Putting 256Kbit sram into a 64Kbit cart

Putting 256Kbit sram into a 64Kbit cart
by getafixx on 2014-02-13 (#125487)

I apologize if this has been posted before...I did a search and couldn't find what I was looking for.

I was trying to make myself a Fire Emblem Thracia 776 cart (which uses a 256Kbit sram), using a NBA live '96 cart (64kbit sram,has the Mad-1 chip). What I did is take a 256kbit sram and dropped it in place of the 64Kbit sram that had been in there, lifted the legs up on A13 and A14 and jumpered those manually to rom A13-14. Now, the game boots and plays properly on my FCTwin but it won't save ...and it crashes after selecting a new game on my SNES 1 and jr.

I have tested it on my Powerpak, and it works properly on there. So, is there something else that has to be done to get the larger SRAM to work on a standard 64k cart aside from jumping the extra 2 address lines?

Re: Putting 256Kbit sram into a 64Kbit cart
by nintendo2600 on 2014-02-19 (#125767)

To add a second request to anyone reading, myself I was wondering
about a schematic for replacing a 16k SRAM with a 64k SRAM. I have
some NBA TE carts that would be alot more useful if I could add more
ram to them.

Re: Putting 256Kbit sram into a 64Kbit cart
by Markfrizb on 2014-06-20 (#130038)

getafixx wrote:

I apologize if this has been posted before...I did a search and couldn't find what I was looking for.

I was trying to make myself a Fire Emblem Thracia 776 cart (which uses a 256Kbit sram), using a NBA live '96 cart (64kbit sram,has the Mad-1 chip). What I did is take a 256kbit sram and dropped it in place of the 64Kbit sram that had been in there, lifted the legs up on A13 and A14 and jumpered those manually to rom A13-14. Now, the game boots and plays properly on my FCTwin but it won't save ...and it crashes after selecting a new game on my SNES 1 and jr.

I have tested it on my Powerpak, and it works properly on there. So, is there something else that has to be done to get the larger SRAM to work on a standard 64k cart aside from jumping the extra 2 address lines?

Did you ever solve this issue?

Re: Putting 256Kbit sram into a 64Kbit cart
by Tormenter on 2014-06-24 (#130206)

Markfrizb wrote:

getafixx wrote:

I apologize if this has been posted before...I did a search and couldn't find what I was looking for.

I was trying to make myself a Fire Emblem Thracia 776 cart (which uses a 256Kbit sram), using a NBA live '96 cart (64kbit sram,has the Mad-1 chip). What I did is take a 256kbit sram and dropped it in place of the 64Kbit sram that had been in there, lifted the legs up on A13 and A14 and jumpered those manually to rom A13-14. Now, the game boots and plays properly on my FCTwin but it won't save ...and it crashes after selecting a new game on my SNES 1 and jr.

I have tested it on my Powerpak, and it works properly on there. So, is there something else that has to be done to get the larger SRAM to work on a standard 64k cart aside from jumping the extra 2 address lines?

Did you ever solve this issue?

Yeah I would kinda like to know as well heheh

Re: Putting 256Kbit sram into a 64Kbit cart
by Markfrizb on 2014-06-24 (#130208)

getafixx wrote:

I apologize if this has been posted before...I did a search and couldn't find what I was looking for.

I was trying to make myself a Fire Emblem Thracia 776 cart (which uses a 256Kbit sram), using a NBA live '96 cart (64kbit sram,has the Mad-1 chip). What I did is take a 256kbit sram and dropped it in place of the 64Kbit sram that had been in there, lifted the legs up on A13 and A14 and jumpered those manually to rom A13-14. Now, the game boots and plays properly on my FCTwin but it won't save ...and it crashes after selecting a new game on my SNES 1 and jr.

I have tested it on my Powerpak, and it works properly on there. So, is there something else that has to be done to get the larger SRAM to work on a standard 64k cart aside from jumping the extra 2 address lines?

I'm wondering if you need a small pull up resistor on A13,14