Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!pt.cs.cmu.edu!a.gp.cs.cmu.edu!koopman
From: koopman@a.gp.cs.cmu.edu (Philip Koopman)
Newsgroups: comp.lang.forth
Subject: Re: Consistency "slammed," by CM himself.
Summary: lifetime software costs
Message-ID: <10613@pt.cs.cmu.edu>
Date: 30 Sep 90 17:24:30 GMT
References: <1795.UUL1.3#5129@willett.pgh.pa.us>
Organization: Carnegie-Mellon University, CS/RI
Lines: 29

In article <1795.UUL1.3#5129@willett.pgh.pa.us>, dwp@willett.pgh.pa.us (Doug Philips) writes:
> I am not (yet anyway) convinced that "programming costs are
> one-time."  Perhaps that is due to my inexperience as a Forth
> programmer.
Programming costs are almost never one-time.  The bigger and
more complex the project, the less likely that the first release
of software even grossly approximates the required functionality
(i.e. the spec., which is probably not what the customer/user
wanted either).  The traditional numbers are 20% to
create a program, 80% of costs for lifetime maintenance, where
maintenance is largely to correct/enhance the software.
Much of the problem is language-independent.  A lot has to
do with the problem of "I think I might understand what I
thought I heard you ask for, which may or may not be
what you actually thought you might want, assuming that
you really understand the problem you want to solve " in spec. writing.

Interactive development in Forth and the ability to quickly
bring up prototype systems gives more chance for the programmer
and customer to come to terms on what the *real* requirements
are (not the ones in the spec.).  BUT, this is probably only
an advantage on small systems where everyone involved can
fit around a CRT and knock heads until things are resolved.

  Phil Koopman                koopman@greyhound.ece.cmu.edu   Arpanet
  2525A Wexford Run Rd.
  Wexford, PA  15090
Senior scientist at Harris Semiconductor, and adjunct professor at CMU.
I don't speak for them, and they don't speak for me.