23 Sep
2014
23 Sep
'14
8:15 a.m.
On Mon, Sep 22, 2014 at 01:34:42PM +0300, Andriy Romanenko wrote:
So, basically multitasking/timesharing on the machine
without MMU would
require some kind of soft-interpreter (forth, basic, etc.) to prevent
processes from direct access to memory locations (hence prevent system
crashes).
Or else just don't claim it's crash-proof in the first place. RT-11FB
works beautifully with cooperative multithreading, and preemptive
multithreading can work just as nicely with no protection. Having the OS
survive application crashes may seem like a noble goal, but in real life
(especially doing some kind of control), how useful is a computer that's
stopped doing the one thing you asked it to do? You may well end up
rebooting anyway just to get a clean restart of all the application's bits
and pieces.
FORTH is *traditionally* threaded (and I think multithreading was usually
done by executing some fixed number of words and then switching threads),
but it need not be (mine isn't, and uses the KW11L clock to preempt).
And as Paul said, either way, FORTH gives you enough power to kill yourself.
John Wilson
D Bit