New to threads. How do they work?

[Edmond Dantes]

Dennis Lee Bieber wrote:

> On Sat, 22 Jul 2006 17:19:22 +1200, Lawrence D'Oliveiro
> <ldo at geek-central.gen.new_zealand> declaimed the following in
> comp.lang.python:
> 
>> 
>> Perhaps because with threads, data is shared by default. Whereas with
>> processes, it is private by default, and needs to be explicitly shared if
>> you want that.
> 
> Or just that the "name" "thread" was a late-comer for some of us...
> 
> The Amiga had "tasks" at the lowest level (these were what the core
> OS library managed -- that core handled task switching, memory
> allocation, and IPC [event flags, message ports]). "Processes" were
> scheduled by the executive, but had additional data -- like stdin/stdout
> and environment variables... all the stuff one could access from a
> command line. Or, confusing for many... Processes were "DOS" level,
> Tasks were "OS" level.

On the Amiga, everything was essentially a "thread". There was *no* memory
protection whatsoever, which made for a wickedly fast -- and unstable --
OS.

Now, before Commordore went the way of the Dodo Bird, there was some
discussion about adding memory protection to the OS, but that was a very
difficult proposition since most if not all of the OS control structures
were just that -- basically c "structs", with live memory pointers handed
around from application to kernel and back.

I think we could've done it eventually, but that ship sank. All because of
the idiots there that was upper management. But I digress.
 
-- 
-- Edmond Dantes, CMC
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