Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!njin!princeton!udel!mmdf
From: iphwk%MTSUNIX1.BITNET@cunyvm.cuny.edu (Bill Kinnersley)
Newsgroups: comp.sys.amiga
Subject: Re: Need info on exceptions
Message-ID: <3794@louie.udel.EDU>
Date: 23 Aug 88 13:31:54 GMT
Sender: mmdf@udel.EDU
Lines: 44

[In "Re: Need info on exceptions", Ronald G Minnich said:]
>
> In article <413@brambo.UUCP> morgan@brambo.UUCP (Morgan W. Jones) writes:
> >One approach that seems reasonable would be to send a message to the
> >timer.device asking it to send you a message in ten minutes (600 secs).
>    Hmm, we have a very nice OS here with a shared address space and
> named blocks of memory and lightweight tasks and ....
>    we are still thinking in terms of Unix.
>
> Or, maybe:
> Spawn a lightweight process (task is such a better word,
> but Mach kinda changed the meaning). Since it shares your
> context it *knows* where to look and how often to print.
> I am lying maybe since i have not done much with tasks.
> Can someone flesh this one out?
>
>    On unix you HAVE to have the signal cause sharing data in
> memory is so damn hard. On amiga sharing (even unintentional) is
> the easiest thing. Many processes can easily share an array. So
> why not do it, and save yourself the trouble of having signal
> handlers and such?
>
In principle, Tasks are not supposed to know about each other's memory
space.  In practice, the Manx geta4() function makes the globals
common.

I would think the "correct" way on the Amiga would be to send a
message to the Task with the address of the array to be accessed,
then wait for a reply.

Even if Tasks are directly sharing memory, they need to be synchronized
to avoid reading and writing data at the same time, so you do need
at least a signal.


--

Bill Kinnersley
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