Hey all, just wondering about this.
Id love to get into getting some PAL games, and was wondering if theres a way to mod the NES using a switch and PAL chips. Something along those lines of piggybacking all the chip legs and using a switch to determine what sets of chips to use. Is anything like this even remotely possible.
And please spare me the 'get a pal console' stuff, i would like to actually learn something whether how to do it IF its possible, or why it wouldn't work because of something i might not be aware of.
It's technically "possible", it's just very unlikely worth the effort.
Easier thing first: It's not too hard to put a 2A03 and 2A07 in the same system at the same time. BUT the 2A03 needs a 21.5MHz clock source and the 2A07 needs a 26.6MHz clock source. Whichever system is inactive MUST have its /RESET pin tied low.
Hard thing second: The 2C02 and 2C07 DO NOT have the same "disable all I/O drivers during reset" that the CPU has. You will have to add a multiplexer for every single output and bidirectional pin on the 2C02. Plus they still need different clocks.
Ahhh ok, thank you for the explanation!
lidnariq wrote:
It's technically "possible", it's just very unlikely worth the effort.
Easier thing first: It's not too hard to put a 2A03 and 2A07 in the same system at the same time. BUT the 2A03 needs a 21.5MHz clock source and the 2A07 needs a 26.6MHz clock source. Whichever system is inactive MUST have its /RESET pin tied low.
Hard thing second: The 2C02 and 2C07 DO NOT have the same "disable all I/O drivers during reset" that the CPU has. You will have to add a multiplexer for every single output and bidirectional pin on the 2C02. Plus they still need different clocks.
Oh and one last question, is it important to use the 2C07 WITH the 2A07? Does the CPU chip need something inside the PPU. Im not sure what else the PPU contains, aside from the color palette.
The PPU is responsible for emitting the correct video output. The CPU is responsible for the correct sound. Mixing and matching CPUs 2A03/2A07/UA6527P (Dendy) with non-matching PPUs (2C02/2C07/UA6538) will produce something that occupies a weird limbo of intermediate definitions. Simpler games will work, but anything that relies on the relative speed of the CPU and PPU won't.