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From: lsr@apple.UUCP (Larry Rosenstein)
Newsgroups: comp.sys.mac
Subject: Re: Multi-tasking Finder (finally)
Message-ID: <1478@apple.UUCP>
Date: Fri, 14-Aug-87 19:07:58 EDT
Article-I.D.: apple.1478
Posted: Fri Aug 14 19:07:58 1987
Date-Received: Sun, 16-Aug-87 07:11:23 EDT
References: <1659@leadsv.UUCP>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Organization: Advanced Technology Group, Apple Computer
Lines: 90
Keywords: MacWorld Finder announcement

In article <1659@leadsv.UUCP> morse@leadsv.UUCP (Terry Morse) writes:
>
>o	is it _really_ multitasking or more like Switcher?

It works much like Switcher.  Whether or not you consider that multitasking
is up to you.  

Some improvements over Switcher:

If you try to Restart (in the Finder) and have application open, Multifinder
will try to Quit from them automatically.  (It tries to locate a Quit
command, and "coerces" the application into running it.)

Application that are written with Multifinder in mind can make certain calls
to it.  For example, the new Finder will run in a very small amt of memory
(~160K), but when you do a disk copy, it asks Multifinder to allocate some
unused memory.

Another Multifinder call you can make is WaitNextEvent.  It is like
GetNextEvent except that the application will be suspended until an event is
actually available.  There are other parameters to allow the application to
get a null event after a certain time, and if the mouse leaves a certain
area. 

You configure Multifinder from the Finder.  Under Set Startup you have the
option of using Multifinder or not.  You can also have Multifinder startup
and automatically open any combinations of documents (not just
applications) and DAs

Under Get Info, you can set the amt of memory assigned to an application.

The System Heap under Multifinder is dynamically resizable.  All resources
that come from the System file are loaded into the System Heap.  This
includes fonts and DAs.  This means, for example, that DAs don't go away
when you launch an application.

Programs that implement sublaunching according to the recent Tech Note (eg,
MPW 2.0) will work under Multifinder and will result in launching a new
process.  For example, if you are using MPW, you can run an application and
still have MPW available in a separate process.

>o	which programs cannot be run concurrently?

Most applications that were compatible with Switcher will be compatible with
Multifinder.  (According to one of the Multifinder people, there are
applications that did not work with Switcher but DO work with Multifinder,
and vice versa.)

>o	how do we get a copy, and when will it be available?

It will be available in a month or so.  There will be a $49 package you can
buy which will give you 4 diskettes and documentation.  The 4 diskettes will
have installer scripts for the new System Software and printers, and will
have the latest versions of Font/DA Mover, etc.  

>o	what's the minimum hardware configuration?

You need 1Mb and 128K ROMs or later.  More memory will allow you to run
more application simultaneously.  With Multifinder 1.0b6 (the latest so
far), you have about 570K left over when running on a Mac Plus with 1Mb.
The actual amount will depend on the number of fonts/DAs/etc. you have.
(This number was derived by booting the Multifinder disk itself, which has a
minimal set of fonts & DAs.)

It is definitely worthwhile to use Multifinder on a 1Mb machine, because it
makes going back to the Finder very fast.  Also, there is no need for the
DAs that manipulate files, because the Finder is always around.

People argue that Multifinder is not "real" multitasking because it uses
non-preemptive scheduling.  I consider that a matter of semantics and don't
want to argue the point.  I do want to make 1 point: 

Despite its name, Multifinder is really an extension to the operating
system, and it was designed and implemented by people with O/S backgrounds.
One of their goals was to design a very solid O/S, rather than hack together
something that worked.  

Multifinder is described in the press release as the first-generation
multitasking Mac O/S.  This implies that there will be future releases that
include features such as pre-emptive scheduling, IPC, etc.  

-- 
Larry Rosenstein

Object Specialist
Apple Computer

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