So I'm down to my last few famicom carts dump (out of this batch anyways ), which are Namco 106 carts. I saved them for last because they use registers at $4800-4FFF which also happens to be in the same address space that CopyNES uses for it's port chip :/ So they crash the NES 99.9% of the time. Luckily Kevtris had the foresight to allow changing the BIOS to use $4000-47FF instead. Well I tried changing the BIOS itself to default to that mode, but I had no luck with that. So instead I ended up modifying a famicom adapter and adding resistors to the PRG data lines to allow me to win the bus and change the mode via the plugin. So now they work most of the time.
So that's one hurdle overcome, but now I've run into somethings I can't quite figure out, nothing that prevents me from dumping, but still important. Every 106 cart I have uses those damn epoxy glob pcbs, so that doesn't help matters either. Anyways, on to the questions.
1) Apparently the 106 contains some VRAM on chip, anyone know how much?
2) I have a number of these carts that have batteries but don't appear to have any WRAM at all!? Is it possible they are saving game data to this internal VRAM instead of using it for video purposes?
3) One cart does appear to have WRAM (again, globtops, so not sure, but based on location on board I think it is) but it's either not mapped to $6000-7fff or something special needs to be done to enable it. I stepped thru some of the code (the game in question is Dokuganryuu Masamune) and I see some writing to $6000 only, but it seems more like it's being used as a register for something and the values it writes don't show up in that memory area. I haven't seen any docs mention anything about these carts and WRAM, or using $6000 as a register.
If I try to read this area with CopyNES, I just get open bus, same goes for the games with batteries but no apparent WRAM present.
A few of these are in the DB, take a look at Kaijuu Monogatari which has a battery but no WRAM (looks like there is a spot for it though) and Dokuganryuu Masamune which I'm guessing the blob on the leftmost side is WRAM.
Any insight on these matters would be much appreciated!
On a side note, as I've been dumping these famicom carts, I've been finding lots of errors in current docs about how some mappers work, wrong mapper assignments, etc. I've even been finding that a number of current dumps of games have been "mapper-hacked" to work with a different mapper. I'm planning on posting about all this soon, so emu authors, keep your eyes peeled
So that's one hurdle overcome, but now I've run into somethings I can't quite figure out, nothing that prevents me from dumping, but still important. Every 106 cart I have uses those damn epoxy glob pcbs, so that doesn't help matters either. Anyways, on to the questions.
1) Apparently the 106 contains some VRAM on chip, anyone know how much?
2) I have a number of these carts that have batteries but don't appear to have any WRAM at all!? Is it possible they are saving game data to this internal VRAM instead of using it for video purposes?
3) One cart does appear to have WRAM (again, globtops, so not sure, but based on location on board I think it is) but it's either not mapped to $6000-7fff or something special needs to be done to enable it. I stepped thru some of the code (the game in question is Dokuganryuu Masamune) and I see some writing to $6000 only, but it seems more like it's being used as a register for something and the values it writes don't show up in that memory area. I haven't seen any docs mention anything about these carts and WRAM, or using $6000 as a register.
If I try to read this area with CopyNES, I just get open bus, same goes for the games with batteries but no apparent WRAM present.
A few of these are in the DB, take a look at Kaijuu Monogatari which has a battery but no WRAM (looks like there is a spot for it though) and Dokuganryuu Masamune which I'm guessing the blob on the leftmost side is WRAM.
Any insight on these matters would be much appreciated!
On a side note, as I've been dumping these famicom carts, I've been finding lots of errors in current docs about how some mappers work, wrong mapper assignments, etc. I've even been finding that a number of current dumps of games have been "mapper-hacked" to work with a different mapper. I'm planning on posting about all this soon, so emu authors, keep your eyes peeled