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PowerMappers (a new set of PowerPak mappers)
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Author:  thefox [ Wed Oct 22, 2014 7:43 am ]
Post subject:  PowerMappers (a new set of PowerPak mappers)

PowerMappers is a new set of mappers for the PowerPak NES flash cartridge. It is a complete rewrite of my previous Save State Mappers. I have been sitting on this for a while, but since there hasn't been significant progress in the last month or so, this seems like a good time to release it.

Download at https://kkfos.aspekt.fi/

If you encounter any problems, let me know. This is still in a beta state.

(Cross-posted to NintendoAGE forums.)

Author:  ccovell [ Wed Oct 22, 2014 6:01 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Thanks for the hard work! I'll try them out.

Author:  koitsu [ Wed Oct 22, 2014 6:32 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Do these contain whatever fixes were in loopy's mapper set for MMC3? (It's been a while...) I can pull my PowerPak out and test stuff if you need it!

Author:  thefox [ Thu Oct 23, 2014 4:06 am ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

koitsu wrote:
Do these contain whatever fixes were in loopy's mapper set for MMC3? (It's been a while...) I can pull my PowerPak out and test stuff if you need it!

MMC3 IRQ should be the same as in loopy's mappers. However, it can still be problematic for a couple of different reasons. It works well enough on my setup.

I don't have anything specific for you to test, but general testing would be welcome, since this was only tested by myself before release, and also very briefly by Pasky.

There was issue on one of Pasky's AV Famicoms (I believe) where loading would corrupt the nametable (in all mappers). Haven't been able to figure the cause of that one out yet, since I can't reproduce it.

Author:  JRoatch [ Fri Oct 24, 2014 8:05 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

So I go around to trying these out and to my surprise an particular NROM image that used to not work suddenly did. I guess I had *really* outdated mappers. Thank you. Also, nice touch on clearing the ram. :)

Author:  Great Hierophant [ Sun Oct 26, 2014 3:03 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Great work fox! Some comments on your compatibility list :

All the games that rely on bus capacitance for input work fine for me, but I didn't test save states.

Bubble Bath Babes, Hot Slots and Peek-A-Boo Poker all run with your new mappers.

Pin Bot, High Speed, Gauntlet and Rad Racer II and Conflict now run with the new mappers.

In your prior mapper 4, Bucky O'Hare's scanlines seemed to be solid.

For Startropics, Mike's sprite doesn't flicker for me, but the last scanline before the border does. I didn't notice any flickering sprites or scanlines in Startropics II.

Try as I might, I can't see anything wrong with Perfect Fit's graphics, but I can see issues with the other games you listed as corrupting CHR-ROM.

Mickey in Numberland has severe glitches and is not playable, but Letterland is playable.

Author:  thefox [ Sun Oct 26, 2014 3:54 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Great Hierophant wrote:
All the games that rely on bus capacitance for input work fine for me, but I didn't test save states.

Yeah, this is expected. I don't know what is wrong with this NES of mine that it has one of the controller bits high that's not supposed to be high.

Quote:
In your prior mapper 4, Bucky O'Hare's scanlines seemed to be solid.

Quote:
Mickey in Numberland has severe glitches and is not playable, but Letterland is playable.

MMC3 is really annoying to implement, because of the unclean PPU A12 that PowerPak provides. It's literally up to luck whether a certain revision of the mappers will work well or not, depending on how the logic is laid out. I'd suggest doing what the original MMC3 boards did, and add a 220 pf capacitor from ground to PPU A12 on the PowerPak. I'd be interested in hearing if this fixes any problems for anybody willing to try it.

Quote:
Try as I might, I can't see anything wrong with Perfect Fit's graphics, but I can see issues with the other games you listed as corrupting CHR-ROM.

IIRC you have to press SELECT to exit the game for the corruption to occur, or something like that. The CHR corruption problem is another flaw in the PowerPak hardware design and I don't know of a workaround for it (besides patching the ROM).

Author:  Great Hierophant [ Sun Oct 26, 2014 4:16 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

More MMC3 fun :

Crystalis - The screen shakes when a dialog window is present.

Star Trek 25th Anniversary - Corrupt graphics flicker when the dialog window appears on the ship. I see this with Little Ninja Bros. as well.

Author:  Great Hierophant [ Sun Oct 26, 2014 4:41 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Quote:
MMC3 is really annoying to implement, because of the unclean PPU A12 that PowerPak provides. It's literally up to luck whether a certain revision of the mappers will work well or not, depending on how the logic is laid out. I'd suggest doing what the original MMC3 boards did, and add a 220 pf capacitor from ground to PPU A12 on the PowerPak. I'd be interested in hearing if this fixes any problems for anybody willing to try it.


Is this as simple as putting one leg of a capacitor on PPU/CHR A12 (say at pin 64 of the cartridge connector) and another leg on GND? Would this have any negative effect on games that do not use MMC3? Sounds easy enough to try.

Author:  thefox [ Sun Oct 26, 2014 7:47 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

Great Hierophant wrote:
Is this as simple as putting one leg of a capacitor on PPU/CHR A12 (say at pin 64 of the cartridge connector) and another leg on GND? Would this have any negative effect on games that do not use MMC3? Sounds easy enough to try.

As far as I understand, the cap should preferably be placed as close to the FPGA input as possible, but I'm no electrical engineer. Placing it close might be hard, though, so you can try placing it at the cart connector I guess. It shouldn't have any negative effects on other mappers/games.

Author:  2600 [ Mon Oct 27, 2014 11:28 am ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

A digital delay filter within your mapper might work as well.

Author:  thefox [ Mon Oct 27, 2014 11:46 am ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

2600 wrote:
A digital delay filter within your mapper might work as well.

Such implementation couldn't match the real MMC3 behavior very closely though, because on a real MMC3 the IRQ is asserted directly on the rising edge of A12.

Author:  2600 [ Mon Oct 27, 2014 12:16 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

thefox wrote:
2600 wrote:
A digital delay filter within your mapper might work as well.

Such implementation couldn't match the real MMC3 behavior very closely though, because on a real MMC3 the IRQ is asserted directly on the rising edge of A12.


I think it could match it closely, but you may think differently. I'm just talking about a delay of a few ns. Enough to filter out the random spike. The capacitor delays the rising edge of A12 as seen by the MMC3 as well.

Author:  thefox [ Mon Oct 27, 2014 12:18 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

2600 wrote:
I think it could match it closely, but you may think differently. I'm just talking about a delay of a few ns. Enough to filter out the random spike. The capacitor delays the rising edge of A12 as seen by the MMC3 as well.

How do you implement a few ns delay digitally? The PowerPak's on-board clock is 20 MHz.

Author:  2600 [ Mon Oct 27, 2014 12:26 pm ]
Post subject:  Re: PowerMappers (a new set of PowerPak mappers)

You have A12 go through a buffer or two and let's call this A12_delay. Then you AND A12_delay with A12. You'll need to make sure that ISE doesn't optimize out the buffer so you may want to use 2 NOT gates, AND gates, or whatever instead of a buffer.

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