8 Mb CHIP RAM on All Amigas

[motorollin]

The 2MB chipmem on real Amigas is a hardware limitation. As DamageX said, if you want to increase the chipmem then you have to replace the hardware.

With WinUAE, they have adjusted the emulation so it can access more memory than a real Amiga, which is why you can have 8MB of chipmem.

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moto

[motorollin]

To summarise for those who can't take the hint :-)

1. The custom chips are physically only able to see a maximum of 2MB of chip RAM.

2. The only way to change 1. is to replace the custom chips and make extensive changes to the motherboard. Since nobody has the plans for the custom chips, I don't think replacements will ever be available.

3. Since the allocation of memory isn't handled by an MMU, you cannot swap memory out.

4. Even if it was possible to use software to swap memory out, this would require the OS to be running. As soon as you run software which turns off the OS (read: a game), you lose your swapping ability, and you're back to 2MB of chip RAM.

5. This idea of emulating the chip RAM is silly. How would your software know it is supposed to use the emulator when it wants to use some chip RAM? It wouldn't, so it would just address the chip directly and totally ignore your emulator.


I understand this dream, as it would be great to lose the distinction between chip and fast mem, and pool all available RAM for use by any software or hardware. But sadly, it's just not possible. If you really, absolutely must have more than 2MB of chip RAM, use UAE.

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moto

[motorollin]

@Tricky
How would existing software know how to swap memory out of chip RAM to free up space?

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moto

[motorollin]

@Tricky
So you're saying if you are running low on chip mem and want to run an application which requires more chip mem than you have free, you could MANUALLY put an application which is using chip mem to sleep, which would suspend its execution and move all of its memory from chip mem to fast mem?

That might work, but the problems will start when you want to wake the application up again and something has filled the chip mem with data. Even if there were enough bytes free to move the sleeping application back in to chip mem, because there is no memory management, how could you guarantee that the re-awoken app would be able to find all of its data in RAM again, once it had been moved back to a different location in chip RAM?

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moto

[motorollin]

I'm starting to think this thread is a wind-up :lol:

@leirbag
Please, please prove us all wrong by re-designing the custom chips, rewriting kickstart and extensively modifying an A4000 motherboard. When I see the board, and watch the machine boot with no startup sequence and report 8MB of chip RAM, then I will believe it is possible :roll:

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moto

[motorollin]

The files you are opening, are the opening on to an RTG screenmode, or a native Amiga screenmode?

If they are opening on an Amiga screenmode then the app may use chip RAM. Try FBlit, it may be able to move the graphic in to fast RAM. Alternatively, open the graphic on an RTG screenmode and it should use fast RAM.

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moto

[motorollin]

whiteb wrote:
if someone was to give Dennis the specifications so he can apply them to the Agnus section of the Minimig core.

They don't exist...

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moto