Which one has a longer life?

socram8888 · Post by **socram8888** » Sat Apr 23, 2011 1:56 am

I want to do a Gimmick! reproduction. I want to use the longest-life memory devices (because of couse I don't want a useless cartridge after just some years), but I don't know which one loses bits first: EPROM or FLASH

I searched for PROMs (which uses fuses) but no luck

3gengames · Post by **3gengames** » Sat Apr 23, 2011 2:28 am

Flash would be better for your needs I think.

Post by **Memblers** » Sat Apr 23, 2011 2:48 am

I believe EPROM and Flash are really similar, actually (the underlying technology). But I did notice and just checked, the SST39SF series Flash claims "greater than 100 years data retention". AMD Flashroms claim 20 years at 125 degrees C (that's 250+ Fahrenheit), I'm sure it would last quite a while at room temperature.

socram8888 · Post by **socram8888** » Sat Apr 23, 2011 3:50 am

Thanks

Then which memory chips should I use? 28Fxxx, 29Fxxx, 39Fxxx, ...?

In my MMC3 devcart I'm using two Am28F020 from 1991, but I prefer to use newer chips this time

FARID · Post by **FARID** » Sat Apr 23, 2011 9:25 am

So what is the advantage of EPROM over Flash? Even I had bought AM29F010 and AT27C010 the same price! I would have thought EPROM has more life but it is one time programmable, and Flash has less life but it can be programmed several times.

3gengames · Post by **3gengames** » Sat Apr 23, 2011 9:28 am

What? Flash is better [to me] because with EPROMS, UV rays will always get into it and decay it over time no matter what. Flash doesn't have that problem. Flash is also faster to program and reprogram.

socram8888 · Post by **socram8888** » Sat Apr 23, 2011 10:23 am

FARID wrote:So what is the advantage of EPROM over Flash? Even I had bought AM29F010 and AT27C010 the same price! I would have thought EPROM has more life but it is one time programmable, and Flash has less life but it can be programmed several times.

EPROM was used when Flash doesn't even existed. That's why

MottZilla · Post by **MottZilla** » Sat Apr 23, 2011 2:05 pm

EPROMs still last a long time. They can be reprogrammed. It involves recharging the memory bit cells by exposure to a certain frequency of UV light. OTP EPROMs don't have the quartz window and thus are one time programmable hence OTP.

Flash as far as we know is pretty stable and in theory more stable than EPROMs. MaskROMs are even more stable than both, at least in theory.

I too would use Flash over EPROM for something intended to last a long time, but keep in mind tons of Arcade Games stored game data on EPROMs and are very old now and still work fine and have not suffered bit rot. If you properly erase and program EPROMs your data will last for many years, 20 years and maybe more. It's hard to say. Though I guess since more factors are at work compared to Flash you might want to go with that for more consistent results.

socram8888 · Post by **socram8888** » Sat Apr 23, 2011 2:28 pm

OFC I can reprogram them, but that's exactly what I want to avoid (I don't think the PCB would last desoldering a chip a big DIP chip twice)

FARID · Post by **FARID** » Sat Apr 23, 2011 9:30 pm

socram8888 wrote:OFC I can reprogram them, but that's exactly what I want to avoid (I don't think the PCB would last desoldering a chip a big DIP chip twice)

I'd rather not solder chip directly to the PCB, instead I will use these legs :

3gengames · Post by **3gengames** » Sat Apr 23, 2011 9:34 pm

That's what I did to my NROM carts right above.

socram8888 · Post by **socram8888** » Sun Apr 24, 2011 1:24 am

FARID wrote:
socram8888 wrote:OFC I can reprogram them, but that's exactly what I want to avoid (I don't think the PCB would last desoldering a chip a big DIP chip twice)
I'd rather not solder chip directly to the PCB, instead I will use these legs :

I use these on my devcarts. But then I'll have to open a window, and I don't want a reproduction with a big hole on it

Well, which Flash series should I use?

TmEE · Post by **TmEE** » Sun Apr 24, 2011 5:04 am

Flash is way to go, they're usually cheaper and easier to find, at least for me. Pinouts are same aswell, and you can easily reprogram one if something goes whack.
As for what to use, get whatever your programmer uses. I prefer 5V only flash chips, which seem to be mostly 49F, though its not a rule. Just check datasheets before buying.

Post by **Memblers** » Sun Apr 24, 2011 4:10 pm

socram8888 wrote: Well, which Flash series should I use?

The only way we can investigate is to view the datasheets for any particular chip that's available to you. SST39SF is available from Digikey, at least. I have some AM29F040Bs, but I guess the shipping would cost more than the parts.