Amiga OS4 on classic amiga PPC questions

[Rogue]

i.e AOS4 on a CSPPC can access to CIAs for timings, making a lot of programs working again, even under AOS4 . . .is it right?

Yes. All custom hardware is available. The oldest program I was able to test under OS 4 was the "RoboCity" demo ;-)

[Rogue]

I doubt old demos and games work. Killing the OS is no longer option.

Stuff like RoboCity still works; most demos that try to do nasty things will probably fail, although I haven't tested them yet...

[Rogue]

IE :I mean, I have 040@33 and 280 Mhz 603, with Os4 installed on my setup, I would be able to run aga demos at 060 speed ( using 68k emu over PPC, i think it would get more speed than my real 040@33 )?

The question isn't so much one of speed (that is unpredictable and depends on how clever the demo is programmed, what instructions it uses etc) but rather of compatibility, i.e. does the demo mess around in system structures etc. Also, certain features of the CPU are no longer available in emulation. You can no longer rely on exception handling (although interrupts do work if you are using AddIntServer()) for example.

Since petunia emulates almost all the instruction of the 68060, and AFAIK the 68040 the BPPC cannt be directly touched by software anymore since Os4 is loaded..... (physical 680x0 is disabled by soft AFAIK)

The physical 680x0 in the Amiga is stopped once AmigaOS4 takes over.