A: Yes and no. An emulator emulating only the Motorola
680x0 CPU wouldn't be completely compatible with a
"real" Amiga. To some degree, directly or indirectly,
many Amiga programs, beginning from
the Amiga operating system, and even some file formats (e.g. because they reference some
Display ID, or like IFF-ANIM which makes assumptions about pixel
arrangements in double-buffering screen modes), rely on some
custom chip functionality. While it would be possible to re-write
the software, this is not in the spirit of emulation, and it would
be almost impossible to re-write all older software.
Also, it must
be considered that when a program does not make specific use of a
custom chip's functionality, this does of course not need to be
emulated, so there is little or no performance penalty (although
there is a certain complexity involved in maintaining the proper
timing and synchronization of the various custom chip components,
even if they are idle). Setting the Workbench screen or any other
frontmost screen to a Picasso96 mode (which, like all RTG modes,
does not use the custom chips) instead of an Amiga PAL or NTSC
mode (which use the custom chips) greatly improves the emulation
speed. Disabling audio in the emulation settings can also slightly
improve the speed of emulation.
Specifically emulating certain aspects of the
Amiga custom chips also allows the emulation software to recognize
certain specialized tasks, and better emulate these by using
similar and specific capabilities on the host environment, if
possible (e.g. for blitting, which for example is very fast using
the Picasso96 extensions for UAE, which are included under license
in Amiga Forever).
Also see:
- 3-119 - Speed
of Amiga Emulation
- 3-149 - Amiga
Emulation Software: Integration vs. Isolation and Amiga Forever vs. Other Packages
Please refer to the chapter on Emulation
for additional information.
