[rescue] Mac Appliance

[Dave McGuire]

On August 3, dave at cca.org wrote:
> >  Preemtptive multitasking has nothing to do with virtual memory.  It
> >can be implemented on anything (within reason) that has a clock
> >interrupt...which the Mac certainly does, and did in its earliest
> >implementation.
> 
> Oh, true.
> 
> I keep forgetting that insanely weird fact: the original Lisa had
> paging but not pre-emptive multitasking.

  Eeeek, I didn't know the Lisa had paging.  That's scary.

> Ok, so why did they go with cooperative? I don't believe it was 
> considered a good idea. Pre-emptive had to have been considered
> too "expensive" in *some* fashion...

  I really have no idea.  I don't think it was a particularly good
decision, and it has resulted in some problems.  There's just no
explaining some design decisions.  Take the 8086 architecture's
segmented addressing, for example. ;)   *BARF*

           -Dave

-- 
Dave McGuire
Laurel, MD