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Topic: Quickie question about Game Boy MBC5... (Read 662 times)
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Ryusui
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« on: April 19, 2007, 02:11:51 am » |
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Found a doc about the MBC5 online and discovered that max size for an MBC5 game is 64Mbits (8MB). This is accurate info, right?
I ask because, if I ever get around to attacking Sylvanian Families 2 - Rainbow Forest Fantasy, I'm probably gonna need some extra room. The game doesn't have nearly the copious amounts of blank space I used in SF1 to insert my script...
If the game is put together like the first one was - which I suspect is the case - all of the string pointers (and I do mean all of the string pointers) come with bank byte attached; this, seeing how the game is likely not designed to auto-switch banks above FF, means I could simply expand the ROM to 4MB and insert my script in the blank space, correct?
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Nightcrawler
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« Reply #1 on: April 19, 2007, 08:26:28 am » |
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I can't comment on MBC5, but the rest of what you've said is correct. If you've got a bank byte for every pointer, you can relocate the text to any free space in that addressable region without having to do much of anything.
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Tauwasser
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« Reply #2 on: April 19, 2007, 10:52:35 am » |
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Your info is not correct. Maximum size is still 4MB. Maximum for mbc3 is 2 MB. No 8MB games (because they are not addressable at all [00-FF --> 100 Banks --> 4 Mbytes]).
Also, notice how you lose RTC with mbc5, because only MBC3 can handle RTC. If you do replace the rtc, be sure to hack something up for the clock to work like intended (at least, while playing).
cYa,
Tauwasser
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Firlet
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« Reply #3 on: April 19, 2007, 12:09:56 pm » |
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Doc '12-Mar-98 by kOOPa' and 'GBcribsheet000129' mention 9-bits for MBC5 bank select (2000-2fff for lower 8-bits and 3000-3fff for upper 1-bit).
That's 4MB*2. Or is this mistaken? :confused:
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Ryusui
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« Reply #4 on: April 19, 2007, 01:28:32 pm » |
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The game is already MBC5 (it's the first GBC-only title in the series). The doc I found looked like an official Nintendo doc, and it said exactly what what Firlet just did: you can change the low byte by writing into $2000-$2FFF, and the high bit (bringing the highest addressable bank to 1FF) by writing into $3000-$3FFF. Granted, I suspect the game is not designed to auto-handle the higher banks, though an extra 2MB of space for script is always appreciated. :3 |
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Tauwasser
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« Reply #5 on: April 19, 2007, 05:11:37 pm » |
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Yeah, read about it. Well, I suspect it won't work though, because as far as I know, there is no official number for that big roms (and I've never seen one, too). I found out that 07 = 4MB and was happy with that, however, I doubt even many emulators support 08 (which would be equivalent to 8MB, goes in base 2 increases...). Maybe the gameboy really can handle that, but I doubt many emulators would. As far as I know they at least do depend on that.
If the spec really is that way, yes, it indeed does look like it can handle 8MB, sorry for my misconception there... However, you have to change the bank loading routine for that one (or, make two of them, one for all of the old stuff which loads bit0 3xxx with 0, and a newer one with settable bit0).
cYa,
Tauwasser
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KingMike
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« Reply #6 on: April 20, 2007, 09:26:19 am » |
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Might be as good a place as any to ask... is there a minimum size for GBC games? 'cause I'm just really curious Pong: The Next Level. Why on earth would they use 8 mbits of ROM when less than 1 mbit is actual data? Is there a minimum, or did Hasbro just want to blow money buying ROMs 3 sizes bigger than neccessary?  Um... and I see Nightcrawler just put the Transcorp smileys in.  |
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Suzaku
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« Reply #7 on: April 20, 2007, 09:39:21 am » |
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New smileys? AWESOME! :woot!:
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DarknessSavior
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« Reply #8 on: April 20, 2007, 09:43:48 am » |
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Ditto. :thumbsup:
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KaioShin
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« Reply #9 on: April 20, 2007, 10:08:52 am » |
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New smileys? AWESOME! :woot!:
Nooo, the old ones were better >_< |
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Gemini
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« Reply #10 on: April 20, 2007, 10:20:55 am » |
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I agree. Old smiles FTW. ;_;
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Tauwasser
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« Reply #11 on: April 20, 2007, 10:48:52 am » |
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No there is not. It just depends on how your mbc handles the data and everything. Usually, roms get padded so they are in the boundary of the next size limit (meaning, if you have...let's say 31 banks, you then have another one padded with FF or 00 or whatever).
0148 ROM size:
0 - 256Kbit = 32KByte = 2 banks
That might be the minimum (like for the chips and such), but... you can't really program anything a lot smaller than that anyways... That's two banks... It's nothing when you want to have some gfx in there too...
EDIT: Oh yeah, cut the smiley crap. Use the appropriate topic.
cYa,
Tauwasser
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