MiSTer FPGA Forum

So I bought a 128mb RAM module from eBay. It arrived today. I was informed in the New Comers forum it was pretty old but since it arrived today I thought I would check out how useful it was.

Well it's old, but it seems worse than that. I checked the RAM ICs and dead short on 3v and Ground! Glad I checked before it went anywhere near my Mister! Unless something elementary has escaped me +3v and Ground should not be so intimately involved!

Here is a picture of the little bugger! Haven't got enough hands to show the short but it's there, trust me!

I don't even recognize that PCB design for the sdram.

I'd never seen it before but I think it was rickdangerous who informed me it was an old XXS module and that it wouldn't work with certain cores. It's the same RAM as current boards, so I thought I would test it out and make sure it worked first then probably reuse the ICs to make an up to date one. Obviously I needed to make sure it was working before hand.

So glad that I dug out the multi meter before hand. It would have been upsetting to say the least if it had blown the 3v regulator on such a hard to find dev board.

The seller has kindly offered me a refund so that's a relief!

aberu wrote: ↑Mon Jun 13, 2022 8:33 pm I don't even recognize that PCB design for the sdram.

https://github.com/MiSTer-devel/Hardware_alternative

Possibly should be stated design not be used is obsolete on github.

It is known to not be reliable with certain cores due board routing issues if I remember correct, the design was by antonio villena.

Ah! I searched high and low and couldn't find any info on this board! I did find one picture that helped with knowing which way round it needed to be installed if I had gotten that far.

I had originally intended to solder a v2.9 board myself but spotted the XXS board on eBay and figured I'd save myself some soldering. The cost of the board was roughly the same as the ICs from digikey with shipping etc so I thought at worst I could transplant the RAM.

Unfortunately the blank PCB still hasn't arrived yet anyway. In fact, it hasn't been marked as shipped on eBay and I haven't heard back from the seller.

Looks like I'm stuck on 32mb for a while yet!

Ah yeah, this module won't be compatible with the fast paging that is used in the upcoming Saturn core I believe.

Saturn is definitely another core I want to use, I've not actually checked if my current 32mb is enough to be honest. I kinda just want my Saturn console to enjoy it's retirement in good health and get the reasonably authentic Saturn experience from the Mister! I'm also looking forward to some Atari Jaguar goodness without the need to keep the original hardware setup and vulnerable to dust and cat related incidents!

aberu wrote: ↑Mon Jun 13, 2022 10:52 pm Ah yeah, this module won't be compatible with the fast paging that is used in the upcoming Saturn core I believe.

The 4 chip ram version also not working currently

https://github.com/srg320/Saturn_MiSTer/issues/1

This is the price of deviating from the schematics. It's really unfortunate that sellers try to shave off a dollar here or there with cheaper chips and by modifying the design to the detriment of their customers.