Hi!

I just stumbled onto this in a forum about BSOD in winblows:

>> "here is a random thing i found tho, my bios says that my video card is a 128mb card, and my ATI CATYLIST control center states that my card is for sure the 256mb one."

> "This may be because the video card uses shared memory. 128 MB is dedicated, but the other 128 MB is shared with the system memory. That is how mine works."

Perhaps that is why the developers have been unable to make all 256MB available. There simplay aren't 256MB on the card, only 128MB physical memory!

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- Don't get fooled by my avatar, I'm not like that (anymore, mostly... maybe only sometimes)
> Amiga Classic and OS4 developer for OnyxSoft.

@Deniil715

Quote:

Perhaps that is why the developers have been unable to make all 256MB available. There simplay aren't 256MB on the card, only 128MB physical memory!

The 128MB limit was introduced in OS4.1, prior to that I had access to the full 256MB. IIRC the limit was introduced because some cards had 2 banks of RAM which apparently caused stability problems when the second bank was accessed.

@Deniil715

That's nothing new in PC / Windows world. I remember once buying a cheap 256 MB video-card. It caused a lot of trouble on the PC I installed it in so went to have a look for the cause. Turned out that it only had 128 MB on board but due to the AGP specification it was allowed to consume 128 MB of motherboard RAM as well. I tried to return the card as I felt that it didn't meet the specifications I did expect but got 0 as actually on the box in tiny writing there was a statement that the card only had 256MB when it could borrow 128 MB from the system. Rather expensive lesson learned back then.

It should, however, be possible to tell your system that the AGP can only eat the memory that's on the video card and should leave the system memory untouched.

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Back home...

@Rob

Quote:

The 128MB limit was introduced in OS4.1, prior to that I had access to the full 256MB. IIRC the limit was introduced because some cards had 2 banks of RAM which apparently caused stability problems when the second bank was accessed.

I know, but my theory is that the second bank actually doesn't exist on those cards but instead should be configured to use system RAM. Something developers maybe had no clue about, or could not get working properly which is why they took the easy way out by simply disabling the second 128MB.

I have such a card (256MB) and had often problems when viewing large pictures in PicShow. It appeared to overwrite random registers such as DPMS and other stuff.

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- Don't get fooled by my avatar, I'm not like that (anymore, mostly... maybe only sometimes)
> Amiga Classic and OS4 developer for OnyxSoft.

@Deniil715

Maybe a little of topic but can AmigaOS 4.x utilize 256 Mb Video RAM? I mean does it matter if you compare 128 Mb cards?

Well I know my Radeon 9200 has 256MB because I have it assigned as "other mem" (apart from 32MB for the Mediator). :)

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@Darrin

You can assign the memory of the graphics card as internal RAM on AmigaOS?

Last edited by Niolator on 03-Sep-2010 at 05:33 PM.

@Niolator

on OS 3.x you can with a Mediator (for example that has a 256MB Radeon). It will essentially be Zorro 3 RAM just like a ZorRAM card.

But I don't think it's available at power-on, it is added using a command from startup-sequence or user-startup.

With the ZorRAM the memory is added at power-on. But the speed in either case is about the same. The limit really is the Zorro 3 bus.

And I'm talking Zorro 3 here. with Zorro 2 you can add only about 8MB max...so not so useful.

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AmigaOS 4.x Beta Tester - Classic Amiga enthusiast - http://www.hd-zone.com is my Amiga Blog, check it out!