6502 Instruction Set

LO-BYTE

BRK impl

ORA X,ind

??? ---

ORA zpg

ASL zpg

??? ---

PHP impl

ORA #

ASL A

??? ---

ORA abs

ASL abs

??? ---

BPL rel

ORA ind,Y

??? ---

ORA zpg,X

ASL zpg,X

??? ---

CLC impl

ORA abs,Y

??? ---

ORA abs,X

ASL abs,X

??? ---

JSR abs

AND X,ind

??? ---

BIT zpg

AND zpg

ROL zpg

??? ---

PLP impl

AND #

ROL A

??? ---

BIT abs

AND abs

ROL abs

??? ---

BMI rel

AND ind,Y

??? ---

AND zpg,X

ROL zpg,X

??? ---

SEC impl

AND abs,Y

??? ---

AND abs,X

ROL abs,X

??? ---

RTI impl

EOR X,ind

??? ---

EOR zpg

LSR zpg

??? ---

PHA impl

EOR #

LSR A

??? ---

JMP abs

EOR abs

LSR abs

??? ---

BVC rel

EOR ind,Y

??? ---

EOR zpg,X

LSR zpg,X

??? ---

CLI impl

EOR abs,Y

??? ---

EOR abs,X

LSR abs,X

??? ---

RTS impl

ADC X,ind

??? ---

ADC zpg

ROR zpg

??? ---

PLA impl

ADC #

ROR A

??? ---

JMP ind

ADC abs

ROR abs

??? ---

BVS rel

ADC ind,Y

??? ---

ADC zpg,X

ROR zpg,X

??? ---

SEI impl

ADC abs,Y

??? ---

ADC abs,X

ROR abs,X

??? ---

STA X,ind

??? ---

STY zpg

STA zpg

STX zpg

??? ---

DEY impl

??? ---

TXA impl

??? ---

STY abs

STA abs

STX abs

??? ---

BCC rel

STA ind,Y

??? ---

STY zpg,X

STA zpg,X

STX zpg,Y

??? ---

TYA impl

STA abs,Y

TXS impl

??? ---

STA abs,X

??? ---

LDY #

LDA X,ind

LDX #

??? ---

LDY zpg

LDA zpg

LDX zpg

??? ---

TAY impl

LDA #

TAX impl

??? ---

LDY abs

LDA abs

LDX abs

??? ---

BCS rel

LDA ind,Y

??? ---

LDY zpg,X

LDA zpg,X

LDX zpg,Y

??? ---

CLV impl

LDA abs,Y

TSX impl

??? ---

LDY abs,X

LDA abs,X

LDX abs,Y

??? ---

CPY #

CMP X,ind

??? ---

CPY zpg

CMP zpg

DEC zpg

??? ---

INY impl

CMP #

DEX impl

??? ---

CPY abs

CMP abs

DEC abs

??? ---

BNE rel

CMP ind,Y

??? ---

CMP zpg,X

DEC zpg,X

??? ---

CLD impl

CMP abs,Y

??? ---

CMP abs,X

DEC abs,X

??? ---

CPX #

SBC X,ind

??? ---

CPX zpg

SBC zpg

INC zpg

??? ---

INX impl

SBC #

NOP impl

??? ---

CPX abs

SBC abs

INC abs

??? ---

BEQ rel

SBC ind,Y

??? ---

SBC zpg,X

INC zpg,X

??? ---

SED impl

SBC abs,Y

??? ---

SBC abs,X

INC abs,X

??? ---

Address Modes:

A	....	Accumulator	OPC A	operand is AC
abs	....	absolute	OPC $HHLL	operand is address $HHLL
abs,X	....	absolute, X-indexed	OPC $HHLL,X	operand is address incremented by X with carry
abs,Y	....	absolute, Y-indexed	OPC $HHLL,Y	operand is address incremented by Y with carry
#	....	immediate	OPC #$BB	operand is byte (BB)
impl	....	implied	OPC	operand implied
ind	....	indirect	OPC ($HHLL)	operand is effective address; effective address is value of address
X,ind	....	X-indexed, indirect	OPC ($BB,X)	operand is effective zeropage address; effective address is byte (BB) incremented by X without carry
ind,Y	....	indirect, Y-indexed	OPC ($LL),Y	operand is effective address incremented by Y with carry; effective address is word at zeropage address
rel	....	relative	OPC $BB	branch target is PC + offset (BB), bit 7 signifies negative offset
zpg	....	zeropage	OPC $LL	operand is of address; address hibyte = zero ($00xx)
zpg,X	....	zeropage, X-indexed	OPC $LL,X	operand is address incremented by X; address hibyte = zero ($00xx); no page transition
zpg,Y	....	zeropage, Y-indexed	OPC $LL,Y	operand is address incremented by Y; address hibyte = zero ($00xx); no page transition

