CPU pinout: Difference between revisions
From NESdev Wiki
Jump to navigationJump to search
(took information from the talk page and incorporated.) |
(reflect that TST has not in fact yet been publicly tested) |
||
| Line 55: | Line 55: | ||
* /NMI and /IRQ are the two interrupt pins. See the 6502 manual for more detailed explanation. | * /NMI and /IRQ are the two interrupt pins. See the 6502 manual for more detailed explanation. | ||
* M2 can be considered as a "signals ready" pin. It is a modified version the 6502's φ2 that allow for slower ROMs. | * M2 can be considered as a "signals ready" pin. It is a modified version the 6502's φ2 that allow for slower ROMs. | ||
* TST (tentative name) (pin 30) is special: normally it is grounded in the NES, Famicom, PC10/VS. NES and other Nintendo Arcade Boards (Popeye and Donkey Kong 3) | * TST (tentative name) (pin 30) is special: normally it is grounded in the NES, Famicom, PC10/VS. NES and other Nintendo Arcade Boards (Popeye and Donkey Kong 3). It is conjectured that if it is pulled high, extra diagnostic registers to test the sound hardware are enabled from $4018 through $401A, and reading the joystick ports $4016 and $4017 is disabled. | ||
Revision as of 22:19, 14 September 2011
Pin out
| AD1 - 01 | 40 - +5V |
| AD2 - 02 | 39 - OUT0 |
| /RST - 03 | 38 - OUT1 |
| A00 - 04 | 37 - OUT2 |
| A01 - 05 | 36 - /OE1 |
| A02 - 06 | 35 - /OE2 |
| A03 - 07 | 34 - R/W |
| A04 - 08 | 33 - NMI |
| A05 - 09 | 32 - /IRQ |
| A06 - 10 | 31 - M2 |
| A07 - 11 | 30 - TST (usually GND) |
| A08 - 12 | 29 - CLK |
| A09 - 13 | 28 - D0 |
| A10 - 14 | 27 - D1 |
| A11 - 15 | 26 - D2 |
| A12 - 16 | 25 - D3 |
| A13 - 17 | 24 - D4 |
| A14 - 18 | 23 - D5 |
| A15 - 19 | 22 - D6 |
| GND - 20 | 21 - D7 |
Signal description
Active-Low signals are indicated by a "/".
- CLK is the 21.47727 MHz (NTSC) or 26.6017 MHz (PAL) clock input. Internally, the real clock (φ0) is derived by dividing the input clock frequency by 12 (NTSC 2A03) or 16 (PAL 2A07).
- AD1 (both pulse waves) and AD2 (triangle, noise, and DPCM) are the Audio Out pins.
- Axx is the address bus and Dx the data bus.
- OUT0-OUT2 are output pins used by the controllers ($4016 output latch bits 0-2). These 3 pins are connected to the expansion port pins 43-45, and OUT0 is additionally used as the "strobe" signal (OUT) on both controller ports.
- /OE1 and /OE2 also go to the controller ports, and each enable the output of their respective controller, if present.
- R/W is the read/write signal, which is used to indicate operations of the same names. Low is write.
- /NMI and /IRQ are the two interrupt pins. See the 6502 manual for more detailed explanation.
- M2 can be considered as a "signals ready" pin. It is a modified version the 6502's φ2 that allow for slower ROMs.
- TST (tentative name) (pin 30) is special: normally it is grounded in the NES, Famicom, PC10/VS. NES and other Nintendo Arcade Boards (Popeye and Donkey Kong 3). It is conjectured that if it is pulled high, extra diagnostic registers to test the sound hardware are enabled from $4018 through $401A, and reading the joystick ports $4016 and $4017 is disabled.
