Cartridge ROM mapping

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kevgal
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Re: Cartridge ROM mapping

Post by kevgal » Sun Mar 26, 2023 7:18 am

Finally got all the roms behaving as 32k roms but I can't figure out how to get the 18k Chopper game to work as a 32k rom. Tried various combinations of banks but to no avail.
Any Ideas?
(My multi cart wasn't wired correctly either its now A13 goes to A13 and /ROM2 goes to A14)
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MADrigal
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Re: Cartridge ROM mapping

Post by MADrigal » Sun Mar 26, 2023 7:41 am

There must be a memory map diagram I made, somewhere here on the forum, showing all combinations of eproms
For 18k, the end 2k go on the low rom bank ($4000) possibly mirrored 8 times (it won't harm doing it) and the first 16k on the high rom bank ($8000). Not sure if the 16k must be split and swapped, or the go plain as they are. Please try both. Bit if you can find that diagram here on the forum, happy days
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@username@
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Re: Cartridge ROM mapping

Post by @username@ » Sun Mar 26, 2023 8:14 am

kevgal wrote:
Sun Mar 26, 2023 7:18 am
Finally got all the roms behaving as 32k roms but I can't figure out how to get the 18k Chopper game to work as a 32k rom. Tried various combinations of banks but to no avail.
Is this your preferred way to get your lottery numbers :D

An 18K ROM, if downloaded from here, it will be stored in this format.

4K -> $A000
4K -> $B000 --- This is the really important one - there is no ISR, ROM, NMI etc if this is not here
4K -> $8000
4K -> $9000
2K -> $7000

MAME has now started doing ROMs by ID- so maybe that would be a better place to start if memory addressing is confusing.
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Scouter3d
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Re: Cartridge ROM mapping

Post by Scouter3d » Sun Mar 26, 2023 8:33 am

Hi, here is the cartridge-memory-map @MADrigal is reffering to two posts before...
Cheers, TOM:0)
Memory%20map%20new.gif
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MADrigal
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Re: Cartridge ROM mapping

Post by MADrigal » Sun Mar 26, 2023 8:38 am

Thanks Tom! That's the one
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@username@
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Re: Cartridge ROM mapping

Post by @username@ » Sun Mar 26, 2023 9:04 am

Ok guys - please point me to any ROM which has mirroring at $B800 - it's nonsense!

4K + 2K is inverted - 4K block is at $B000, 2K page is at either $A000 or $A800, or mirrored to both.
kevgal
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Re: Cartridge ROM mapping

Post by kevgal » Sun Mar 26, 2023 11:47 am

Well that looks quite straight forward :?
Her's what I did to make 32k roms that work in the emulator and the real thing (not always the case!)
Cheers,
Kev
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MADrigal
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Re: Cartridge ROM mapping

Post by MADrigal » Sun Mar 26, 2023 1:15 pm

@username@ wrote:
Sun Mar 26, 2023 9:04 am
Ok guys - please point me to any ROM which has mirroring at $B800 - it's nonsense!

4K + 2K is inverted - 4K block is at $B000, 2K page is at either $A000 or $A800, or mirrored to both.
The mirroring is done via hardware in the cartridge. That's all.
Whether the actual program uses any mirrored rom banks is another story. But if you wish to replicate the actual hardware of the cartridge, your replica/emulation wouldn't be accurate if mirroring wasn't there.
From memory there's one version of Basic that makes use of one mirrored bank.
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@username@
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Re: Cartridge ROM mapping

Post by @username@ » Sun Mar 26, 2023 2:21 pm

Sorry - I call bullshit on that one.

Please look at your chart again and explain why only the 6K ROM has the wrong memory addresses swapped.

Tell me the name of the 6K ROM you think can be cut up this way and still work.
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MADrigal
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Re: Cartridge ROM mapping

Post by MADrigal » Sun Mar 26, 2023 2:35 pm

The diagram for the 6k may be incorrect but the principle is that mirroring is done at hardware level by the various configurations of the cartridges
I don't own the Tank Attack cartridges anymore so I have really no way to either confirm or not whether the diagram is correct, how I got to it or else.
To sum up: the 6k diagram may be incorrect and, the logic comes from the specific cartridges. I don't think this is enough to start a heated argument although I understand that one can be more passionate than others about tit.
Also note that diagram was done around 2007, that's long ago and based on study or cartridge diagrams I had at the time. You are.welcome to edit, change, scrap or update it to a better versione for everyones use. thanks
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