ABox
Under the Quark kernel a PowerPC native reimplementation of the OS known from the Commodore A1000, A500(+), A600, A2000, A1200, A3000(T) and A4000(T) systems runs as a mixture of a virtual emulation and a driver. This OS driver is called as ABox.
The 68k emulation is written in C and uses gcc assembler macros where necessary to speed up certain complex instructions. Even though the emulation is written in C, its structure is on a level where handcoded assembler isn't significantly faster.
A JIT (Just In Time) engine called Trance for MorphOS to speed up old 68k programs beyond the current state of the traditional emulation is also available.
The PPC native Exec supports the PowerPC register model which means there's no difference for this Exec if it runs 68k or PowerPC code. PowerPC code does not block multitasking inside the OS box like in emulations where the 68k code is just emulated in some host system's task (then every access outside this environment would stop the multitasking in the emulated environment).
For applications running under this new PowerPC A-Box kernel 68k code runs as subroutines inside PowerPC tasks. For 68k or PowerPC applications it's completely transparent if some library, hook, interrupt is still 68k or already using PowerPC code.
Early in its development, there was a relatively common misconception that the Quark Microkernel in MorphOS is related to or borrowed from the QNX operating system. This is entirely false.
Read more about this topic: Quark (kernel)