[rescue] newest rescue

[Nathan Raymond]

On Wed, Feb 3, 2016 at 3:09 PM, Toby Thain <toby at telegraphics.com.au> wrote:

> On 2016-02-03 1:07 PM, Richard wrote:
>
>> In article <CAPFCoitX2OtQ0XpVi7WwzwS0KaRbh5VGYhbUChgOvGMWr+=
>> EpQ at mail.gmail.com>,
>>      John Hudak <jjhudak at gmail.com> writes:
>>
>> As an addendum to my own post, in comparison to Sun, Apple had used the
>>> 680xx cpus but, in comparison, they were making 'toys'... [...]
>>>
>>
>> It also had cooperative multi-tasking.  MacOS didn't get true
>> pre-emptive multi-tasking until OS X, IIRC.
>>
>>
> Or memory protection.


Correct, though Apple did introduce a weak form of protection by
introducing guard pages - if an application crashed and the application's
heap was corrupt, it could be thrown away and the OS would keep running.
They also did what they could to support multi-threading and SMP, but
maintaining backward compatibility meant those features could only be used
by special processes without a UI, but that allowed applications like Adobe
Photoshop and 3D renders to take advantage of hardware accelerators and
multiple processors.

Of the same era (and also 68k), the Amiga lacked memory protection. It did
have pre-emptive multitasking however (though some like Linus Torvalds have
argued that the lack of memory protection disqualifies it from being a true
pre-emptive system). Despite many efforts over the years, nobody has
brought memory protection to AmigaOS, presumably because the message
passing and inter-process communication is built on the assumption that
there is no memory protection.

- Nate