STA (STore Accumulator)¶

[operand] = A

The STA instruction transfers the contents of the accumulator register (A) to the specified memory location. The operand specifies the memory location where the data is to be stored.

Addressing Modes¶

Mode	Syntax	Bytes	Cycles
ZeroPage	STA zp	`85 nn`	3
ZeroPage+X	STA zp,x	`95 nn`	4
Absolute	STA addr	`8D ll hh`	4
Absolute+X	STA addr,x	`9D ll hh`	5
Absolute+Y	STA addr,y	`99 ll hh`	5
(Indirect+X)	STA (zp,x)	`81 nn`	6
(Indirect)+Y	STA (zp),y	`91 nn`	6

Flags Affected¶

None.

Examples¶

Storing a Value to a Memory Location¶

    LDA #10     ; load A with constant 10
    STA $40     ; store the value of A to memory location $40

Storing the Accumulator to an Absolute Address¶

    STA $2000   ; store the value of A to memory location $2000

Storing the Accumulator to a Zero-Page Address¶

    STA $40     ; store the value of A to memory location $40

Storing the Accumulator to an Address Indexed by X¶

    LDA #10     ; load A with constant 10
    LDX #2      ; load X with constant 2
    STA $40,X   ; store the value of A to memory location $42 (assuming X = 2)