Mainboard Revisions (NTSC)
PCB revisions run from NES-CPU-01 to -11. Revisions below -05 will have noticeably poorer video output than later revisions. Revisions -10 and -11 use circuitry to try to defeat the lockout defeaters of the unlicensed cartridges.
NES-CPU-02 - 2A03E/2C02E-0
The original US release of the NES (fewer than 10,000 were made).
- 1985 copyright on PCB
- VRAM and WRAM are NDIP-only
- 3193 Non-A CIC
NES-CPU-03
- Unreleased
NES-CPU-04 - 2A03E/2C02E-0
- 1986 copyright on PCB
- VRAM and WRAM are NDIP-only
- 3193 Non-A or 3193A CIC
- some have a 74HC139 at U3 instead of 74LS139
NES-CPU-05 - 2A03G/2C02G-0
- 1986 copyright on PCB
- VRAM and WRAM are NDIP-only
- 3193A CIC
NES-CPU-06 - 2A03G/2C02G-0
- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP
NES-CPU-07 - 2A03G/2C02G-0
- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP
NES-CPU-08 - 2A03G/2C02G-0
- 1989 copyright on PCB
- VRAM and WRAM are NDIP or DIP
NES-CPU-09 - 2A03G/2C02G-0 or 2A07/2C07-0
- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP
Has one resistor between CIC pin and cart connector to prevent CIC stun attacks
NES-CPU-10 - 2A03G/2C02G
- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP
Has two resistors between CIC pins and cart connector to thwart more CIC voltage stun, some later revisions have a diode to nearby GND vias as well to prevent the -5V attack
NES-CPU-11 - 2A03G/2C02G or 2A07[A]/2C07[A]
- 1987 Copyright on PCB
- VRAM and WRAM are NDIP or DIP
Has two resistors and two diodes between CIC pins, cart connector and GND to prevent CIC stun and -5V attacks
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