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A project log for NES Motherboard

Motherboard schematic for the original Nintendo Entertainment System

jesse-robinson-beaconJesse Robinson (beacon) 11/17/2016 at 03:140 Comments

Completed netting of all pins attached to IC's U1 - U10. Questionable assignments on a few pins though, would like review some more.

Nintendo's custom 48-pin expansion header has been replaced with a 50 pin ribbon cable connector.

The CIC chip is present but not wired to the CPU's reset line. Currently the CIC host reset line is wired to expansion pin 49.

The following pins are not connected to anything:

U3: 6,7,10,12

U10: 5

P2: 46,50

Now on to the circuits with passive components......

TO DO:

Circuits:

Reset Switch

Power switch

System Clock

CIC Clock

CPU Analog Audio IN/OUT

PPU Analog Video OUT

Joypad pullup resistor banks

Joypad diode banks

Joypad connectors

misc pull resistors,caps

AV line level output circuits

usb power in

Other:

famicom io ports

fork schematic,replace ram with sourceable chips, update pinout

look for cheaper/smaller/modern components

....this could take awhile

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