6502 Instruction Summary
RTK, last update: 23-Jul-97
Summary format:
--------------
mnemonic - instruction name
operation processor status flags affected
assembler format opcode
--------------------------------------------------------------------------------
ADC - Add to Accumulator with Carry
=====================================
A+M+C -> A,C N, Z, C, V
ADC #aa 69
ADC aa 65
ADC aa,X 75
ADC aaaa 6D
ADC aaaa,X 7D
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AND - AND Memory with Accumulator
===================================
A and M -> A N, Z
AND #aa 29
AND aa 25
AND aa,X 35
AND aaaa 2D
AND aaaa,X 3D
AND aaaa,Y 39
AND (aa,X) 21
AND (aa),Y 31
--------------------------------------------------------------------------------
ASL - Accumulator Shift Left (also memory)
=============================================
+-+-+-+-+-+-+-+-+
C <- |7|6|5|4|3|2|1|0| <- 0 N, Z, C
+-+-+-+-+-+-+-+-+
ASL A 0A
ASL aa 06
ASL aa,X 16
ASL aaaa 0E
ASL aaaa,X 1E
--------------------------------------------------------------------------------
BCC - Branch on Carry Clear
=============================
branch on C=0 no flags
BCC aa 90
--------------------------------------------------------------------------------
BCS - Branch on Carry Set
===========================
branch on C=1 no flags
BCS aa B0
--------------------------------------------------------------------------------
BEQ - Branch Zero Set
=======================
branch on Z=1 no flags
BEQ aa F0
--------------------------------------------------------------------------------
BIT - Test Bits in Memory with Accumulator
============================================
A and M, M7 -> N, M6 -> V N=M7, V=M6, Z=1 if A and M = 0
neither A nor M are altered
BIT aa 24
BIT aaaa 2C
--------------------------------------------------------------------------------
BMI - Branch on Result Minus
==============================
branch on N=1 no flags
BMI aa 30
--------------------------------------------------------------------------------
BNE - Branch on Z reset
=============================
branch on Z=0 no flags
BNE aa D0
--------------------------------------------------------------------------------
BPL - Branch on Result Plus
=============================
branch on N=0 no flags
BPL aa 10
--------------------------------------------------------------------------------
BRK - Force a Break
=============================
forced interrupt B=1, I=1
BRK 00
--------------------------------------------------------------------------------
BVC - Branch on Overflow Clear
================================
branch on V=0 no flags
BVC aa 50
--------------------------------------------------------------------------------
BVS - Branch on Overflow Set
==============================
branch on V=1 no flags
BVS aa 70
--------------------------------------------------------------------------------
CLC - Clear Carry Flag
========================
0 -> C C=0
CLC 18
--------------------------------------------------------------------------------
CLD - Clear Decimal Mode
==========================
0 -> D D=0
CLD D8
CLI - Clear Interrupt Disable
===============================
0 -> I I=0
CLI 58
--------------------------------------------------------------------------------
CLV - Clear Overflow Flag
===========================
0 -> V V=0
CLV B8
--------------------------------------------------------------------------------
N.B. CMP, CPX, and CPY all set flags according to:
A, X, or Y < Memory ---> N=1, Z=0, C=0
A, X, or Y = Memory ---> N=0, Z=1, C=1
A, X, or Y > Memory ---> N=0, Z=0, C=1
CMP - Compare Memory and Accumulator
======================================
A compared with M N, Z, C
CMP #aa C9
CMP aa C5
CMP aa,X D5
CMP aaaa CD
CMP aaaa,X DD
CMP aaaa,Y D9
CMP (aa,X) C1
CMP (aa),Y D1
CPX - Compare Memory and X register
=====================================
X compared with M N, Z, C
CPX #aa E0
CPX aa E4
CPX aaaa EC
CPY - Compare Memory and Y register
=====================================
Y compare with M N, Z, C
CPY #aa C0
CPY aa C4
CPY aaaa CC
--------------------------------------------------------------------------------
DEC - Decrement Memory by One
===============================
M - 1 -> M N, Z
DEC aa C6
DEC aa,X D6
DEC aaaa CE
DEC aaaa,X DE
--------------------------------------------------------------------------------
DEX - Decrement X
===================
X - 1 -> X N, Z
DEX CA
--------------------------------------------------------------------------------
DEY - Decrement Y
===================
Y - 1 -> Y N, Z
DEY 88
--------------------------------------------------------------------------------
EOR - Exclusive-OR Memory with Accumulator
============================================
A xor M -> A N, Z
EOR #aa 49
EOR $aa 45
EOR $aa,X 55
EOR $aaaa 4D
EOR $aaaa,X 5D
EOR $aaaa,Y 59
EOR ($aa,X) 41
EOR ($aa),Y 51
--------------------------------------------------------------------------------
INC - Increment Memory by one
===============================
M + 1 -> M N, Z
INC $aa E6
INC $aa,X F6
INC $aaaa EE
INC $aaaa,X FE
--------------------------------------------------------------------------------
INX - Increment X by one
==========================
X + 1 -> X N, Z
INX E8
--------------------------------------------------------------------------------
INY - Increment Y by one
==========================
Y + 1 -> Y N, Z
INY C8
--------------------------------------------------------------------------------
