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From: gillies@uiucdcsp.UUCP
Newsgroups: comp.sys.mac
Subject: Re: support for older machines
Message-ID: <76000056@uiucdcsp>
Date: Sun, 29-Nov-87 19:46:00 EST
Article-I.D.: uiucdcsp.76000056
Posted: Sun Nov 29 19:46:00 1987
Date-Received: Wed, 2-Dec-87 04:07:38 EST
References: <4161@utai.UUCP>
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Nf-ID: #R:utai.UUCP:4161:uiucdcsp:76000056:000:1328
Nf-From: uiucdcsp.cs.uiuc.edu!gillies    Nov 29 18:46:00 1987


From a technical standpoint, I cannot see how Apple could AVOID
withdrawing support for some of the older machines.  It is nearly
impossible to support so many machines in so many configurations.

Assumine you plan ahead, I would estimate that if a new release takes
N units of work, then a new release for two versions of the underlying
O/S + Hardware probably takes N^2 work.  If there are three versions
of the O/S, it's N^3 work.  If Apple were to support all previous
versions, you would never see anything new from Apple.

One of the problems is testing.  If you support 10 major pieces of
application software (and Apple maintains more), then you must test 10
packages when you release a new system/finder.  If you support 2
system/finders, you must test 20 times.  3 system/finders, 30
tests.  And bug track very extremely complex.

Another problem is version control and forked development.  If each
piece of software must be slightly different for each system/finder,
then you have programmers knifing themselves because they cannot keep
track of what goes with what and which bug was in which release of
system x.y.z.  Not to mention the hassles in trying to write
conversion code (say, from MacWrite 9.8 to MacWrite 10.0 files).

Don Gillies {ihnp4!uiucdcs!gillies} U of Illinois
            {gillies@p.cs.uiuc.edu}