As I comented to you in discord ygr is just lsi + sh1 join togeter in a single chip.
LSI is just hardware, imagine it like an non programable cpld or fpga, just logic, for glue all together.
I couldnt debug in yabause, in linux didnt work for me, I did a prety simple and slow sh1 emulator in...
Ive thinked about it and there is not a simple way for dump the rom. Or you got an Mode or a Satiator like slinga said or you need to setup all psy-q tools, code some kind of dumper and use scsi, or hotswap the cart, or using serial port.
Since some time ago I wanted to do something similar to zone66x, so based in his job Ive done my own serial saturn to usb cable.
If anyone interested I can upload pcb designs, also got some spare pcbs and components.
At the moment I use cable for uploading code to saturn, I needed it because...
Interchange proves and you will see positive voltage.
AC adapter is original??
Some voltage indication in FDD case??
Blue and green wires looks like main board power, have you measure voltage??
Looks like there is a voltage regulator after power input, can you take a better pic?
Ooook, im working on it, im searching for get netlink protocol working on pc side, once I get it, tcp/ip based conection should be trivial.
Just as curiosity, im also working in a serial to usb communication cable, ~9.5€, im waiting for pcbs and components.