Hi guys, I've got a NTSC Model 1 837-6405 (no built in game) Master System. I tried replacing the BIOS with a hacked one from Console5.com but unfortunately, it causes my Master System to do absolutely nothing, so I wanna replace the BIOS. I tried out a couple different BIOS chips and I determined my favorite was the Japanese one due to the screen that displays when you insert it without a game, and I used Kega Fusion with a copy of this BIOS and then loaded a couple games from different regions and they all loaded fine. I'm certain that this isn't a perfect way to test it so that's why I'm posting here. So, my question is, can I get away with using a Japanese BIOS on a US console to play US games, or should I stick to a US console BIOS? Thanks.
I "made" a US boot ROM for my modded master system which uses the Japanese cartridge detection routine (no TMSS but it works fine at detecting if a cart is plugged). I have also a "mechanism" which latches the state of the pause and reset buttons on power up. Those define if the machine is to be DOMESTIC/EXPORT and if FM will be enabled. When in DOMESTIC mode the ROM is the JPN SMS one. When on Export mode the ROM is a "game less" SEGA bumper 1986 ROM (with TMSS code removed). Do you want to test it ?
