Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!uunet!super!rminnich
From: rminnich@super.ORG (Ronald G Minnich)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Need info on exceptions
Message-ID: <658@super.ORG>
Date: 26 Aug 88 15:06:19 GMT
References: <4989@pasteur.Berkeley.EDU> <566@wuphys.UUCP> <1754@munsell.UUCP> <413@brambo.UUCP> <632@super.ORG> <414@brambo.UUCP>
Sender: uucp@super.ORG
Reply-To: rminnich@metropolis.UUCP (Ronald G Minnich)
Organization: Supercomputing Research Center, Lanham, MD
Lines: 33

>In article <632@super.ORG> rminnich@metropolis.UUCP (Ronald G Minnich) writes:
>>How about (let's be gross now)
             ^^^^^^^^^^^^^^^^^^
	     And I Meant Gross- Get It?
You know, one gets the feeling that one's messages are not
being read well. What would Miss Manners think?
   Look, those of you that haven't, take a look at any 
available amiga device driver. What you will begin to see
is that the amiga rom kernel is built around the idea of your
basic message-passing model. But what is passed in the messages?
data structures with pointers in them! An idea central to the Amiga
is that an address in any tasks address space is not a virtual 
address but a physical memory address. That means that you can hand 
a pointer off to another task and it will be valid in THAT tasks's address
space. There is a nice term for this- which i have just forgotten,
damn it- but the Sprite machine being built at Berkeley uses this idea. 
It is nice. 
   The point is, yes on Unix to get state information out of a 
process you really need to use signal(). On the amiga, there 
are better ways to do it, that involve standard mechanisms
(e.g. PutMsg or something else), that result in a much nicer 
design. And the basic heart of the nicer design is the fact that you
can share memory easily.  You don't need to do mmap() or some other 
ugly thing. 
   And yes, of course, if you have more than one variable you start
to get into the need for semaphores. Guess what. The amiga has 
very nice Semaphore calls that work! So USE THEM. Big Deal.
   My main point is that we should not take a problem-solving
methodology that applies to Unix and drop it right onto the 
Amiga. There are in many cases ways to do things on the Amiga 
that are BETTER than their counterparts on Unix. USE THEM.
   Two-message-long-flame-off.
ron