I found this page a while back: SEGA Saturn cartridge port pinouts
It seems that some of the signals are still unknown? I unsoldered an ST-Key recently which contained a PAL and a rom. Unsurprisingly the PAL is not readable, but I got a dump of the rom (I think... it didn't want to read correctly as the device which it is labeled as). I'm thinking about getting a 27C1024 to replace it and run my own test code, then I can put a scope on the PAL signals.
Also, there were Saturn schematics on a Japanese site, but I could not determine where the cartridge port lines lead to.
It seems that some of the signals are still unknown? I unsoldered an ST-Key recently which contained a PAL and a rom. Unsurprisingly the PAL is not readable, but I got a dump of the rom (I think... it didn't want to read correctly as the device which it is labeled as). I'm thinking about getting a 27C1024 to replace it and run my own test code, then I can put a scope on the PAL signals.
Also, there were Saturn schematics on a Japanese site, but I could not determine where the cartridge port lines lead to.