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go6502/docs/6502.org
Zellyn Hunter 59a789746e Minor doc change
2013-02-27 23:19:48 -08:00

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* 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 | ??? - |
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