Suicide battery permanent fix with F-RAM?

Yrouel · Mar 28, 2016

Hello since I have a game with a suicide battery (World Rally by Gaelco) which is fortunately recoverable (kudos to Gaelco for officially releasing the binary file) I was looking at a more permanent fix.
Modern technology has now made available F-RAMs which are basically non volatile SRAMs equivalents.
So has anyone explored this possibility to fix this kind of issue (not necessarily for this particular game)?
In my specific case this is the original SRAM UPD43256AGU-85LL and this is the replacement I'm looking at 877-FM1808B-SG

leonk · Apr 2, 2016

I was under the impression that the non-volatile ram is just regular sram with a supercap to keep it alive. So you need to periodically hook it up and use it or supercap will drain and die. Also. Most important thing is to match electrical characteristics. Voltage. Pinout. Speed of chip.

shadowkn55 · Apr 2, 2016

The issue with using fram is that is has finite read/write endurance. Even though it's a very large number (100 trillion in the OPs case), it can quickly be used up if the original sram was used as a scratch pad like system ram. If the sole purpose of the sram was to store a key or settings that are seldom accessed, fram would be a good substitute. The Neo Geo memory card is a good example of it.

Apocalypse · Apr 6, 2016

Yrouel said:
Hello since I have a game with a suicide battery (World Rally by Gaelco) which is fortunately recoverable (kudos to Gaelco for officially releasing the binary file) I was looking at a more permanent fix.
Modern technology has now made available F-RAMs which are basically non volatile SRAMs equivalents.
So has anyone explored this possibility to fix this kind of issue (not necessarily for this particular game)?
In my specific case this is the original SRAM UPD43256AGU-85LL and this is the replacement I'm looking at 877-FM1808B-SG

Same game same problem...
I might give it a look (next week?).

leonk said:
I was under the impression that the non-volatile ram is just regular sram with a supercap to keep it alive. So you need to periodically hook it up and use it or supercap will drain and die. Also. Most important thing is to match electrical characteristics. Voltage. Pinout. Speed of chip.

Data are kept for a minimum of 151 years without any power. If you make the analogy with other products (CD-R/CR-RW, backup batteries) you can expect them to last far more. No worries at all.

shadowkn55 said:
The issue with using fram is that is has finite read/write endurance. Even though it's a very large number (100 trillion in the OPs case), it can quickly be used up if the original sram was used as a scratch pad like system ram. If the sole purpose of the sram was to store a key or settings that are seldom accessed, fram would be a good substitute. The Neo Geo memory card is a good example of it.

It should last a while (and as you mentioned, especially if used to store a key).

Suicide battery permanent fix with F-RAM?

Yrouel

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leonk

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shadowkn55

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Apocalypse

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