Arakon...about your mega cd bios chips
- Thread starter jimmy_s
- Start date
It's quite simple; the "expansion port" is almost identical to the cartridge slot, as far as the presence and behavior of main signals go (the main cart slot has a bunch of stuff that almost never gets used). When the MD runs the BIOS, it pretty much sees the ROM as it would any cart ROM. Put a game there instead of a BIOS program, and it runs the game.
It can be done, but it was Columns for a reason - putting three BIOS images on a single ROM leaves a fourth of the ROM unused. Since it's a 4Mb ROM, that leaves a big 1Mb for the game. There aren't many 1Mb MD games (fewer than ten I think, and presumably most of them aren't that great). Using a bigger ROM would require soldering additional connections, and would waste more of the ROM. An SMS game can't be done because the M3/SMS mode pin isn't available at the expansion slot, and you'd be limited in your selection there too because SMS games bigger than 48KB require a mapper chip.
hey arakon, any chance when i order this thing i can get another rom burned with some games on it? the rare ones are so hard to find now. People just either sell their consoles with all their games or bin the carts now. All second hand shops no longer take in megadrive games. Will etch myself a board with all the roms on and wire a big ass rotary switch to control it
