nesdev.org

I would like to present my home-made famicom with both PAL and NTSC support.
It has 2 CPUs: UA6527 (NTSC), UA6527P(PAL)
and 2 PPUS: UA6528 (NTSC), UA6538 (PAL).

It has 15pin/9pin/NES joypad connector and 60pin(famicom) and 72pin(NES) cart connector. The joypad connector has D3/D4 connected like in original NES so four score works!

The 2 layer PCB is projected from scratch in eagle and then home made etched.



Lets see the movie (I added english lyrics):
https://www.youtube.com/watch?v=bddG-z1qxho

Very impressive. Home etching is intimidating, so kudos on making it work. Having both the NTSC and PAL CPUs and PPUs on the same 2 layer board must have been a challenge to route!

I notice you simply use pins sticking out of the board for your NES controller sockets. In case you're looking for actual controller sockets, you could always cannibalize a couple of cheap NES extension cables.

How do you handle the bus multiplexing between the two PPUs?

I assume that with the CPUs, as with the 2A03, you can keep one or the other in high-impedance by asserting its /RST input?

CPU is well behaved - the unselected one is held in reset, so that A0-A15, R/!W, M2, OUT0-OUT2, PORT1_!OE, PORT2_!OE are in high ipedance state.

PPU is not so wel behaved so I installed under the extra mini-pcb with 2 PPUs four buffers (74hc245) and one 74hc125 buffer. They put in high impedance state AD0-AD7,A9-A13 for each ppu. The unselected ppu is held in reset and also !CE is held 1 constantly so that D0-D7 (pin2-9) is high impedance.

Hello!
Long time lurker, first time poster

I was building similar thing, both NTSC and PAL CPU/PPU, and i found this thread.
I'm trying to piggypack original NTSC CPU with 6527P(PAL dendy)
I'll work on PPU once i have got the CPU sorted.

The crystal/cpu/ppu swap works as expected, but i tried to piggyback the CPU, with unselected chip reset held low, but it did'nt work. NTSC-mode works partly, with many glitches, and PAL brings only colored screen. (or other way around, i disassembled it already, can't remember).

Any advice?

Cool project!

Is there any particular software you use to make those chip labels?

Thats impressive.