NES CPU (NTSC) RP2A03G / RP2A03H By Eli Dayan _____ _____ | \_/ | SND1 - | 01 40 | - +5V (Vcc) SND2 - | 02 39 | - STROBE (joypad) /RST - | 03 38 | - EXT 44 A0 - | 04 37 | - EXT 45 A1 - | 05 36 | - /OE (joypad 0) A2 - | 06 35 | - /OE (joypad 1) A3 - | 07 34 | - R/W A4 - | 08 33 | - /NMI A5 - | 09 32 | - /IRQ A6 - | 10 31 | - M2 A7 - | 11 30 | - GND* A8 - | 12 29 | - CLK A9 - | 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 |_____________| Considerations: --------------- - there is NO decimal mode on the 2A03 - SND1 is the output for square waves 1 & 2. - SND2 is the output for triangle, noise, and DMC. - CLK is the NES master clock @ 21.47727 MHz - M2 is clocked at 1/2 the NTSC colorburst. This signal is divided (by 12) internally by the CPU and coincides with the CPU's clock speed of 1.7897725 MHz. - All memory access occurs when M2 is high (/CE is low on a ROM) - EXT 44 and EXT 45 connect to the expansion connector pins 44 and 45 respectively. - STROBE (joypad) is connected to STA $4016 D0 - /OE (joypads) is low during reads - GND* is tied low but may be the source of some signal EOF