By: Ungo (a.delete@this.b.c.d.e), June 24, 2020 12:49 am
Room: Moderated Discussions
hobold (hobold.delete@this.vectorizer.org) on June 23, 2020 1:07 am wrote:
> Apple's history of transitions, both m68k -> PowerPC, and PowerPC -> x86, did follow the script
>
> 1. have a complicated and unreliable translator that works good
> enough for stage presentations and very simple programs
>
> 2. quickly abandon the translation layer before it ever learns to deal with the hard cases
>
> Been there, observed that. Twice.
>
> You know how the saying goes: "Any sufficiently advanced technology is indistinguishable from a rigged demo."
The m68k emulator worked quite well, in my experience, and was never removed from "classic" MacOS, not even when the whole thing got poured into a mildly sandboxed compatibility process running on top of OS X.
They couldn't easily get rid of m68k emulation. The original PPC Macs shipped with a version of MacOS that hadn't even been fully translated to PowerPC! This was because so much of the Mac Toolbox was carefully hand-optimized m68k assembly; it was too difficult to port it all right away. This meant that even native PowerPC apps frequently called into m68k system libraries.
IIRC over time they converted more and more of the Toolbox to be fully native, but the emulator stayed until they discontinued support for the Classic environment altogether. I'm pretty sure that happened about 10 years after the first PowerPC Mac shipped, so I'm not sure how you remember that as a quick abandonment.
Also, I remember at least two major revisions of the m68k emulator. The original was a simple jump table emulator and the later replacement was a JIT, which greatly improved performance.
> Apple's history of transitions, both m68k -> PowerPC, and PowerPC -> x86, did follow the script
>
> 1. have a complicated and unreliable translator that works good
> enough for stage presentations and very simple programs
>
> 2. quickly abandon the translation layer before it ever learns to deal with the hard cases
>
> Been there, observed that. Twice.
>
> You know how the saying goes: "Any sufficiently advanced technology is indistinguishable from a rigged demo."
The m68k emulator worked quite well, in my experience, and was never removed from "classic" MacOS, not even when the whole thing got poured into a mildly sandboxed compatibility process running on top of OS X.
They couldn't easily get rid of m68k emulation. The original PPC Macs shipped with a version of MacOS that hadn't even been fully translated to PowerPC! This was because so much of the Mac Toolbox was carefully hand-optimized m68k assembly; it was too difficult to port it all right away. This meant that even native PowerPC apps frequently called into m68k system libraries.
IIRC over time they converted more and more of the Toolbox to be fully native, but the emulator stayed until they discontinued support for the Classic environment altogether. I'm pretty sure that happened about 10 years after the first PowerPC Mac shipped, so I'm not sure how you remember that as a quick abandonment.
Also, I remember at least two major revisions of the m68k emulator. The original was a simple jump table emulator and the later replacement was a JIT, which greatly improved performance.
