go6502/docs/6502.org

• References
• Reset sequences
  • Reset/interrupt vectors
• Misc references
• Timing
  • cc = 01
  • cc = 10
  • cc = 00
• Opcodes remaining

References

• Detailed per-instruction timing, etc: http://www.masswerk.at/6502/6502_instruction_set.html
• aaabbbcc-type breakdown: http://www.llx.com/~nparker/a2/opcodes.html
• 6502 Hardware manual (KIM-1): http://users.telenet.be/kim1-6502/6502/hwman.html#AA
• For doublechecking cycle counts: http://www.obelisk.demon.co.uk/6502/reference.html
• Stack explanation (annoying writing): http://homepage.ntlworld.com/cyborgsystems/CS_Main/6502/6502.htm#STACK

Reset sequences

• http://www.pagetable.com/?p=410

Reset/interrupt vectors

Address	Description
$FFFE/F	IRQ
$FFFA/B	NMI
$FFFC/D	Reset

Misc references

• http://axis.llx.com/~nparker/a2/opcodes.html

Timing

aaabbbcc

cc = 01

aaa	opcode	flags
000	ORA	NZ
001	AND	NZ
010	EOR	NZ
011	ADC	NZCV
100	STA
101	LDA	NZ
110	CMP	NZC
111	SBC	NZCV

bbb	addressing mode
000	(zero page,X)
001	zero page
010	#immediate
011	absolute
100	(zero page),Y
101	zero page,X
110	absolute,Y
111	absolute,X

Addressing Mode	ORA		AND		EOR		ADC		STA		LDA		CMP		SBC
(zp,X)	01	2/6	21	2/6	41	2/6	61	2/6	81	2/6	A1	2/6	C1	2/6	E1	2/6
zp	05	2/3	25	2/3	45	2/3	65	2/3	85	2/3	A5	2/3	C5	2/3	E5	2/3
#	09	2/2	29	2/2	49	2/2	69	2/2			A9	2/2	C9	2/2	E9	2/2
abs	0D	3/4	2D	3/4	4D	3/4	6D	3/4	8D	3/4	AD	3/4	CD	3/4	ED	3/4
(zp),Y	11	2/5*	31	2/5*	51	2/5*	71	2/5*	91	2/6	B1	2/5*	D1	2/5*	F1	2/5*
zp,X	15	2/4	35	2/4	55	2/4	75	2/4	95	2/4	B5	2/4	D5	2/4	F5	2/4
abs,Y	19	3/4*	39	3/4*	59	3/4*	79	3/4*	99	3/5	B9	3/4*	D9	3/4*	F9	3/4*
abs,X	1D	3/4*	3D	3/4*	5D	3/4*	7D	3/4*	9D	3/5	BD	3/4*	DD	3/4*	FD	3/4*

(*) - add 1 to cycles if page boundary is crossed

cc = 10

aaa	opcode	flags
000	ASL	NZC
001	ROL	NZC
010	LSR	NZC
011	ROR	NZC
100	STX
101	LDX	NZ
110	DEC	NZ
111	INC	NZ

bbb	addressing mode
000	#immediate
001	zero page
010	accumulator
011	absolute
101	zero page,X	STX,LDX: zero page, Y
111	absolute,X	LDX: absolute,Y

	ASL		ROL		LSR		ROR		STX		LDX		DEC		INC
#											A2	2/2
zp	06	2/5	26	2/5	46	2/5	66	2/5	86	2/3	A6	2/3	C6	2/5	E6	2/5
A	0A	1/2	2A	1/2	4A	1/2	6A	1/2
abs	0E	3/6	2E	3/6	4E	3/6	6E	3/6	8E	3/4	AE	3/4	CE	3/6	EE	3/6
zp,X/zp,Y	16	2/6	36	2/6	56	2/6	76	2/6	96	2/4	B6	2/4	D6	2/6	F6	2/6
abs,X/abs,Y	1E	3/7	3E	3/7	5E	3/7	7E	3/7	??		BE	3/4*	DE	3/7	FE	3/7

(*) - add 1 to cycles if page boundary is crossed

cc = 00

aaa	opcode	flags
001	BIT	NZV
010	JMP
011	JMP (abs)
100	STY
101	LDY
110	CPY	NZC
111	CPX	NZC

bbb	addressing mode
000	#immediate
001	zero page
011	absolute
101	zero page,X
111	absolute,X

	BIT		JMP		JMP()		STY		LDY		CPY		CPX
#									A0	2/2	C0	2/2	E0	2/2
zp	24	2/3					84	2/3	A4	2/3	C4	2/3	E4	2/3
abs	2C	3/4	4C	3/3	6C	3/5	8C	3/4	AC	3/4	CC	3/4	EC	3/4
zp,X							94	2/4	B4	2/4
abs,X									BC	3/4*

Opcodes remaining

	00	01	02	03	04	05	06	07	08	09	0A	0B	0C	0D	0E	0F
00			-	-	-			-				-	-			-
10			-	-	-			-			-	-	-	ORA abs,X	ASL abs,X	-
20			-	-				-				-				-
30			-	-	-			-			-	-	-	AND abs,X	ROL abs,X	-
40			-	-	-			-				-				-
50			-	-	-			-			-	-	-	EOR abs,X	LSR abs,X	-
60			-	-	-			-				-				-
70			-	-	-			-			-	-	-	ADC abs,X	ROR abs,X	-
80	-		-	-				-		-		-				-
90			-	-				-				-	-		-	-
A0				-				-				-				-
B0			-	-				-				-	LDY abs,X	LDA abs,X	LDX abs,Y	-
C0			-	-				-				-				-
D0			-	-	-			-			-	-	-	CMP abs,X	DEC abs,X	-
E0		SBC X,ind	-	-		SBC zpg		-	INX impl	SBC #		-		SBC abs		-
F0			-	-	-	SBC zpg,X		-		SBC abs,Y	-	-	-	SBC abs,X	INC abs,X	??? -