Instructions by Name:

ADC	....	add with carry
AND	....	and (with accumulator)
ASL	....	arithmetic shift left
BCC	....	branch on carry clear
BCS	....	branch on carry set
BEQ	....	branch on equal (zero set)
BIT	....	bit test
BMI	....	branch on minus (negative set)
BNE	....	branch on not equal (zero clear)
BPL	....	branch on plus (negative clear)
BRK	....	interrupt
BVC	....	branch on overflow clear
BVS	....	branch on overflow set
CLC	....	clear carry
CLD	....	clear decimal
CLI	....	clear interrupt disable
CLV	....	clear overflow
CMP	....	compare (with accumulator)
CPX	....	compare with X
CPY	....	compare with Y
DEC	....	decrement
DEX	....	decrement X
DEY	....	decrement Y
EOR	....	exclusive or (with accumulator)
INC	....	increment
INX	....	increment X
INY	....	increment Y
JMP	....	jump
JSR	....	jump subroutine
LDA	....	load accumulator
LDY	....	load X
LDY	....	load Y
LSR	....	logical shift right
NOP	....	no operation
ORA	....	or with accumulator
PHA	....	push accumulator
PHP	....	push processor status (SR)
PLA	....	pull accumulator
PLP	....	pull processor status (SR)
ROL	....	rotate left
ROR	....	rotate right
RTI	....	return from interrupt
RTS	....	return from subroutine
SBC	....	subtract with carry
SEC	....	set carry
SED	....	set decimal
SEI	....	set interrupt disable
STA	....	store accumulator
STX	....	store X
STY	....	store Y
TAX	....	transfer accumulator to X
TAY	....	transfer accumulator to Y
TSX	....	transfer stack pointer to X
TXA	....	transfer X to accumulator
TXS	....	transfer X to stack pointer
TYA	....	transfer Y to accumulator

Registers:

PC	....	program counter	(16 bit)
AC	....	accumulator	(8 bit)
X	....	X register	(8 bit)
Y	....	Y register	(8 bit)
SR	....	status register [NV-BDIZC]	(8 bit)
SP	....	stack pointer	(8 bit)

SR Flags (bit 7 to bit 0):

N	....	Negative
V	....	Overflow
-	....	ignored
B	....	Break
D	....	Decimal (use BCD for arithmetics)
I	....	Interrupt (IRQ disable)
Z	....	Zero
C	....	Carry

Processor Stack:
LIFO, top down, 8 bit range, 0x0100 - 0x01FF

Bytes, Words, Addressing:
8 bit bytes, 16 bit words in lobyte-hibyte representation (Little-Endian).
16 bit address range, operands follow instruction codes.

