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avatar_PulkoMandy

Gemini 1MB RAM expansion for Amstrad Plus

Started by PulkoMandy, 20:34, 08 October 22

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TotO

#50
@zhulien You can found a lot of informations about the ASIC from here:
http://quasar.cpcscene.net/doku.php?id=assem:asic

And here about the GA and ASIC:
https://www.grimware.org/doku.php/documentations/devices/gatearray

EDIT: Hum... The ASIC related links (unlock sequences, ...) seem to not work on Grimware. :(
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

zhulien

i wonder if a future ram expansion with 2mb sitting in the ROM space would be worthwhile?  the upper 128 ROM slots.

TotO

Quote from: zhulien on 15:09, 12 October 22i wonder if a future ram expansion with 2mb sitting in the ROM space would be worthwhile?  the upper 128 ROM slots.
From &80 (up to 32 ROM), it is the cartridge area for the Amstrad Plus / GX4000 and compatible.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

zhulien

Quote from: TotO on 15:10, 12 October 22
Quote from: zhulien on 15:09, 12 October 22i wonder if a future ram expansion with 2mb sitting in the ROM space would be worthwhile?  the upper 128 ROM slots.
From &80 (up to 32 ROM), it is the cartridge area for the Amstrad Plus / GX4000 and compatible.
Any reason it cannot be both?  by default a cartridge, write to an IO port it becomes RAM?

TotO

Quote from: zhulien on 15:11, 12 October 22Any reason it cannot be both?  by default a cartridge, write to an IO port it becomes RAM?
And why not 2MB to the RAM area to be compatible with the existing? ;D
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

zhulien

Quote from: TotO on 15:15, 12 October 22
Quote from: zhulien on 15:11, 12 October 22Any reason it cannot be both?  by default a cartridge, write to an IO port it becomes RAM?
And why not 2MB to the RAM area to be compatible with the existing? ;D
Because when it is mapped in at C000, that 2mb won't have any DMA issues.  and, we might then be able to have 6mb on CPC.

zhulien

Quote from: zhulien on 15:16, 12 October 22
Quote from: TotO on 15:15, 12 October 22
Quote from: zhulien on 15:11, 12 October 22Any reason it cannot be both?  by default a cartridge, write to an IO port it becomes RAM?
And why not 2MB to the RAM area to be compatible with the existing? ;D
Because when it is mapped in at C000, that 2mb won't have any DMA issues.  and, we might then be able to have 6mb on CPC.
Which makes me wonder... why not make a 16mb RAM expansion that sits at C000 on CPC - it's 2022, we need 16mb software now.

TotO

Quote from: zhulien on 15:16, 12 October 22Because when it is mapped in at C000, that 2mb won't have any DMA issues and, we might then be able to have 6mb on CPC.
May be nice start to use your Play2CPC hardware so?  :-*
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Maniac

Quote from: zhulien on 14:51, 12 October 22I have a plus version of the multiface 2, but i am unsure what is done to it to make it work other than the form factor (now an mx4 card).
The Plus version of the Multiface 2 was amended to support the Centronics connector and the revised version of AMSDOS. It does support any of the enhanced Plus features such as sprites etc. If you use the Stop button when running Plus software and return (in my experience) to the game it usually crashes.

PulkoMandy

Quote from: zhulien on 15:17, 12 October 22
Quote from: zhulien on 15:16, 12 October 22
Quote from: TotO on 15:15, 12 October 22
Quote from: zhulien on 15:11, 12 October 22Any reason it cannot be both?  by default a cartridge, write to an IO port it becomes RAM?
And why not 2MB to the RAM area to be compatible with the existing? ;D
Because when it is mapped in at C000, that 2mb won't have any DMA issues.  and, we might then be able to have 6mb on CPC.
Which makes me wonder... why not make a 16mb RAM expansion that sits at C000 on CPC - it's 2022, we need 16mb software now.
In my case I am limited to 1MB by the availability of RAM chips that can work with 5V signals. Larger chips would require an electrical level conversion from 3.3 to 5V. I think some other hardware (Duke M4?) works with 3.3V components so they may be able to do it.

But there is no real need for this much memory, or if there is, maybe you should not be using a CPC? :) (that's my personal opinion, so I don't plan to design such hardware, someone else is free to do it if they want to).

eto

#60
Quote from: zhulien on 15:17, 12 October 22it's 2022, we need 16mb software now.
Addressing 16MB is not the problem. We could probably find another register where can we store another 8 bit, so we could address 1GB of RAM. Maybe the additional I/O that the AY-3-8910 adapter provides?

But what would you do even with 16MB of RAM? A few days ago we struggled to find a use case for 4MB.

