Splitting the Atom

page 72

Appendix 3. 6502 Assembler and Machine code

MNEMONIC

ABS

ABS, X

ZP, X

IMM

(IND, X)

ABS, Y

(IND), Y

ACC.

ZP, Y

(IND)

ORA

Logic
and math

AND

EOR

ADC

STA

LDA

CMP

SBC

ASL

Shift and
Rotate

ROL

LSR

ROR

DEC

Dec/Inc
Acc.

INC

LDY

Load / Store
index regs

LDX

STY

STX

CPX

Compare
index regs

CPY

BIT

Bit test

JMP

Program flow

JSR

Branches

MNEMONIC	REL
BPL	10	Branches
BMI	30
BVC	50
BVS	70
BCC	90
BCS	B0
BNE	D0
BEQ	F0
BRN	80	Branch Never (6502 undocumented)
BRA	80	Branch Always (65C02)

Implied

MNEMONIC	IMP.
DEX	CA	Dec/Inc index regs
DEY	88
INX	E8
INY	C8
PHA	48	Stack ops
PHP	08
PLA	68
PLP	28
RTI	40	Return
RTS	60	Return
TAX	AA	Register transfers
TAY	A8
TSX	BA
TXA	8A
TXS	9A
TYA	98
CLC	18	Clear / Set flags
SEC	38
CLD	D8
SED	F8
CLI	58
SEI	78
CLV	B8
BRK	00
NOP	EA

Erratum: Original text said EOR POST,Y = NONE. This is not true.

6502 Op Codes (for disassembly)

\ LSD MSD \ 0 1 2 3 4 5 6 7 8 9 A B C D E F LSD / / MSD

0 BRK ORA (IND,X) JAM SRA (IND,X) NOP ZP ORA ZP ASL ZP SRA ZP PHP ORA IMM ASL A ANC IMM NOP ABS ORA ABS ASL ABS SRA ABS 0

1 BPL ORA (IND),Y JAM SRA (IND),Y NOP ZP,X ORA ZP,X ASL ZP,X SRA ZP,X CLC ORA ABS,Y NOP SRA ABS,Y NOP ABS,X ORA ABS,X ASL ABS,X SRA ABS,X 1

2 JSR ABS AND (IND,X) JAM RLA (IND,X) BIT ZP AND ZP ROL ZP RLA ZP PLP AND IMM ROL A ANC IMM BIT ABS AND ABS ROL ABS RLA ABS 2

3 BMI AND (IND),Y JAM RLA (IND),Y NOP ZP,X AND ZP,X ROL ZP,X RLA ZP,X SEC AND ABS,Y NOP RLA ABS,Y NOP ABS,X AND ABS,X ROL ABS,X RLA ABS,X 3

4 RTI EOR (IND,X) JAM SLO (IND,X) NOP ZP EOR ZP LSR ZP SLO ZP PHA EOR IMM LSR A ASR IMM JMP ABS EOR ABS LSR ABS SLO ABS 4

5 BVC EOR (IND),Y JAM SLO (IND),Y NOP ZP,X EOR ZP,X LSR ZP,X SLO ZP,X CLI EOR ABS,Y NOP SLO ABS,Y NOP ABS,X EOR ABS,X LSR ABS,X SLO ABS,X 5

6 RTS ADC (IND,X) JAM RRA (IND,X) NOP ZP ADC ZP ROR ZP RRA ZP PLA ADC IMM ROR A ARR IMM JMP Indirect ADC ABS ROR ABS RRA ABS 6

7 BVS ADC (IND),Y JAM RRA (IND),Y NOP ZP,X ADC ZP,X ROR ZP,X RRA ZP,X SEI ADC ABS,Y NOP RRA ABS,Y NOP ABS,X ADC ABS,X ROR ABS,X RRA ABS,X 7

8 STA (IND,X) NOP IMM SAX (IND,X) STY ZP STA ZP STX ZP SAX ZP DEY NOP IMM TXA AXE IMM STY ABS STA ABS STX ABS SAX ABS 8

9 BCC STA (IND),Y JAM AX7 (IND),Y STY ZP,X STA ZP,X STX ZP,Y SAX ZP,Y TYA STA ABS,Y TXS XS7 ABS,Y SY7 ABS,X STA ABS,X SX7 ABS,Y AX7 ABS,Y 9

A LDY IMM LDA (IND,X) LDX IMM LAX (IND,X) LDY ZP LDA ZP LDX ZP LAX ZP TAY LDA IMM TAX XEA IMM LDY ABS LDA ABS LDX ABS LAX ABS A

B BCS LDA (IND),Y JAM LAX (IND),Y LDY ZP,X LDA ZP,X LDX ZP,Y LAX ZP,Y CLV LDA ABS,Y TSX LAS ABS,Y LDY ABS,X LDA ABS,X LDX ABS,Y LAX ABS,Y B

C CPY IMM CMP (IND,X) NOP IMM DCP (IND,X) CPY ZP CMP ZP DEC ZP DCP ZP INY CMP IMM DEX ASX IMM CPY ABS CMP ABS DEC ABS DCP ABS C

D BNE CMP (IND),Y JAM DCP (IND),Y NOP ZP,X CMP ZP,X DEC ZP,X DCP ZP,X CLD CMP ABS,Y NOP DCP ABS,Y NOP ABS,X CMP ABS,X DEC ABS,X DCP ABS,X D

E CPX IMM SBC (IND,X) NOP IMM ISB (IND,X) CPX ZP SBC ZP INC ZP ISB ZP INX SBC IMM NOP SBC IMM CPX ABS SBC ABS INC ABS ISB ABS E

F BEQ SBC (IND),Y JAM ISB (IND),Y NOP ZP,X SBC ZP,X INC ZP,X ISB ZP,X SED SBC ABS,Y NOP ISB ABS,Y NOP ABS,X SBC ABS,X INC ABS,X ISB ABS,X F

MSD / / LSD 0 1 2 3 4 5 6 7 8 9 A B C D E F \ MSD LSD \