Vendor:
MOS Technology, 1975

APPENDIX A: 6502 Instructions in Detail ADC Add Memory to Accumulator with Carry A + M + C -> A, C N Z C I D V + + + - - + addressing assembler opc bytes cyles -------------------------------------------- immidiate ADC #oper 69 2 2 zeropage ADC oper 65 2 3 zeropage,X ADC oper,X 75 2 4 absolute ADC oper 6D 3 4 absolute,X ADC oper,X 7D 3 4* absolute,Y ADC oper,Y 79 3 4* (indirect,X) ADC (oper,X) 61 2 6 (indirect),Y ADC (oper),Y 71 2 5* AND AND Memory with Accumulator A AND M -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate AND #oper 29 2 2 zeropage AND oper 25 2 3 zeropage,X AND oper,X 35 2 4 absolute AND oper 2D 3 4 absolute,X AND oper,X 3D 3 4* absolute,Y AND oper,Y 39 3 4* (indirect,X) AND (oper,X) 21 2 6 (indirect),Y AND (oper),Y 31 2 5* ASL Shift Left One Bit (Memory or Accumulator) C <- [76543210] <- 0 N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- accumulator ASL A 0A 1 2 zeropage ASL oper 06 2 5 zeropage,X ASL oper,X 16 2 6 absolute ASL oper 0E 3 6 absolute,X ASL oper,X 1E 3 7 BCC Branch on Carry Clear branch on C = 0 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BCC oper 90 2 2** BCS Branch on Carry Set branch on C = 1 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BCS oper B0 2 2** BEQ Branch on Result Zero branch on Z = 1 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BEQ oper F0 2 2** BIT Test Bits in Memory with Accumulator bits 7 and 6 of operand are transfered to bit 7 and 6 of SR (N,V); the zeroflag is set to the result of operand AND accumulator. A AND M, M7 -> N, M6 -> V N Z C I D V M7 + - - - M6 addressing assembler opc bytes cyles -------------------------------------------- zeropage BIT oper 24 2 3 absolute BIT oper 2C 3 4 BMI Branch on Result Minus branch on N = 1 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BMI oper 30 2 2** BNE Branch on Result not Zero branch on Z = 0 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BNE oper D0 2 2** BPL Branch on Result Plus branch on N = 0 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BPL oper 10 2 2** BRK Force Break interrupt, N Z C I D V push PC+2, push SR - - - 1 - - addressing assembler opc bytes cyles -------------------------------------------- implied BRK 00 1 7 BVC Branch on Overflow Clear branch on V = 0 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BVC oper 50 2 2** BVS Branch on Overflow Set branch on V = 1 N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- relative BVC oper 70 2 2** CLC Clear Carry Flag 0 -> C N Z C I D V - - 0 - - - addressing assembler opc bytes cyles -------------------------------------------- implied CLC 18 1 2 CLD Clear Decimal Mode 0 -> D N Z C I D V - - - - 0 - addressing assembler opc bytes cyles -------------------------------------------- implied CLD D8 1 2 CLI Clear Interrupt Disable Bit 0 -> I N Z C I D V - - - 0 - - addressing assembler opc bytes cyles -------------------------------------------- implied CLI 58 1 2 CLV Clear Overflow Flag 0 -> V N Z C I D V - - - - - 0 addressing assembler opc bytes cyles -------------------------------------------- implied CLV B8 1 2 CMP Compare Memory with Accumulator A - M N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate CMP #oper C9 2 2 zeropage CMP oper C5 2 3 zeropage,X CMP oper,X D5 2 4 absolute CMP oper CD 3 4 absolute,X CMP oper,X DD 3 4* absolute,Y CMP oper,Y D9 3 4* (indirect,X) CMP (oper,X) C1 2 6 (indirect),Y CMP (oper),Y D1 2 5* CPX Compare Memory and Index X X - M N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate CPX #oper E0 2 2 zeropage CPX oper E4 2 3 absolute CPX oper EC 3 4 CPY Compare Memory and Index Y Y - M N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate CPY #oper C0 2 2 zeropage CPY oper C4 2 3 absolute CPY oper CC 3 4 DEC Decrement Memory by One M - 1 -> M N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- zeropage DEC oper C6 2 5 zeropage,X DEC oper,X D6 2 6 absolute DEC oper CE 3 3 absolute,X DEC oper,X DE 3 7 DEX Decrement Index X by One X - 1 -> X N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied DEC CA 1 2 DEY Decrement Index Y by One Y - 1 -> Y N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied DEC 88 1 2 EOR Exclusive-OR Memory with Accumulator A EOR M -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate EOR #oper 49 2 2 zeropage EOR oper 45 2 3 zeropage,X EOR oper,X 55 2 4 absolute EOR oper 4D 3 4 absolute,X EOR oper,X 5D 3 4* absolute,Y EOR oper,Y 59 3 4* (indirect,X) EOR (oper,X) 41 2 6 (indirect),Y EOR (oper),Y 51 2 5* INC Increment Memory by One M + 1 -> M N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- zeropage INC oper E6 2 5 zeropage,X INC oper,X F6 2 6 absolute INC oper EE 3 6 absolute,X INC oper,X FE 3 7 INX Increment Index X by One X + 1 -> X N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied INX E8 1 2 INY Increment Index Y by One Y + 1 -> Y N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied INY C8 1 2 JMP Jump to New Location (PC+1) -> PCL N Z C I D V (PC+2) -> PCH - - - - - - addressing assembler opc bytes cyles -------------------------------------------- absolute JMP oper 4C 3 3 indirect JMP (oper) 6C 3 5 JSR Jump to New Location Saving Return Address push (PC+2), N Z C I D V (PC+1) -> PCL - - - - - - (PC+2) -> PCH addressing assembler opc bytes cyles -------------------------------------------- absolute JSR oper 20 3 6 LDA Load Accumulator with Memory M -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate LDA #oper A9 2 2 zeropage LDA oper A5 2 3 zeropage,X LDA oper,X B5 2 4 absolute LDA oper AD 3 4 absolute,X LDA oper,X BD 3 4* absolute,Y LDA oper,Y B9 3 4* (indirect,X) LDA (oper,X) A1 2 6 (indirect),Y LDA (oper),Y B1 2 5* LDX Load Index X with Memory M -> X N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate LDX #oper A2 2 2 zeropage LDX oper A6 2 3 zeropage,Y LDX oper,Y B6 2 4 absolute LDX oper AE 3 4 absolute,Y LDX oper,Y BE 3 4* LDY Load Index Y with Memory M -> Y N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate LDY #oper A0 2 2 zeropage LDY oper A4 2 3 zeropage,X LDY oper,X B4 2 4 absolute LDY oper AC 3 4 absolute,X LDY oper,X BC 3 4* LSR Shift One Bit Right (Memory or Accumulator) 0 -> [76543210] -> C N Z C I D V - + + - - - addressing assembler opc bytes cyles -------------------------------------------- accumulator LSR A 4A 1 2 zeropage LSR oper 46 2 5 zeropage,X LSR oper,X 56 2 6 absolute LSR oper 4E 3 6 absolute,X LSR oper,X 5E 3 7 NOP No Operation --- N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- implied NOP EA 1 2 ORA OR Memory with Accumulator A OR M -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- immidiate ORA #oper 09 2 2 zeropage ORA oper 05 2 3 zeropage,X ORA oper,X 15 2 4 absolute ORA oper 0D 3 4 absolute,X ORA oper,X 1D 3 4* absolute,Y ORA oper,Y 19 3 4* (indirect,X) ORA (oper,X) 01 2 6 (indirect),Y ORA (oper),Y 11 2 5* PHA Push Accumulator on Stack push A N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- implied PHA 48 1 3 PHP Push Processor Status on Stack push SR N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- implied PHP 08 1 3 PLA Pull Accumulator from Stack pull A N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- implied PLA 68 1 4 PLP Pull Processor Status from Stack pull SR N Z C I D V from stack addressing assembler opc bytes cyles -------------------------------------------- implied PHP 28 1 4 ROL Rotate One Bit Left (Memory or Accumulator) C <- [76543210] <- C N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- accumulator ROL A 2A 1 2 zeropage ROL oper 26 2 5 zeropage,X ROL oper,X 36 2 6 absolute ROL oper 2E 3 6 absolute,X ROL oper,X 3E 3 7 ROR Rotate One Bit Right (Memory or Accumulator) C -> [76543210] -> C N Z C I D V + + + - - - addressing assembler opc bytes cyles -------------------------------------------- accumulator ROR A 6A 1 2 zeropage ROR oper 66 2 5 zeropage,X ROR oper,X 76 2 6 absolute ROR oper 6E 3 6 absolute,X ROR oper,X 7E 3 7 RTI Return from Interrupt pull SR, pull PC N Z C I D V from stack addressing assembler opc bytes cyles -------------------------------------------- implied RTI 40 1 6 RTS Return