Memory Mod - I screwed up

[nevercameback5000]

Hey guys,
Wanting to do the memory FRAM mod, I had an idea that I'd install TWO FRAM chips, and be able to switch between either via toggle switches on the side of the console. Essentially doubling the size of the memory. 

The first chip I installed this way worked. I was able to save games, etc.
The second chip did NOT work. The saturn would say the memory is "0" when going to clear it - same as it does if you have no chip installed at all. Shortly after I noticed there was a glob of solder bridging two pins on the 2nd chip (not pictured). I corrected the situation, however the chip was still not recognized.

FRAM chip #1 still worked however, until toggling back and forth a few times (with the power off). During troubleshooting, I noticed FRAM chip #1 had a few extra files "Saved" on it, two taking 1 space, and a third taking a few more blocks... I went to remove one, and ever since - The FRAM chip #1 is now too no longer recoginzed. I even went back and installed the old RAM chip - and even that is now no longer recognized by the Saturn. 
 
I'm under the impression that I royally screwed something up on the Saturn motherboard - since it is no longer recognizing any of the chips. 
Any hardware experts out there have any ideas?

[zyrobs]

It's not impossible you tore off a trace while soldering. Note, have you tried formatting the memory? Sometimes when something is broken, it's just junk data in the memory space and you need to format it to set up the defaults so the filesystem is recognized.

I'm not an electrician but soldering one line to every trace does not seem right to me - I think you could get away by having both chips connected at the same time and just switching between whichever pin activates the chip, like how some of those Dreamcast firmware mods work. But you'll need to consult with someone more experienced on how to set that up.

[nevercameback5000]

I didn't know you could format the memory - that is possible via the Saturn main menu? 
It kind of stopped working mid-testing it out, trying to get the second FRAM chip to be recognized. So it worked, no soldering / modding took place, then after switching back and forth, it stopped working. I'm thinking it had something to do with the order I toggled the switches (there are 8 of them, most have four traces on each one). 

I don't know what harm the wires can do aside from adding some resistance.

I probably have to accept that this Saturn is toast - I'd love it if someone bolder than me can attempt a similar mod - I'm sure there is room for improvement and better parts I don't even know about. As you said, toggling just the power instead of all 28 pins... that is a good idea.

I wonder if anyone knows the sequence that is initated on start-up to analyze the free memory... I've tried to check some of the pins.. I have 5VDC on WE, OE, and CD.. according to the chart below, when CE is high, the chip is disabled... I can't understand if it's supposed to be disabled most of the time, or what. The read write could happen at such speeds I would never be able to tell anything by checking each pin... I wish I knew more about electronics.

[zyrobs]

The Clear Memory option formats the device. Sometimes when you have a corrupt device that shows size as 0, this is the only thing that can restore it.

Yeah, I was thinking of the CE pin. The Dreamcast dual bios mods use that to switch from the original boot rom to the piggybacked flash one, which is soldered onto the pins of the original chip.

There's nothing wrong with soldering all wires to a switch, other than that you need to solder all wires to a switch, and the chance for screwing something up increases exponentially with each wire.

edit: also keep in mind that they stopped making those FRAM chips a long time ago, whatever stock exists today is either old stock or Chinese bootlegs.

[nevercameback5000]

I have a 10 pack of the Ramtrons coming. Plus two with long legs for sockets. I suppose they could be bootlegs.
I found this socket adapter which may serve my other idea; To have swappable FRAM chips under the lid of the saturn.
- SOP28 to DIP28 Socket Adapter

If I continue with the dual FRAM chip toggle switch idea, maybe I will try your idea - I will stack up two FRAM chips, and have the boards 5VDC power going to the common of a switch, with the other two legs connecting to each FRAM chip. Hopefully the inactive chip will have no effect on the active while receiving the same read and write data / requests. According to this, when the voltage is low on a chip, the chip is disabled - Not sure if that is the full story.

 


With all the retro mods available - I can't believe there is no solid memory expansion option for the Saturn, aside from carts that only support a handful of games, and the MODE which lets you back-up the entire memory bank (which I find inconvenient). The on board memory is comically small - you play two of the bigger games and the thing is full.

I bought a new motherboard for the broken Saturn, and have a second Saturn coming in... Will report a status update sometime this week.

