each memory-transfer instruction with each of its possible addressing modes are a3 follows:

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