Does anyone here know a lot about PlayStation 1 mod chips?
I took my old PS1 apart and found the mod chip that was installed back then.
The PS1 has a PU-22 motherboard, and a PIC12C508/P is soldered onto it. The chip is glued into the case and soldered to the motherboard with wires.
If I’ve identified the pins correctly, pins 2, 3, and 5 are not in use.
I’m trying to figure out exactly which firmware or mod this might be.
The chip number provides you most of this information, but it's just a programmable IC chip used by many different mod code sets.
https://quade.co/ps1-modchip-guide/
https://www.youtube.com/watch?v=Zx3UOFS6woU
https://www.reddit.com/r/psx/comments/10n4u3c/what_type_of_mod_chip_is_this_and_is_it_a_good_one/
https://www.psx-place.com/threads/ps1-mod-chip.25652/
To be more helpful, specifically, since you probably found some of that already: This is not a "stealth" mod chip, but a pretty basic "play burned / imported games" chip that later titles could circumvent. Whether it's wired correctly...eeehhh...I'd say chuck a burned/different region disc in the drive and see what happens? Can't hurt and that's probably a faster way of testing if you have such handy. If you don't then you'd need some burned games regardless if you're going to make use of that chip, regardless.
I will say that's a fuckton of extra wire length and is likely not doing the chip any favors. Some of those solder blobs are excessive, too. If you intend to keep it, bare minimum I would do some cleanup on those wires and the soldering job in general if you're comfortable with that work. Minimum required run lengths, etc. One of the reddit links below, using blue wires, has a better example though there are others that are even tighter and use breakout boards for a bit cleaner look.
I can't see under that heat/RF shield in your picture, but all the diagrams for your board and that chip - provided on specifically their instruction sets - do not align with anything "modern." The Quade link only has diagrams for Mayumi, a single MultiMode version, Onechip, and PsNee, and it's definitely none of those.
In particular, 5 wires would seem to align with the non-stealth Old Crow modchip code and you can't do anything about it as those chips a write-once only.
https://www.reddit.com/r/psx/comments/1h426jf/help_me_identify_this_modchip/
https://www.reddit.com/r/psx/comments/1h0jew0/what_is_that/
Either this fits your needs / the chip is functioning as you'd like, or you will want to remove the chip and install a newer one.
There is no way to be "sure" as to what firmware is on that chip without an EPROM reader/burner; up to you if you want to go through the hassle, but in my opinion it doesn't really matter particularly if it's working and if it's not you'd need a new one anyway.
You cannot "upgrade" the chip to a different instruction set / turn it into a stealth chip with some extra wires and a re-flash for the same write-once issue mentioned.
