# 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).

<div class="description" id="bkmrk-1985-copyright-on-pc">- 1985 copyright on PCB
- VRAM and WRAM are NDIP-only
- 3193 Non-A CIC

</div>#### **NES-CPU-03**

<div class="description" id="bkmrk-unreleased">- Unreleased

</div>#### **NES-CPU-04 - 2A03E/2C02E-0**

<div class="description" id="bkmrk-1986-copyright-on-pc">- 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

</div>#### **NES-CPU-05 - 2A03G/2C02G-0**

<div class="description" id="bkmrk-1986-copyright-on-pc-1">- 1986 copyright on PCB
- VRAM and WRAM are NDIP-only
- 3193A CIC

</div>#### **NES-CPU-06 - 2A03G/2C02G-0**

<div class="description" id="bkmrk-1987-copyright-on-pc">- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>#### **NES-CPU-07 - 2A03G/2C02G-0**

<div class="description" id="bkmrk-1987-copyright-on-pc-1">- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>#### **NES-CPU-08 - 2A03G/2C02G-0**

<div class="description" id="bkmrk-1989-copyright-on-pc">- 1989 copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>#### **NES-CPU-09 - 2A03G/2C02G-0 or 2A07/2C07-0**

<div class="description" id="bkmrk-1987-copyright-on-pc-2">- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>Has one resistor between CIC pin and cart connector to prevent CIC stun attacks

#### **NES-CPU-10 - 2A03G/2C02G**

<div class="description" id="bkmrk-1987-copyright-on-pc-3">- 1987 copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>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\[A\]** 

<div class="description" id="bkmrk-1987-copyright-on-pc-4">- 1987 Copyright on PCB
- VRAM and WRAM are NDIP or DIP

</div>Has two resistors and two diodes between CIC pins, cart connector and GND to prevent CIC stun and -5V attacks