15 March 2008, 14:11 | #1 |
Computer Nerd
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Need virtual memory for chip mem.
Hi there,
Does anyone know of a virtual memory system which allows paging chip mem? The idea is to page the chip data to a ramdisk in fast memory. I've tried it with VMM, but that doesn't work (maybe I got it wrong somehow). Also, does anyone know if it's even possible with a Blizzard '030? Thank you for your time. |
15 March 2008, 15:09 | #2 |
WinUAE developer
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Impossible. Custom chipset DMA bypasses CPU (and MMU) completely. It would not be "chip RAM" anymore.
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15 March 2008, 16:23 | #3 |
Ya' like it Retr0?
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@Toni
What trick do you use to allow WinUAE to have 4mb of chip, and could this be implemented in hardware in some way? |
15 March 2008, 17:29 | #4 | |
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Quote:
"Virtual" Agnus can do anything you want it to do. DMA from fast RAM? Can do. DMA via MMU. Can do. "Only" need some programming |
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15 March 2008, 18:44 | #5 | ||
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Quote:
I'm still curious though, how can the blizzards '030 bypass it's own mmu? Isn't chip mem simply part of the 4gig address space so that a mmu table can be setup to detect cpu chipmem access? Doesn't all this happen before the chipmem is accessed, or am I missing something completely? Quote:
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15 March 2008, 19:01 | #6 | ||
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Quote:
Quote:
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16 March 2008, 08:21 | #7 | |
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Quote:
Thanks for explaining |
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28 March 2008, 15:06 | #8 |
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Sorry to bring this up again, but I just had to say something about the commodore 64 style bank switching.
Electronically this should be quite possible. There should be no reason why it's impossible to put some sort of bank switching hardware between chipmem and the custom chips. This system could then be used in a new os, or an os such as linux, which would have to be modified to use the feature. This system only has one drawback, and it's that the software has to know beforehand that a certain bank is going to be needed. This means it's difficult at best, if not impossible to make AmigaOs use the feature. Now, I am 99% sure I'm right here So Toni, please don't be so quick to say no, when technically it's probably possible |
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