Dual SDRAM with Mixed Versions

[pgimeno]

I bought a 3.0 SDRAM module for use with the Saturn core, as I had a 2.5 and was experiencing crashes. It works fine now.

Now I'm wondering if I can use the 2.5 module in the second GPIO slot to have a dual SDRAM setup, but I have a couple questions:

• What are the cores that take advantage of (or only work with) dual SDRAM? I know there's a version of the PSX core that uses it, but which others?
• Are they equally demanding in both slots? Like, if the Saturn core can still be enhanced with dual SDRAM, does it also require a 3.0 module in the second slot?

The underlying question is whether I can get a dual SDRAM setup "almost for free" (at the price of a digital I/O board) now that I have the 3.0 module, using the currently retired 2.5 module, and what good will it be.

[FPGA64]

yes you can. I run a 2.9 in the primary and a 2.5 in the secondary. Always use the most modern in the Primary slot.

Follow this guide

https://misterfpga.co.uk/dual-sdram-mister-fpga/

As for cores there is the PSX with almost 0 Difference. Saturn , and the Dual Ram Jag core

The 2nd slot is not about capacity or speed. its just another channel that can be used.

[ItalianGrandma]

Yeah, I have a 2.9 in primary and a 2.5 in secondary slot. That said, nothing really takes advantage of it yet except the work in (seemingly stalled) progress Jaguar core. The PSX and Saturn cores have dual ram builds, but you won’t notice any differences in PSX and there aren’t really any differences for Saturn at this point either.

[DiamondDave]

I did the same thing as you (upgraded from 2.5 to 3.0 for improved Saturn) and didn't even bother going to dual ram as nothing requires it. The 2.5 is in a drawer.

[Chris23235]

Some cores have video issues for me with SDRAM I had two 2.9 modules and now I have one 3.0 and one 2.9 module. Regardless of the combination I get garbled video in the C16 and Atari ST core when DUAL RAM is enabled with the dip switch. If I disable the issues disappear.
No big deal for me as I use these cores on my MiST mainly, but if I would depend on these cores on the MiSTer it would be annoying.

[C-R-T]

Just sell the old one on Ebay, problem solved. Having two doesn’t make sense and probably never will.

[FPGA64]

Just sell the old one on Ebay, problem solved. Having two doesn’t make sense and probably never will.

As Usual CRT bias is showing. They have a passionate hatred about Dual Ram which they clearly see as a threat to Analog output. As such any advice they give on this subject should be tempered with the knowledge of their bias

[cursedverses]

which they clearly see as a threat to Analog output.

Well, I mean there's only one secondary GPIO slot so it's one or the other. And we're all going to have a different opinion on what is more necessary.

If you want Dual RAM, go Dual RAM. If you want Analogue, go Analogue. If you want neither, that works too. Just don't lash out at each other for it, they're all valid use cases.

[dickhardpill]

I can't wait for the new AD I/O board to be available.

[akeley]

They have a passionate hatred about Dual Ram which they clearly see as a threat to Analog output.

How can dual RAM be a threat when a completely new analogue board has just been designed, and nobody seems keen on stopping selling the old ones anyway?

Meanwhile, it's a fact of life that dual RAM has been vastly overhyped on the internets, and I bet many people who jumped on the "futureproofing" bandwagon would think twice if they knew what the actual use for it is in 2024.

[Chris23235]

Additionally to the I/O board it is possible to get an analog signal out of the HDMI port. You just had to use an HDMI2VGA DAC. Simply enable direct video in the MiSTer.ini and the MiSTer will send the analog signal through the HDMI port. I never understand, why people are ignoring this option. It is available for years now.

[FPGA64]

Additionally to the I/O board it is possible to get an analog signal out of the HDMI port. You just had to use an HDMI2VGA DAC. Simply enable direct video in the MiSTer.ini and the MiSTer will send the analog signal through the HDMI port. I never understand, why people are ignoring this option. It is available for years now.

And this is 24 bit which the analog board could not do until the rercent revision.

[akeley]

Direct Video is a fantastic option but it's not flawless. Finding a decent dongle can be quite a battle, and it's also incapable of displaying modelines without external add on.

But yes, overall it's an another argument against the "threat" theory.

[pgimeno]

Meanwhile, it's a fact of life that dual RAM has been vastly overhyped on the internets, and I bet many people who jumped on the "futureproofing" bandwagon would think twice if they knew what the actual use for it is in 2024.

Yeah, I never really even considered dual RAM before. It's only now that I get it "for free" that I wanted to know if it was viable to use the retired 2.5, and it seems it is. Given the answers on its uses and limitations, however (thanks @Chris23235 for the tip on the incompatibilities, by the way), I don't think I'll even try.

I was under the impression that there were a few unofficial cores besides Jag that also needed dual RAM. I also seemed to recall some WIP Jotego cores required it. No one has mentioned any of those, so I was probably wrong.

[FPGA64]

Jotego as far as I know never went dual Ram. The Smash TV experimental core needed it. I personally have not seen the issue reported by Chris23235 on my dual ram setup

[C-R-T]

Just sell the old one on Ebay, problem solved. Having two doesn’t make sense and probably never will.

As Usual CRT bias is showing. They have a passionate hatred about Dual Ram which they clearly see as a threat to Analog output. As such any advice they give on this subject should be tempered with the knowledge of their bias

This is the weirdest thing I’ve ever been accused of, and it did make me laugh.

I’m only biased against stupid wasteful FOMO behavior, which using dual ram is. You’ll never miss out with single ram, so lose that second stick.

I don’t even use an analog board since it’s a poor solution (until recently). I’ve been using direct video since day one.

[Chris23235]

Jotego as farr as I know never went dual Ram. The Smash TV experimental core needed it. I personally have not seen the issue reported by Chris23235 on my dual ram setup

Just out of interest. Did you specifically tried the ST and C16 cores on HDMI? Because for me it is 100% reproducable and if it is only for me, then it is my MiSTer that is at fault.

[FPGA64]

Jotego as farr as I know never went dual Ram. The Smash TV experimental core needed it. I personally have not seen the issue reported by Chris23235 on my dual ram setup

Just out of interest. Did you specifically tried the ST and C16 cores on HDMI? Because for me it is 100% reproducable and if it is only for me, then it is my MiSTer that is at fault.

On HDMI to a LG B9 Oled. Just retested both cores show no image corruption

[Chris23235]

Jotego as farr as I know never went dual Ram. The Smash TV experimental core needed it. I personally have not seen the issue reported by Chris23235 on my dual ram setup

Just out of interest. Did you specifically tried the ST and C16 cores on HDMI? Because for me it is 100% reproducable and if it is only for me, then it is my MiSTer that is at fault.

On HDMI to a LG B9 Oled. Just retested both cores show no image corruption

Thanks for testing, then I know it is something with my setup.

EDIT: I played around with the settings. It only applies once I try to run the C16 core in PAL. In NTSC everything is fine. When I disable the DUAL RAM with the Dip switch the PAL mode works too. Strange.