Re: [B2-devel] Macintosh memory information?

[Frank T. <fra...@gm...>]

I think that you need the PowerPC edition/addition of Inside Macintosh. I
will try to check on this in a few hours. I believe that there is a copy
available on-line somewhere, but I can scan the pages that you need if not.

On Wed, Jul 18, 2012 at 7:21 AM, Alexander von Gluck
<kal...@un...>wrote:

> Does anyone have any documentation on the memory layout of the old world
> Macintosh? (Performa 6400 era)
>
> I've been looking to rework how SheepShear manages memory and it's not
> completely clear to me how it does
> it's memory translation.  Most of the bugs I've seen on x86_64 are due to
> the exact memory mapping on emulated
> powerpc systems (eg, hard coded memory addresses we *have* to map for
> things
> to function) and something getting mangled
> on x86_64.
> https://github.com/kallisti5/sheepshear/issues/15#issuecomment-7045089
>
> I see memory maps for the really early Mac's, but am failing to find
> anything for the later old world machines
> online or in the old Macintosh service manuals.
>
> Here is what I know for a fact looking at the code:
>
> Low memory area, - 0x0        - 0x3000  (static 1:1 host:guest location)
> RAM,               0x0        - (memory size selected less then 1GB)
> ROM,               0x40800000 - 0x40C00000 (4MB mac rom)  (static 1:1
> host:guest location)
>
> Real addressing == "normal" allocation where memory locations are dynamic,
> and we translate addresses to match
> Direct addressing == memory is directly addressed, mostly used on native
> PowerPC?
> Nat_mem offset == ???, guessing it's for native PowerPC
>
> It looks given the code below that the Macintosh has to be patched to use
> the host memory
> addresses vs the emulator doing the memory translation (SheepShear acting
> as
> a mmu to the guest)
>
> https://github.com/kallisti5/sheepshear/blob/master/src/kpx_cpu/src/cpu/vm.hpp#L185
>
> The reason I ask here is because these changes could be pulled upstream to
> SheepShaver.
>
>   -- Thanks!
>     Alex
>
>
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