Gemini 1MB RAM expansion for Amstrad Plus

[GUNHED]

Hi. Has anyone tested the Gemini 1MB card with CPM+ for a RAM DISK? It's totally unstable for me. The CPM+ recognizes the RAM and mounts the C: drive but it always ends up crashing after seconds or minutes of use. The card seems OK because the RAM tests are conclusive.

Note that it crashes even if I don't access the c: drive. I doubt that it's a CPM+ configuration problem (bad EMS?) because it works well with Caprice 64 or WinApe emulators. The card seems OK because the RAM tests are conclusive. What could it be ?

Configuring the card in 512kB or 1MB does not change anything.

Well, first of all. Forget about emulators. Lots of things work there, but not on the real machine. That's especially true for hardware expansions.

The Gemini works well for me on 6128plus. And also on CPC6128.

Can you please tell exactly about your system-setup and you PSU (Volts and Ampere)?
Does native OS and FutureOS work well?

[Nas_Sutromi]

Is the memory expansion still available? I'm from Portugal, do you ship from Europe?

[PulkoMandy]

Yes, still available and shipping from France

[orzel]

The schematics and Kicad file are available if someone wants to ...

Hello,

Where could those be found ? I'm interested in the kicad files and PALs 'sources'.

You linked to https://pulkomandy.github.io/shinra.github.io/gemini.html, but i can't find anything there. There's a sentence "all the needed design files are available", but without any link either.

[PulkoMandy]

You can get the git repository with all my electronics stuff here:

git clone "https://pulkomandy.tk/gerrit/avrstuff"

Or browse online:

https://pulkomandy.tk/gerrit/plugins/gitiles/avrstuff/+/refs/heads/main/CPC%20stuff/gemini/

I will add links to the webpages.

[orzel]

git clone "https://pulkomandy.tk/gerrit/avrstuff"

This gives me a blank page with just "Not Found" in there.
The other link works. But I can't git clone ssh://pulkomandy.tk:29418/avrstuff
It stalls quite a while and then says "This key is not known by any other names", and even after confirming I accept it, it then fails with "permission denied"

[PulkoMandy]

That's why I wrote that you can use:

git clone "https://pulkomandy.tk/gerrit/avrstuff"

Only with git clone. If you try that address in a web browser, it won't work. But it will for git.

The ssh URL for git clone works only if you have set up an account on my server and set an ssh key.

[orzel]

git clone "https://pulkomandy.tk/gerrit/avrstuff"

Yeah. Oops. Sorry !
I confirm it works.
Then i can see kicad files in "CPC stuff/gemini".
(a lot of unrelated stuff in this repository, nope ?)

[orzel]

The sram "ly6220488" is not easy to source, right ? (not a critic, just checking the design).

It's not available at mouser/digikey/aliexpress/lcsc..

[PulkoMandy]

The repository has all my electronics projects. There were no reason to split it so far.

If there is interest in making separate repositories for some things, I can do it.

The RAM was available from Farnell last time I needed it, but it seems it isn't anymore: https://fr.farnell.com/lyontek/ly62w20488ml-55lli/sram-16m-2mx8-2-7-5-5v-44tsopii/dp/2253669

You can use any RAM in the same pinout and that supports 5V supply. There are some from Infineon (CY62158ELL), from Alliance ( AS6C8008), ...

I think Lyontek however is the only one to offer a 2MB one. The other manufacturers stop at 1MB.

[orzel]

You can use any RAM in the same pinout and that supports 5V supply. There are some from Infineon (CY62158ELL), from Alliance ( AS6C8008), ...

I think Lyontek however is the only one to offer a 2MB one. The other manufacturers stop at 1MB.

Ok. Great. Thanks for the information (and the repository).

[eto]

Regarding 1MB vs 2MB: Is there any software that benefits from 2MB over 1MB? Afaik there is either some tech demos that need the max. of 4MB - or basically SymbOS with a max. of 1MB. 

[orzel]

I'm wondering too. I understand lot of software don't even use the extended 64k. I'm pretty sure the first 512k are useful (for alternative os, disk copying, and such). But above 512k... ?

[eto]

I'm pretty sure the first 512k are useful (for alternative os, disk copying, and such). But above 512k... ?

SymbOS can benefit from 1MB. With "just" 512K it's possible that you run out of memory. With 1MB it's still possible but imho only if you specifically force a situation where you hit the 1MB limit.

[PulkoMandy]

I don't know myself 

Some people asked for it so I made it. There is even some demand for a 4MB version. I think FutureOS could make use of that. Maybe FUZIX as well, but there each app is limited to 64K, so you would have to be doing a lot of multitasking.

[Prodatron]

Fuzix is limited to 1MB as well.
I am planning to introduce a new memory allocation system in SymbOS, that is using the RAM behind the first 1MB only for storing data (not for code), but it's already really not easy to fill the whole first 1MB.