Subject: Re: LC/Performa 475 boots (serial console)
To: Johan Claesson <Johan.Claesson@uab.ericsson.se>
From: Bill Studenmund <wrstuden@loki.stanford.edu>
List: port-mac68k
Date: 08/27/1997 12:29:54
> > How far did it get before it failed?
> > =
> 
> 
> [Preserving xxxxx bytes of...]
> 
> That's all it says!

Do other 475 owners see the same thing?

Since it's acting like an unknown model, should it be getting farther in the
boot before dying?

> Ok I see your point here, but I am not sure about how MacOS gives
> gestaltID:s to unknown machines.But the only machines you can accelerate
> the way I did is the LC 475 and LC III, right? =

You can clock chirp a lot of machines.

I think the problem is that Apple's engineers envisioned a product similar to
the 475, but with a faster clock. They built the roms to deal with this
product at the same time as the 475. Thus the 475's roms check the clock
speed to see what model they are.

The fact that no ID 90 machine's come out is a good sign that the product
didn't happen. I checked Code Warior 10 (not the latest, but..) and 90's
not defined.

> When I first started to work with this issue, I was considering if I
> shuld make the changes to the kernel source or the Booter source. But
> when it comes to compilation time, the choise was clear as water "The
> Booter source".

I'd say both. Just teach it that 90 is the same as 89. Don't change
the value, just add to the case statements.

> > > My next wish is to get the internal video to work. Maybe I can hard c=
> ode
> > > this part to ;-)
> 
> Do you hav an answer to this question? Is there some good way to check
> for the addresses for the internal video?

MACH_MACLC475 is defined in sys/arch/mac68k/include/cpu.h on line 183. Try
adding #define MACH_MACLC475_CHIRPED 90  on the next line.

Then the only other place MACH_MACLC475 is used is in the rom setup, on line
1969 of sys/arch/mac68k/mac68k/machdep.c:
{MACH_MACLC475, "LC", " 475 ", MACH_CLASSQ,  &romvecs[9]},

Add something like:
{MACH_MACLC475_CHIRPED, "LC", " 475 ", MACH_CLASSQ,  &romvecs[9]},

Scott, Allen, Bob, how does this look?

Also, you might check the rom vectors on your machine, just to make sure
they are the same as for the non-chirped sytem.

The above two changes, assuming no ROM-vector changes, are all you need to
do to add support. Assuming your computer behaves just like a 475 w/ a
different ID.

Take care,

Bill