reversing mapper268: coolboy/mindkids

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Ben Boldt
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Re: reversing mapper268: coolboy/mindkids

Post by Ben Boldt » Wed Jan 08, 2020 7:41 pm

aquasnake wrote:
Wed Jan 08, 2020 9:17 am
i have 512KB PRG-RAM in my cart
Okay, so you hooked the highest address bits of the PRG-ROM up to the extra address bits of the RAM? Do you have a cheap source of 512kByte SRAMs? I have a cart just like that with the same problem.

aquasnake
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Re: reversing mapper268: coolboy/mindkids

Post by aquasnake » Sun Jan 12, 2020 10:51 pm

Ben Boldt wrote:
Wed Jan 08, 2020 7:41 pm
aquasnake wrote:
Wed Jan 08, 2020 9:17 am
i have 512KB PRG-RAM in my cart
Okay, so you hooked the highest address bits of the PRG-ROM up to the extra address bits of the RAM? Do you have a cheap source of 512kByte SRAMs? I have a cart just like that with the same problem.
due to the limitation of original mindkids' hardware, you must use aditional logic devices to generate either high bits of sram's address, or the mask bits of prg base address, and also spy sram-ce to bank these address dynamically, not just conncet the high bits of prg address to sram directly.

it's a bit complicated

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Ben Boldt
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Re: reversing mapper268: coolboy/mindkids

Post by Ben Boldt » Mon Jan 13, 2020 7:04 am

How many games actually can save in the cart? Is it possible to use a smaller SRAM, and then still share 1 chunk of the SRAM for the games that don't save? There are millions of these carts around that all have this problem, it would be cool to simplify things and provide rework instructions for people. Using the address bits more or less directly might be possible with modification to the cart's ROM / order of the games, etc.

Do you mind sharing the details how you did it? What considerations have you made concerning 3.3V logic in this cart? Are you powering the SRAM from 5V, 4.2V, or 3.3V? You said that you cloned the hardware -- does this mean that you are using all 5V logic, or properly level-shifted now?

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0Zeromus0
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Re: reversing mapper268: coolboy/mindkids

Post by 0Zeromus0 » Thu Mar 26, 2020 8:02 am

Ben Boldt wrote:
Mon Jan 13, 2020 7:04 am
How many games actually can save in the cart? Is it possible to use a smaller SRAM, and then still share 1 chunk of the SRAM for the games that don't save? There are millions of these carts around that all have this problem, it would be cool to simplify things and provide rework instructions for people. Using the address bits more or less directly might be possible with modification to the cart's ROM / order of the games, etc.

Do you mind sharing the details how you did it? What considerations have you made concerning 3.3V logic in this cart? Are you powering the SRAM from 5V, 4.2V, or 3.3V? You said that you cloned the hardware -- does this mean that you are using all 5V logic, or properly level-shifted now?
seems 20 games have save functions. no.9 26 27 38 41 42 43 63 71 82 89 103 105 114 115 120 121 135 140 141

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