TotO

Quote from: eto on 17:23, 12 October 22Addressing 16MB is not the problem. We could probably find another register where can we store another 8 bit, so we could address 1GB of RAM. Maybe the additional I/O that the AY-3-8910 adapter provides?
Usually, I answer that is not a problem to address 4GB RAM... But you will require one year to fill it.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

GUNHED

#62
Fist of all: Congratulations to this great project!
Somehow this was missing for the 6128plus (or 464plus).

About the discussion: In my opinion everybody (software person or hardware person) should do always the best possible. Means...
Software: Catch possible problems and omit them
Hardware: Define your product for a target, try to omit problems
If we all agree to do the best then everything will be fine.

Of course often single persons want to push their products (software or hardware) and that's what one can see on their comment. Well, it's ok to have different POV's. Why not. But it's getting nasty when somebody defines a rule for all CPC and Plus scene. Maybe (even here) we can be a bit more of a team. :)

From what I did read, it's probably not too expectable that there will be a 4 MB version of this great piece of work.

Or is there any chance of a 4 MB Gemini RAM expansion in some future?
(asking because I seriously use/need it for work).
http://futureos.de --> Get the revolutionary FutureOS (Update: 2023.11.30)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

Prodatron

Now I am just curious, does that mean that your futureos is crashing with a normal memory expansion on a CPC plus with plus features enabled?

GRAPHICAL Z80 MULTITASKING OPERATING SYSTEM

PulkoMandy

I could do a 4MB version but it would need 4 RAM chips and I think a bit more logic on the board (I need to store and decode one extra address bit). The RAM chips are not super easy to get at the moment due to global shortages and logistics problems. So for now I'll focus on this 1MB version and hope that Lyontech or some other manufacturer starts or resumes production of a 2MB chip in the future, then I can do a 2MB version.

I should have ordered these chips when they were available...

zhulien

I'd like a 4mb version if you eventually make them.  I think the RAM expansion is a good one, i'd also like a 16mb RAM expansion (even if not made by yourself) that maps into C000 behaving somewhat like writable ROM and avoids the DMA issue completely.  The reason for this is not only for machine code applications, but it is more convenient for BASIC programs that use RSXs (located just under himem) to access that RAM so that we can have almost 42k basic programs instead of 16kb (paging between &4000 - &8000).  Of course no existing software will use it, future software would.

TotO

Got 64K, want 256K. Got 512K, want 2MB. Can got 4MB, would like 16MB... Next?  ;D
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

asertus


PulkoMandy

But is there any software that really makes use of it? Because the list of software on that Wiki page is just memory testers... If that's all you want to do, it's easier to write software that just pretends the memory is there and working fine  ;D

eto

From the sellers homepage:

"How you use the vast space is up to you."

So not even the seller has an idea what to do with it ;-)


Prodatron

#70
Quote from: PulkoMandy on 13:10, 13 October 22But is there any software that really makes use of it? Because the list of software on that Wiki page is just memory testers... If that's all you want to do, it's easier to write software that just pretends the memory is there and working fine  ;D
On the MSX a memory expansion (called "Memory Mapper") can have a size of up to 4MB (= 256 x 16KB), and this catridge includes 4 of them (one for each sub slot).
Some weeks ago the biggest game ever made for the MSX has been released, which has a size of 36MB (!). Even this "only" requires 512K of RAM.
Youtube: youtu.be/3C_W_AwSGII (copy this link manually)

If someone shows me a real working example of a software, which does useful things with so much RAM (>1MB) which can't be done with a mass storage device, I would be convinced. All I see now are video- and audio-streams or theoretical blah blah.

GRAPHICAL Z80 MULTITASKING OPERATING SYSTEM

zhulien


asertus

I have not seen any real use of > 512kb in an MSX. Even GB emulator requires only 256kb but it says they can use up to 4mb.

http://www.tni.nl/products/gem.html

In my opinion, even MSXs require normally less RAM than Amstrad, as they have separated video Memory and normally can read directly all resources required in the game from the cartridge..

HAL6128

Quote from: Prodatron on 14:55, 13 October 22If someone shows me a real working example of a software, which does useful things with so much RAM (>1MB) which can't be done with a mass storage device, I would be convinced. All I see now are video- and audio-streams or theoretical blah blah.
SymbOS could be a serious candidate.
...proudly supported Schnapps Demo, Pentomino and NQ-Music-Disc with GFX

Prodatron

Quote from: HAL6128 on 15:41, 13 October 22SymbOS could be a serious candidate.
Problem is, in some parts of the SymbOS kernel addressing is currently limited to 20bits (16 + 4), which is 1MB.
Maybe it is possible to extend it to 24bits (most functions already work with 24bits), but then old software had to be executed inside the first 1MB.

GRAPHICAL Z80 MULTITASKING OPERATING SYSTEM

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