[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Kernel uses only half of Mac IIci memory with built-in video

On Tue, 23 Mar 2021, Brad Boyer wrote:

> On Tue, Mar 23, 2021 at 06:50:05PM +1100, Finn Thain wrote:
> > Anyway, surely this test for CPU_68020 in Source/mmu_support.c in 
> > Penguin is bogus. This must have to do with some quirk of the Mac II 
> > logic board and not the type of MMU or CPU.
> > 
> > So, why sort chunks by address on Mac II? Beats me. I guess I'll have 
> > to dig out my Mac II and try EMILE, which doesn't have that hack.
> Apparently there was a bug in the original Mac II ROM that couldn't 
> handle more than 4MB in bank A. That would mean that anyone who had more 
> than 8MB had the larger modules in bank B.

Right. And, of course, the original Mac II is not the only model where 
bank B might be larger than bank A.

Also, I found that it's not just the IIsi that has a small bank A that's 
all soldered-in. The IIvi/vx and Quadra 700 are in the same category.

It appears that both Penguin and EMILE are likely to disappoint on these 

It's a pity bootloaders don't share more code. I think there's a good 
argument for fixing this in EMILE and then wrapping a MacOS GUI around it, 
that could supercede Penguin eventually.

Reply to: