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PostPosted: Mon Jul 23, 2018 10:52 am 
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Most of the programmable logic options seem to blow the DMG's power budget.

But we could easily make reproductions of Wisdom Tree's GB discrete logic mapper.

Maybe I'll ever get around to actually designing and placing an order for parts for my "DMG mapper for self-flashing"


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PostPosted: Mon Jul 23, 2018 11:07 am 
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Wisdom Tree's GB mapper is the one that's like BNROM, correct?

Would a 2-chip mapper (74HC161 quad latch with binary counter + 74HC08 quad AND) implementing the same logic as UNROM (180) blow the power budget? (The '161 might need to be replaced with something different for clock and enable polarity.) At least it'd be mostly compatible with software designed for a standard MBC and no RAM.


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PostPosted: Mon Jul 23, 2018 11:26 am 
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Yes, Wisdom Tree's DMG mapper is basically BNROM.

You're right: as far as I can tell, a pure 74HC-based mapper should be fine, other than geometry constraints. With the caveat that using a single 74'08 restricts you to 256K of ROM. And that a 512K ROM can emulate the standard MBC memory map of a 256K ROM by modifying the image to be flashed.


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PostPosted: Mon Jul 23, 2018 11:39 am 
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lidnariq wrote:
as far as I can tell, a pure 74HC-based mapper should be fine, other than geometry constraints. With the caveat that using a single 74'08 restricts you to 256K of ROM.

True. For now, we'll cross that bridge when the scene as a whole gets to it. And right now, the scene has "got to" 64K, 128K, and 256K.


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PostPosted: Mon Jul 23, 2018 2:06 pm 
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rychan wrote:
It's a shame there's no real support for homebrew gameboy cartridges (to be sold) over the 32kb limit.

I'm currently waiting for an old 32kb gameboy color game I made a while ago to be put onto cartridge, although if I hear of anyone with MBC support I'll let you know if you're interested of course.


Thanks rychan, please keep me updated!

In the context of my earlier project "Retroid" I got hold of a PCB layout that works with ROMs up to 256kb. If you need that, feel free to drop me a PM or a message via the contact form on my website.


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PostPosted: Tue Jul 24, 2018 4:38 am 
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Ohhhh! Yeah, that would be interesting! I've no experience with making PCBs but I know someone local who does!


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PostPosted: Tue Jul 24, 2018 11:10 am 
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I made a topic in the GB section here listing all providers of boards. If you have new ones, can you post there?


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PostPosted: Sat Jul 28, 2018 9:23 am 
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I think it should be fixed so that the scores are not always a multiple of ten, by dividing the existing scores by ten, so that more points will fit on the display at once, because currently it is not enough.

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PostPosted: Sun Jul 29, 2018 5:43 am 
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zzo38 wrote:
I think it should be fixed so that the scores are not always a multiple of ten, by dividing the existing scores by ten, so that more points will fit on the display at once, because currently it is not enough.


Seriously? :P In endless hours of bug-testing, I managed to max out the score counter only once (and only in easy mode). In most cases I end up with a score that is way lower. I'd rather doubt that anybody can reach the maximum without a lot of practice.


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PostPosted: Mon Jul 30, 2018 1:00 am 
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I have my own cartridge design with 8 MiB of Flash, 128 KiB of SRAM (battery backed) and a working implementation of the MBC5 mapper. I have also a USB programmer designed to burn the cartridges. This should cover with ease all the needs of any homebrew GB/GBC game!


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PostPosted: Mon Jul 30, 2018 4:06 am 
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Jonas wrote:
Seriously? :P In endless hours of bug-testing, I managed to max out the score counter only once (and only in easy mode). In most cases I end up with a score that is way lower. I'd rather doubt that anybody can reach the maximum without a lot of practice.

You should always expect people to take your game to much a further extent than you can mange yourself! :) If they do that, it's only a sign of good game design.


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PostPosted: Mon Jul 30, 2018 12:59 pm 
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If anyone is curious, here is a render of the cartridge design, and a photograph of the programmer and a prototype assembled (excepting the SRAM and the battery circuit).

Image Image


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PostPosted: Mon Jul 30, 2018 9:47 pm 
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Lovely game. :D I played it for a good hour, and was getting the hang of the strategy I think.

This makes me want to try a bit of GB dev now too. Easily my favorite handheld ever, I still have mine next to my bed 25+ years later. I've just never found myself to find Z80 assembly fun though. :-\


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PostPosted: Tue Jul 31, 2018 4:32 am 
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Sumez wrote:
You should always expect people to take your game to much a further extent than you can mange yourself! :) If they do that, it's only a sign of good game design.


Thanks - and yes, I agree!

doragasu wrote:
If anyone is curious, here is a render of the cartridge design, and a photograph of the programmer and a prototype assembled (excepting the SRAM and the battery circuit).


I might be very interested some time in the future and will conatct you in that case. :) At the moment, I have a PCB design that has all I need but yours seems to have many additional features.

slembcke wrote:
Lovely game. :D I played it for a good hour, and was getting the hang of the strategy I think.

This makes me want to try a bit of GB dev now too. Easily my favorite handheld ever, I still have mine next to my bed 25+ years later. I've just never found myself to find Z80 assembly fun though. :-\


Thank you! :) I hope you try it some time. The community of Game Boy developers is very small, so every member counts.


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PostPosted: Thu Aug 16, 2018 5:55 pm 
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This game is good. I made a DOS version too: http://zzo38computer.org/GAMES/MEGAPANE.ZIP

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