from Subroutine pull PC, PC+1 -> PC N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- implied RTS 60 1 6 SBC Subtract Memory from Accumulator with Borrow A - M - C -> A N Z C I D V + + + - - + addressing assembler opc bytes cyles -------------------------------------------- immidiate SBC #oper E9 2 2 zeropage SBC oper E5 2 3 zeropage,X SBC oper,X F5 2 4 absolute SBC oper ED 3 4 absolute,X SBC oper,X FD 3 4* absolute,Y SBC oper,Y F9 3 4* (indirect,X) SBC (oper,X) E1 2 6 (indirect),Y SBC (oper),Y F1 2 5* SEC Set Carry Flag 1 -> C N Z C I D V - - 1 - - - addressing assembler opc bytes cyles -------------------------------------------- implied SEC 38 1 2 SED Set Decimal Flag 1 -> D N Z C I D V - - - - 1 - addressing assembler opc bytes cyles -------------------------------------------- implied SED F8 1 2 SEI Set Interrupt Disable Status 1 -> I N Z C I D V - - - 1 - - addressing assembler opc bytes cyles -------------------------------------------- implied SEI 78 1 2 STA Store Accumulator in Memory A -> M N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- zeropage STA oper 85 2 3 zeropage,X STA oper,X 95 2 4 absolute STA oper 8D 3 4 absolute,X STA oper,X 9D 3 5 absolute,Y STA oper,Y 99 3 5 (indirect,X) STA (oper,X) 81 2 6 (indirect),Y STA (oper),Y 91 2 6 STX Store Index X in Memory X -> M N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- zeropage STX oper 86 2 3 zeropage,Y STX oper,Y 96 2 4 absolute STX oper 8E 3 4 STY Sore Index Y in Memory Y -> M N Z C I D V - - - - - - addressing assembler opc bytes cyles -------------------------------------------- zeropage STY oper 84 2 3 zeropage,X STY oper,X 94 2 4 absolute STY oper 8C 3 4 TAX Transfer Accumulator to Index X A -> X N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TAX AA 1 2 TAY Transfer Accumulator to Index Y A -> Y N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TAY A8 1 2 TSX Transfer Stack Pointer to Index X SP -> X N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TSX BA 1 2 TXA Transfer Index X to Accumulator X -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TXA 8A 1 2 TXS Transfer Index X to Stack Register X -> SP N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TXS 9A 1 2 TYA Transfer Index Y to Accumulator Y -> A N Z C I D V + + - - - - addressing assembler opc bytes cyles -------------------------------------------- implied TYA 98 1 2 * add 1 to cycles if page boundery is crossed ** add 1 to cycles if branch occurs on same page add 2 to cycles if branch occurs to different page Legend to Flags: + .... modified - .... not modified 1 .... set 0 .... cleared M6 .... memory bit 6 M7 .... memory bit 7 Note on assembler syntax: Most assemblers employ "OPC *oper" for forced zeropage addressing. APENDIX B: The 65xx-Family: Type Features, Comments ------------------------------------- 6502 NMOS, 16 bit address bus, 8 bit data bus 6502A accelerated version of 6502 6502C accelerated version of 6502, CMOS 65C02 16 bit version, additional instructions and address modes 6503, 6505, 6506 12 bit address bus [4 KiB] 6504 13 bit address bus [8 KiB] 6507 13 bit address bus [8 KiB], no interrupts 6509 20 bit address bus [1 MiB] by bankswitching 6510 as 6502 with additional 6 bit I/O-port 6511 integrated micro controler with I/O-port, serial interface, and RAM (Rockwell) 65F11 as 6511, integrated FORTH interpreter 7501 as 6502, HMOS 8500 as 6510, CMOS 8502 as 6510 with switchable 2 MHz option, 7 bit I/O-port 65816 (65C816) 16 bit registers and ALU, 24 bit address bus [16 MiB], up to 24 MHz (Western Design Center) 65802 (65C802) as 65816, pin compatible to 6502, 64 KiB address bus, up to 16 MHz

Disclaimer:
Errors excepted. The information is provided for free and AS IS, therefore without any warranty;
without even the implied warranty of merchantability or fitness for a particular purpose.

The official 65xx Website (The Western Design Center Inc.): www.65xx.com

See also:
>> Virtual 6502 (6502/6510 emulator)
>> 6502 Assembler
>> 6502 Disassembler

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