Is that right ?Įdit : Hey, you actually is the guy who take all those pictures of each SNES card in his possesion ? Great job. So, even if Star Ocean is considered as LoROM and Tales of Phantasia as HiROM, this makes no differance since both are both types. So the game is half HiROM and half LoROM. I think it should be the first 32 Megabits are mapped normally, and the last 16 Megabits are mapped into $00-$3f : $8000-$7ffff in 32kB chunks. Does it uses the $0000-$7ffff space in some manner or is it just mapped as a HiROM ?Īlso, doccuments doesn't say how HiROM games above 32 Megabits are mapped. I think Star Ocean is considered as a LoROM by emulators, but it should be an exeption, because it uses a special chip. This is the mirror of the normal ROM that there is at $8000-$ffff, right ?Īlso, since banks $70-$7d (or $e0-$ed) are entierly reserved for SRAM, my conclusions are that the maximum size for a LoROM game is of $70 banks of 32kB, wich is 28 Megabits (I never saw any above 24 Megabits). Some docs says that without MAD-1 chip, there is data at bank $40-$6f (or $c0-$ef) $0000-$7ffff. I'm unsure how LoROMs greather than 16 Megabit are mapped. I think the data to be battery backed is inside the big special chip, called ST-OTO. It has a battery, but no SRAM ! It is found in Exhaus Heat II, I don't have that game but I found it here. My Super Mario Kart have no MAD chip on it. ![]() I'm not hurried to code something for those chips or anything, but a little more info would be welcome. Since both SNES9x and ZSNES emulates most of the special chips correctly, I think there *is* people arround that know how they works. I also havent found more doccumentations on those special chips than list of them with short description of their feature and example of games using the chips. I'd first undertand 100% how regular cartridges works. It also increase the complexity of the cart circuitry, since you have to do additionnal adress decoding to enable/disable chips. Since SNES chips aren't EPROM, but mask ROMs, and they were made some time ago, I can undertand that it was another story.īut logically, you have the same amound of silicium, but if you made two small chips, you need more plastic, more pins, etc. 2x16 is cheaper than 1x32, it's like that for everything (ram, usb keys, various cards).Ĭommon EPROMs hardly go over 8 Megabits, but the common EPROMs aren't twice as expensive as the EPROM with the half of memory in it. Does the board circuitry varies in function of the speed of the ROM chip ? I'm almost sure it doesn't, but again, this isn't doccumented. Why LoRom mapping is refered as "Mode 20" and HiRom as "Mode 21" ? Is there a known difference between board names ending with 'B', 'M' and 'N' ? Is there a known difference between board names begining with '2', 'B', 'L' and 'Y' ? I think Tactics Ogre actually has a 32 megabit chip, but the last 8 megabit is never adressed/empty. But this is confirmed to be wrong, since my Tactics Ogre cart (24 megabit) has only one chip, and my Donkey Kong Country cart (32 megabit) has two chips ! I would think that it was to get intermediate ROM sizes that aren't power of 2 in size, like 12 meabit being 8+4, 24 megabit being 16+8, etc. Why some games have more than one ROM chip ? Having one big ROM chip is surely cheaper than have two small ones, and this rather complicate the board circuitry. 'M' is here for games with the MAD-1 chip in them, and the games that don't have either 'B' or 'N'. I havent figured exactly what means the fourth symbol. The third symbol is related to SRAM size. Other letters are for games using custom chips. The second symbol obviously indicate the ROM mapping type, so 'A' means LoRom and 'J' means HiRom. ![]() The symbol choosen seems to vary in function of the overal size of both ROM chips, but I'm not sure. Sometimes there is 2 ROM chips, so either 'B', 'L', 'Y' or '2' is written as the first symbol. There most often is one, so the number '1' is written. The first symbol indicate the number of ROM chips. ![]() When you open any cartridge and watch its board name, there are 4 symbols (letters or numbers) that follows "SHVC-" that will teach attribute about the cart type : There are doccuments covering SNES memory mapping, but not really SNES cart types (even if it is related, it isn't exactly the same). ![]() I found no doccument related to that stuff, and I figured out what is below by myself. I wonder a bit about the cart types of the SNES. Hi, I hope I post this to the right place.
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