[zyrobs]

I'd just use a normal backup cart. The action replay is not needed if you have a region free bios (except for cheats), PseudoSaturn was never really needed with modchips and ODEs, and the 4MB cart is only needed for a few titles. But because of the way the cart slot is mapped, you can't have an all-in-one cart, you either have a backup cart or an executable cart with memory expansion. One rules out the other. The only other option is having an on-cart switch to toggle each mode.

The MODE memory backup is useful for making a backup of all of your memory, to save it from being lost when you change battery or get a new cart and want to transfer the entire thing... it's more useful then you'd think.

[zyrobs]

Out of interest, where did you bought a spare motherboard for the broken Saturn? I need one as well.

I wouldn't swap around the 5VDC input, since if you stack the chips you will have the address pins connected and who knows what happens in the other chip without the VDC signal. I'd try using the Chip Enable pin first.

[nevercameback5000]

I looked one up in Google and found one on Etsy... A seller called FFFGamingEmporium seems to sell systems piece by piece. Sadly this was the only saturn motherboard he had (it's a model MK-80000A - Black, round button type). $45. Eventually more will show up somewhere.

Since I now have two Saturns, I tested what you mentioned before:




Sadly the results are less than ideal.
First I only divided out the 5 VDC power pin. However when I did this, both chips received the same saved states. It was essentially like having a back-up memory chip.

Then I wired it as per the picture above. This time, I saved Sonic Jam on one, and Nights on the other. It seemed to work, except when I switched back to the other memory chip, the game was there... When I switched back to the first memory chip, now this one says 0 memory. Clearing it works this time in "reformatting" the chip, but the save is lost. 

My next thing is to take all of the input wires and separate them out too. I may have to try my original plan of separating out all 28 pins with the switches. If I break this motherboard, I may have to finally give it up.

[nevercameback5000]

This time it seems to work.
It's not pretty, but I get double memory now. If someone would have some kind of ribbon cable and switch set-up they could improve this.



The harness was a bad idea - that is why I switched one out and landed wires directly on the chip.

One downside is if any of the 8 switches gets flipped while the system is on, I'm guessing the memory will get corrupted. I ruined one memory chip while doing this mod. It wasn't hard to do. One wire came off, and the memory chip was reading as like 800,000 blocks. Couldn't clear it, even after correcting the wiring. Then weird symbols were showing up. 

This mod took a lot of time - it would have been much easier to buy a mode. But I'm always looking for the next soldering project.

[nevercameback5000]

Thought I'd show one more of the complete thing.

[captainkael]

that is alot of switches!!!

[nevercameback5000]

Wanted to come back and say this turned out to be a disaster. For reasons not understood, the two memory chips worked good enough, switching back and forth - no problems. When I de-powered the system for a few days and came back, both chips are now corrupted. Can't clear and listed as 0 memory.

I thought it was because I had used PSKAI CD to load in a Shining Force 3 save. So I installed two new chips. Again things were good.. Then after a few days un-powered, same thing.

Somehow I found these memory chip grabber type devices. They were not easy to find. I have 3 left... Now I have a removable memory chip. I've swapped a few and it seems to be holding up. The part is called a "SOP28 to DIP28 Socket Adapter Converter Programmer IC Test Socket TEUSXI rtdn".

Am I nuts for doing this? Is there a much easier way with a mod chip and red cart or to just get the MODE and swap memory from an SD card? I just feel like $250 is too much for the MODE.

[zyrobs]

Bloody insane, I love it.

But yeah, why not just use a backup cart?

[Yart]

I've lost tons of save files from drop kicking my Saturn before. It's too easy to accidentally sail across a room with both feet in the air and land directly on the front of the memory cartridge.

Honestly though I love the idea of the external chips being accessible and switchable. You could dedicate the cartridge slot to a RAM cart too.

[captainkael]

May 7, 2021 23:10:02 GMT Yart said:

I've lost tons of save files from drop kicking my Saturn before. It's too easy to accidentally sail across a room with both feet in the air and land directly on the front of the memory cartridge.

Honestly though I love the idea of the external chips being accessible and switchable. You could dedicate the cartridge slot to a RAM cart too.

Yart you trying to pin your saturn to win a championship or something? xD