On Wed, 28 Feb 1996, Ken Nakata wrote:

> > 1. How do I tell if I have a PMMU installed, or not.
> 
> I think there are utilities which tell you your system configuration
> in detail, but I don't even know the names.  I'll let other people
> answer this.  However, as far as I can tell from the boot message,
> your Mac II doesn't seem to have one.
> 
> > 2. How do I get a M68851 if I don't have one installed. I have heard they 
> > are scarce...
> 
> I know there is at least one place who carries the chip for about $90.
> I found their ad in Macworld.
> 
> Alternatively, you can get the same functionality by installing a
> 68030 accelerator in your Mac II since 68030 has a built-in PMMU with
> which NetBSD/mac68k works just fine.  I'm running NetBSD/mac68k on an
> SE/30 beefed up (a bit ;-) by DayStar PowerCache (68030+68882@40MHz)
> with the secondary cache disabled (NetBSD doesn't boot with the
> secondary cache enabled), so I don't think you should have any problem
> with a 33-40MHz 68030 accelerator with no secondary cache on a Mac II.
> 
> ken
> 

Crack the case and look for a chip with the motorola logo and the 68851
number on it.  it probably looks just like the 68020 chip only
a little smaller.

---------
Christopher R. Bowman
crb@eng.umd.edu
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