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GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Mon Jan 23, 2023 3:15 pm
by hidden0
So just recently did SA1 with the help of so many people able to figure out things just wanted to ask if this topic has been covered cuz i found ziggy’s posts on another forum for gsu2 and did the upgrade was quite simple but cant find pinout or info regarding gsu1

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Mon Jan 23, 2023 9:53 pm
by hidden0
So the pinout i found does match with The stuntrace FX pcb with 512kb of ram 1CA0N6s but does not match with Starfox board 1CON5S with 256kb.
E.g Pin 79 of GSU-1 chip goes to A0 sram
But Pin 79 of Mario Chip is going to A1 of Sram

Similarly all the pins are slightly off what should i do.
I was thinking if using the 1Mb chip i had put in gsu 2 and SA1 boards in starfox mario chip 1 even though i just need 512kb out of that to make starfox 2 on starfox 1 board since i have many copies.

I dunno why it is like that or if that even matters.
All i can think of is install the 1Mb chip in 1CA05s board with pin 1/2/31/32 hanging put connect 1/2 to the ground Pin 31 A15 to Pin97 of Mario Chip and pin 32 to VCC and it should give me 512KB i believe.

Or is that wrong ?

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Tue Jan 24, 2023 1:50 am
by hidden0
Apparently mario chip has complete different pinout then the usual gsu-1 chip

I installed this sram connected the a15 to sram pin 97 as it was in the stunt race cartridge starfox worked fine but when i switch the maskrom to stunt race it is not booting .

Also starfox board lacks the X1

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Sat Feb 04, 2023 8:44 am
by hidden0
If anyone can shed light on the topic it will be really helpful.

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Mon Feb 06, 2023 3:55 pm
by Limewater
I don't have any great insight but...

I believe that Stunt Race FX uses a battery backup. I don't see a battery on your PCB. This is a more complicated situation than your previous one, where I don't think you were loading games that used battery saves.

Are you sure Stunt Race FX will run on that board?

You might try a rom with just Stunt Race FX, or one with Stunt Race FX in first position to see if it even runs apart from your dual-load plans.

Also, according to the Wikipedia article on SNES enhancement chips, the MARIO chip on your board has an internal clock divide and only runs at half the frequency of the GSU-1 chip that Stunt Race FX uses. This could also be a source of problems.

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Fri Feb 10, 2023 12:34 am
by hidden0
Limewater wrote:I don't have any great insight but...

I believe that Stunt Race FX uses a battery backup. I don't see a battery on your PCB. This is a more complicated situation than your previous one, where I don't think you were loading games that used battery saves.

Are you sure Stunt Race FX will run on that board?

You might try a rom with just Stunt Race FX, or one with Stunt Race FX in first position to see if it even runs apart from your dual-load plans.

Also, according to the Wikipedia article on SNES enhancement chips, the MARIO chip on your board has an internal clock divide and only runs at half the frequency of the GSU-1 chip that Stunt Race FX uses. This could also be a source of problems.


The only thing i know Stuntrace does work on Dirt FX board which has no battery backup , it just does'nt save, Same goes with with Starfox 2 , Can use both Dirt FX boards no battery and stuntrace fx with battery ,

It is just wiring thats the issue i am sure @Ziggy587 can shed some light on it.

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Fri Feb 10, 2023 12:51 pm
by Limewater
But Dirt Trax FX uses the GSU-1, the same as Stunt Race FX, which runs at twice the clock speed of the MARIO chip you're showing on your PCBs.

The GSU-1 and MARIO have the same external clock, but the MARIO clock has an internal divide-by-2.

It is possible that Stunt Race FX won't run on that board regardless of whether you get your SRAM wired correctly. There may be a timing check in the boot sequence that it is failing. And even if it does run, it most likely won't run well.

It sounds like your end goal is to try to make a Starfox 2 cart, but you will run into the same issue with the GSU-2 game most likely not running on a MARIO.

Re: GSU-1 Sram Upgrade on from 256k to 1Mb

Posted: Tue Feb 14, 2023 5:12 am
by hidden0
Limewater wrote:But Dirt Trax FX uses the GSU-1, the same as Stunt Race FX, which runs at twice the clock speed of the MARIO chip you're showing on your PCBs.

The GSU-1 and MARIO have the same external clock, but the MARIO clock has an internal divide-by-2.

It is possible that Stunt Race FX won't run on that board regardless of whether you get your SRAM wired correctly. There may be a timing check in the boot sequence that it is failing. And even if it does run, it most likely won't run well.

It sounds like your end goal is to try to make a Starfox 2 cart, but you will run into the same issue with the GSU-2 game most likely not running on a MARIO.


GSU 1 - Mario Chip suppose to be the same , CUZ stunt race Cartridge with GSU-1 Plays Starfox just fine . SO it should plays Starfox 2 , The issue is sram.