About multitasking, what's best : AmigaOS, Linux, or Winblows XP ?

[Zac67]

IMHO AmigaOS performs better than Windows XP & Linux because it features a more modern microkernel.
Windows NT/2k/XP/2k3 started out as a micro kernel, but was evolved into a hybrid.
OS X shares the same fate, but to a much lesser degree.
Nearly all Un*x flavors use a monolithic kernel that actually caused Linux to scale very badly when it came to SMP some years ago.

[Zac67]

The 68010 was especially designed to be used with the 68841 MMU - but the MMU would have put an additional wait state on the memory. Plus the additional overhead needed for memory protection would've made quite a bit of a difference (context changes are far more extensive).

Message passing could've been done by allocating 'public' memory and then passing a pointer - of course this would have caused one tiny bit of less memory protection. ;-)