On Wed, 15 Apr 1998 [log in to unmask] wrote:

> One of our systems engineers was joking around the other day and said:
> "The difference between hardware and software is that the more you play
> with hardware, the more likely you are to break it, but the more you play
> with software the more likely you are to FIX it."

  I often tell my students that the difference between hardware and
  software is that hardware, the physical world, is pre-constrained
  by the laws of phyics.  In the software world, one is only constrained
  by one's imagination.  In the physical world, I am dealing with a
  three-dimensional world in which gravity, inertia, and entropy have
  dominance.  In software, I can create a twenty-seven dimensional
  world in which I suspend gravity, eliminate inertia, and have no
  need to worry about entropy.  Of course, the physical world may
  intrude itself upon my program because I need a physical platform
  on which to execute my code, but my program itself is not so constrained.

  In Ada, we define a constrained universe in an attempt to map our program
  design to the physical boundaries of the environment we intend to
  model.  I have a longer article in progress that explores this in
  more depth, but decided to share it with this list since it was
  mentioned.

  Richard Riehle
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