catskull
Offline
NUMBSKULL

Today I wanted to be able to completely erase my EMS 64m USB cart. Using nitro2k01's multi rom menu, sometime's "old" roms would show up in the menu that I didn't want there any more.

I wrote up the process on my blog: http://catskull.net/gameboy/hack/2015/0 … eboy-cart/

Please let me know if I've made any huge mistakes here.

Jazzmarazz
Offline
Michigan

I suggest filling it with 1's rather than 0's. This is because when writing to an erased ROM, the device can only transition from 1 to 0 and not from 0 to 1 without going through the erase sequence. That is to say that all 1's is technically "empty" and all 0's is technically "full."

I am just being picky of course. This is a fine idea for a guide.

egr
Offline
Abandoned on Fire

Nitro's lsdj file manager is called LittleFM, LSMC is a recent sav management program for PC.

Nicely done article tho!

Last edited by egr (Apr 15, 2015 4:55 am)

catskull
Offline
NUMBSKULL
Jazzmarazz wrote:

I suggest filling it with 1's rather than 0's. This is because when writing to an erased ROM, the device can only transition from 1 to 0 and not from 0 to 1 without going through the erase sequence. That is to say that all 1's is technically "empty" and all 0's is technically "full."

I am just being picky of course. This is a fine idea for a guide.

Ah, good to know. That would be referred to as low-asserted logic correct? Is that normal behavior for most roms?

egr wrote:

Nitro's lsdj file manager is called LittleFM, LSMC is a recent sav management program for PC.

Nicely done article tho!

Thanks for that. I get confused with all the LS-whatever's floating around by now.

nitro2k01
Offline
Sweeeeeeden

So the short story is that the cart itself is “dumb”, and their patched multirom menu could be used just as well on almost any flash cart.

This is completely false. To be able to do multi-ROM, the cartridge needs to be able to remap the ROM space so the select ROM thinks it's the only ROM on the cartridge. This requires that the cartridge has this capability. You still need a program of some kind that can look for multiple ROMs and poke the cartridge the right way to be able to run one of the other ROMs..

catskull
Offline
NUMBSKULL

Well I clearly have no idea what I'm talking about here. Just taking shots in the dark. If you write a more detailed explanation of how their multi ROM works (and how you were able to do it in littleFM) I'd love to read it and link to it from my blog post. Until then, I'll just retract that statement.

Thanks for pointing that out!

Maybe I should have a disclaimer at the top that says I really have no idea what I'm talking about?

BennVenn
Offline
Australia

You were on the right track Catskull, the menu itself is compiled into the ROM and without it, the cart becomes a 'dumb' standard cartridge but as Nitro said, the ROM mapping/swapping is all done in hardware and most flash carts use their own unique method of selecting ROM's. I believe Nitro has documented the magic in one of his blogs.

nitro2k01
Offline
Sweeeeeeden

The protocol is documented, perhaps in excessive detail, here.

http://blog.gg8.se/wordpress/2013/03/04 … fects-you/

Or as a direct link to the text file with the gory details.
http://blog.gg8.se/gameboyprojects/week09/EMS_FAQ.txt

catskull
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NUMBSKULL

Thanks, updated the post to link to your documentation.