While reading nesdev wiki, i found some info about this feature of VRC2.
IIRC RC828 and RC823 have traces for unknown DIP-8 chip, connected to pin 16->4, 17->3,18->2,19->1 respectively. No idea, if this ability of VRC2 ever used, or maybe there is just patched code in those titles.
krzy is very welcome to this thread for discussion.
Never had any original VRC2 game so can't confirm if the EPROM interface work properly in it, but I tested many DIP40 VRC2 clones and the EPROM interface worked exactly as described on the wiki:
Pinout (which is same for original & clones) is here:
I wouldn't be surprised if the clones were 100% compatible with original. For example VRC4 pin 18 is never used anywhere chip enable for register $9003 which is also present in the clone.
There are a few pirate games (port from different mappers) which contain VRC2 clone and EEPROM, for example:
Dragon Ball Z2 / Dragon Ball Z3: https://forums.nesdev.com/viewtopic.php?f=9&t=16955
Dragon Ball Z: https://forums.nesdev.com/viewtopic.php?f=9&t=18496 - this one needs IRQ (so they used VRC4 clone, but it does not have EPROM interface, so they wired external components to "add" the missing EEPROM interface:
No idea what is this one, but has 2 EEPROMS: https://forums.nesdev.com/viewtopic.php?f=9&t=16662
Thanks for respond.
QuoteNever had any original VRC2 game so can't confirm if the EPROM interface work properly in it...
Calling japanese resident members(i'm not there at moment) to help krzy
with couple cheap VRC2/4 based games. C'mon, guys ;D
Thanks for the hardware pr0n :o those ridiculous pirate carts. I always wondering, who was behind their circuitry.
So the saving game feature is working in those carts and they utilizing original code, only bank switching patched?
By the way, PAL/GAL in PLCC is quite common thing. Anything else? ::)