68K Access Under OS4

[Karlos]

So Karlos, have you worked with the 68K or even accessed it at all from OS4? I know you have a lot of experience working with the PPC from 68K code but was curious if you've done anything from OS4 regarding the 68K?

Afraid not. It was simply a thought experiment, one that would likely require quite a lot of work to evaluate the feasibility of. As interesting as the idea seems to me for now, there are more pressing things to work on (in the limited time I have in the day in which to cram it in).

[nyteschayde]

Sure, I understand you're busy. I'm so fragmented with my time as well I never seem to get anything done. Just was curious on your level of experience with the OS4->68K usage as opposed to your past experiences.

[Matt_H]

Theoretically, ShapeShifter should work at full speed using the OS4 68K JIT, since ShapeShifter is more in line with today's virtual machines like VMWare and Parallels than a true emulator, since it uses the host's own CPU as-is and just emulates the additional bits. If it doesn't work, it's probably due to limitations of the OS4 JIT (it doesn't emulate everything). The 68K BasiliskII might be a better test under OS4, since I think it's a little "cleaner" on the hardware-banging side (and also doesn't emulate the CPU).

Point being, there could also theoretically be a version of 68K UAE built the same way - use the native CPU instead of emulating. I'm not sure how big a project that would be. Maybe adapting the in-program JIT for PPC is easier!

[stefcep2]

Theoretically, ShapeShifter should work at full speed using the OS4 68K JIT, since ShapeShifter is more in line with today's virtual machines like VMWare and Parallels than a true emulator, since it uses the host's own CPU as-is and just emulates the additional bits. If it doesn't work, it's probably due to limitations of the OS4 JIT (it doesn't emulate everything). The 68K BasiliskII might be a better test under OS4, since I think it's a little "cleaner" on the hardware-banging side (and also doesn't emulate the CPU).

Point being, there could also theoretically be a version of 68K UAE built the same way - use the native CPU instead of emulating. I'm not sure how big a project that would be. Maybe adapting the in-program JIT for PPC is easier!

Has anyone actually got 68k Basilisk 2 to boot into MacOS on an amiga

[bbond007]

Is it possible to access the 68K processor from OS4 just like we were once able to access the PPC from OS3.x? Basically RunInUAE is a great idea but is more or less completely unusable under OS4 Classic (at least with my BlizPPC).

It kills me I have a 68060 sitting there dreaming while the 603e struggles to emulate a 68K for E-UAE. Any chance of passing through to the real 68K (ala ShapeShifter for MacOS, etc...)

It might be possible but there are a few things you may need to consider.

Shapeshifter is not emulating the MAC's video hardware in the same sense that UAE emulates the every detail of the Amiga's chipset. Apple has an abstraction layer on the hardware (QuickDraw) and Shapeshifter patches into that.

The slowness with UAE may not even be the CPU emulation anyway. The bottleneck is far more likely emulating the custom chipset.

Finally, the architecture of UAE. For example the custom chip emulation may require hooks into the CPU emulation.

[klx300r]

sounds like the problem are crooks bored to post on moo****ingbunny lately!

geez and you're surprised ? it's the norm here on every single OS4 thread sadly:(

[nyteschayde]

It might be possible but there are a few things you may need to consider.

Shapeshifter is not emulating the MAC's video hardware in the same sense that UAE emulates the every detail of the Amiga's chipset. Apple has an abstraction layer on the hardware (QuickDraw) and Shapeshifter patches into that.

The slowness with UAE may not even be the CPU emulation anyway. The bottleneck is far more likely emulating the custom chipset.

Finally, the architecture of UAE. For example the custom chip emulation may require hooks into the CPU emulation.

That may be, but other than the amount of work it would take to tap into the existing chips (and I understand there may be work there that is not easy; i.e. securing direct access to the chipset if that's even possible), all those custom chips are actually available and shouldn't need emulating. It's likely that the E-UAE Amiga port simply did the least amount of work as possible and avoided using the real hardware even though it does exist and is within easy reach.

Emulating an Amiga on an Amiga should be a fast process.