tepples wrote:
The Famicom PPU is identical to the NTSC NES PPU.
Right'o. You can put the RGB PPU in any Famicom or NES, as the PPU is pin compatible between the following:
HVC-001 - the original Famicom
HVC-101 - the New Famicom (A/V)
NES-001 - the original ‘toaster’ NES
NES-101 - the NES2 'top-loader'
AN-500 - Sharp Twin Famicom
AN-505 - Sharp Twin Famicom II
Famicombox
Sharp 19" NES TV
AN-510 - Sharp Video Titler
C1 series from Sharp
VS. System Arcades
Playchoice-10 Arcades
Some (non-NOAC) clones; Dendy comes to mind.
There are some differences though... The AN-510, Sharp C1, Playchoice and VS. Systems all have RGB PPUs, as may the Sharp NES TV for the US market,, however VS. System PPUs have differing colour sets to prevent easy piracy.
Very early HVC-001 PPUs have a design flaw that makes them unreliable, and it's possible that early PPUs will have trouble with some mappers.
As I recall, the NES-101 PPU also has glitches that cause video errors and make A/V output problematic.
Also note that a handful of games don't run on the RGB PPU, so you may want to consider wiring both an RGB and an NTSC Composite PPC in series, on a daughterboard with selector switches.
That way, you have a fallback for non-RGB compliant games.
I wonder if any of the older clone system PPUs are RGB...
I never tried screwing around with them to find out.
It may also be possible to design an FPGA replacement PPU that handles RGB output *and* correctly handles the games that Sharp's chip doesn't like.
If you rip a chip from a VS. System, you can probably get it working too, but you’d need to be more creative.
Frankly, I think it’d be cooler idea to modify a Playchoice board to accept NES/FC carts. I should hunt down some PC and VS boards to muck around with and add a cart slot to them, inside a cabinet and make a PowerPak arcade.
Huzzah! One more project to attempt!
-Xious
Written on my Treo 700p in Blazer.