[CDG5] MemRetry's objective

[Elliot Nunn]

Very doable. But we’d need a bug to fix XD.

> On 2 Apr 2019, at 8:21 am, Daniel B-J <danielbj314 at verizon.net> wrote:
> 
> Do we know enough to make custom linked patches or ROM vector updates? It just seems too cool to not learn how to use.
>> On Apr 1, 2019, at 8:13 PM, Elliot Nunn <elliotnunn at fastmail.com> wrote:
>> 
>> Wow! It would be brilliant to have an accurate OldWorld Power Mac
>> emulator. Once I (finally) get Cube-E building, I hope to develop/RE a
>> minimal patch to get it running on RISC.
>> 
>> Slight twist (and apologies for being off topic): I just found that the
>> linked patches (lpch resources etc) hardly changed from System 7.1 to
>> Mac OS 8.1 (after which I think they disappeared). This is probably
>> explained by Apple using SuperMario, with its ROM vectorisation
>> mechanism, for all late-Quadra and Power Mac ROMs, and thus obsoleting
>> the linked patch mechanism. As they stand, then, the linked patches are
>> a powerful and modular instruction book for "modernising" or "System
>> 7-ising" any Mac ROM as far back as the first "128K" Plus ROM. Neat!
>> 
>>> On 2 Apr 2019, at 7:51 am, Max Poliakovski <maximumspatium at googlemail.com> wrote:
>>> 
>>> Wow! I call it a "real quick" reply :)
>>> 
>>> Mainly misaligned accesses. An emulator might not complain about these, but I would expect MAME to be pretty accurate!
>>> 
>>> So PPC load/store instructions will cause DSI on misaligned access and memretry will magically fix that? That sounds cool :)
>>> I don't actually know how the emulated CPU in MAME handles misaligned accesses. Tomorrow I'll try to enforce it to see what happens...
>>> 
>>> Does MacOS for PowerPC boot in MAME?
>>> 
>>> Currently it doesn't because MAME's emulation is still incomplete. Two years ago, I sent them several patches fixing CPU emulation so their model of a PowerMac 6100 almost reaches the gray screen. A hardware emulation issue related to CUDA/NVRAM is currently preventing it from booting - it seems that external interrupts won't be routed as expected. That causes the Netboot driver to hang forever. I think I'll be actually able to fix it...
>>> 
>>> Cheers
>>> Max
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>> 
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