On Sun, 06 Feb 2000 18:20:58 +0000, Peter Gordon (mrtickle@amiga4k.ndo.co.uk) wrote:
> Hello,
>
> I'm sorry but you appear to be speaking with an apparent authority despite an obvious lack of understanding of computer architecture...
ROTFL .... said it far better than I could ;-)
> > 1) The miggy gets turned on and all it will see will be an expansion card
> > with some memory.
> > 2) It uses the m/b's 020 to start booting.
> > 3) First thing in the start-up sequence is a command telling it to load a
> > 68k emulator off the hard-disk and into a space in memory.
>
> 68k on the hard disk? Yeah... that'll get the virus writers rubbing their hands :)
I hadn't considered that aspect - another reason to shout him down ;)
> > 4) A second command gets run that starts the 68k emulator.
>
> Errr... which would require the CPU's to have some form of bus arbitration and you get into the whole context switching thing. This would make the card very expensive as you'd have a whole load of hardware to manage a single context switch!!!
I tried to explain that to him and this email was his reply!!
> > 5) The 68k emulator *knows* there is a PPC chip on the expansion board and
> > starts using it.
>
> Crap. The 68k emulator doesn't *know *anything. Its just running on the G4.
In theory the 68k emulation could be programmed with some AI ...
> > 6) The 020, even tho the system knows it's there...becomes redundant.
>
> > It's really the only feasable way of doing it.
>
> Sorry, what language are you speaking there? Only it appears to be bollocks!
I think it's the bull$hit dialect ;)
> When you put a G4 card into a big box amiga, what CPU is going to load the 68k emulation exactly? There is no mobo CPU on big box amigas. None. Nada. Zip. Zilch. Zero.
Hey, I'd forgotten that, and I'm using an A4000! :)
> > To put it on a ROM chip on
> > the card itself, and have the card autoconfig itself as a CPU expansion
> > card isn't going to work, not unless they can get it to go through the ROM
> > before looking at the CPU.
>
> Hahaha! When you put +5v into the PPC, it will start up like any processor. Just make the startup vector point to a 68k emulation on a rom the local bus, and it'll start the moment you hit the on switch, before the card has even autoconfigured. So there. :)
Yup. Only way to do it. Easiest way to do it too. Thus an incredibly
sensible way to bloody do it!
Kev
--
Kevin "Redvers" Fairhurst - ICQ 56332267, redver5 on AIM