JMP - Jump
============
JMP $aaaa 4C
JMP ($aaaa) 6C
--------------------------------------------------------------------------------
JSR - Jump to subroutine
==========================
JSR $aaaa 20
--------------------------------------------------------------------------------
LDA - Load Accumulator with memory
====================================
M -> A N, Z
LDA #aa A9
LDA $aa A5
LDA $aa,X B5
LDA $aaaa AD
LDA $aaaa,X BD
LDA $aaaa,Y B9
LDA ($aa,X) A1
LDA ($aa),Y B1
--------------------------------------------------------------------------------
LDX - Load X with Memory
==========================
M -> X N, Z
LDX #aa A2
LDX $aa A6
LDX $aa,Y B6
LDX $aaaa AE
LDX $aaaa,Y BE
--------------------------------------------------------------------------------
LDY - Load Y with Memory
==========================
M -> Y N, Z
LDY #aa A0
LDY $aa A4
LDY $aa,X B4
LDY $aaaa AC
LDY $aaaa,X BC
--------------------------------------------------------------------------------
LSR - Logical Shift Right
===========================
+-+-+-+-+-+-+-+-+
0 -> |7|6|5|4|3|2|1|0| -> C N, Z, C
+-+-+-+-+-+-+-+-+
LSR A 4A
LSR $aa 46
LSR $aa,X 56
LSR $aaaa 4E
LSR $aaaa,X 5E
--------------------------------------------------------------------------------
NOP - No Operation
====================
NOP EA
--------------------------------------------------------------------------------
ORA - OR Memory with Accumulator
==================================
A or M -> A N, Z
ORA #aa 09
ORA $aa 05
ORA $aa,X 15
ORA $aaaa 0D
ORA $aaaa,X 1D
ORA $aaaa,Y 19
ORA ($aa,X) 01
ORA ($aa),Y 11
--------------------------------------------------------------------------------
PHA - Push Accumulator on Stack
=================================
A -> Stack
PHA 48
--------------------------------------------------------------------------------
PHP - Push Processor Status on Stack
======================================
P -> Stack
PHP 08
--------------------------------------------------------------------------------
PLA - Pull Accumulator from Stack
===================================
Stack -> A N, Z
PLA 68
--------------------------------------------------------------------------------
PLP - Pull Processor Status from Stack
========================================
Stack -> P from stack
PLP 28
--------------------------------------------------------------------------------
ROL - Rotate Left
===================
+-+-+-+-+-+-+-+-+
C <- |7|6|5|4|3|2|1|0| <- C N, Z, C
+-+-+-+-+-+-+-+-+
ROL A 2A
ROL $aa 26
ROL $aa,X 36
ROL $aaaa 2E
ROL $aaaa,X 3E
--------------------------------------------------------------------------------
ROR - Rotate Right
====================
+-+-+-+-+-+-+-+-+
C -> |7|6|5|4|3|2|1|0| -> C N, Z, C
+-+-+-+-+-+-+-+-+
ROR A 6A
ROR $aa 66
ROR $aa,X 76
ROR $aaaa 6E
ROR $aaaa,X 7E
--------------------------------------------------------------------------------
RTI - Return from Interrupt
=============================
RTI 40
--------------------------------------------------------------------------------
RTS - Return from Subroutine
==============================
RTS 60
--------------------------------------------------------------------------------
SBC - Subtract from Accumulator with Carry
============================================
A - M - ~C -> A (~C is NOT C) N, Z, C, V
SBC #aa E9
SBC $aa E5
SBC $aa,X F5
SBC $aaaa ED
SBC $aaaa,X FD
SBC $aaaa,Y F9
SBC ($aa,X) E1
SBC ($aa),Y F1
--------------------------------------------------------------------------------
SEC - Set Carry Flag
======================
SEC 38
--------------------------------------------------------------------------------
SED - Set Decimal Mode
========================
SED F8
--------------------------------------------------------------------------------
SEI - Set Interrupt Disable
=============================
SEI 78
--------------------------------------------------------------------------------
STA - Store Accumulator in Memory
===================================
STA $aa 85
STA $aa,X 95
STA $aaaa 8D
STA $aaaa,X 9D
STA $aaaa,Y 99
STA ($aa,X) 81
STA ($aa),Y 91
--------------------------------------------------------------------------------
STX - Store X in Memory
=========================
STX $aa 86
STX $aa,Y 96
STX $aaaa 8E
--------------------------------------------------------------------------------
STY - Store Y in Memory
=========================
STY $aa 84
STY $aa,X 94
STY $aaaa 8C
--------------------------------------------------------------------------------
TAX - Transfer Accumulator to X
=================================
A -> X N, Z
TAX AA
--------------------------------------------------------------------------------
TAY - Transfer Accumulator to Y
=================================
A -> Y N, Z
TAY A8
--------------------------------------------------------------------------------
TSX - Transfer Stack to X
===========================
S -> X N, Z
TSX BA
--------------------------------------------------------------------------------
TXA - Transfer X to Accumulator
=================================
X -> A N, Z
TXA 8A
--------------------------------------------------------------------------------
TXS - Transfer X to Stack
===========================
X -> S N, Z
TXS 9A
--------------------------------------------------------------------------------
TYA - Transfer Y to Accumulator
=================================
Y -> A N, Z
TYA 98
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