| But what if "key1" and "key2" were defined as "static const final" and, after
compilation, burned in a PROM? That makes it exactly equivalent to the
physical, mechanical key, which as already established, is merely an instance
of a class of devices.
I own a great variety of computers, running on
everything from a 1MHz 6502
to a 4GHz Core i7, by way of PowerPCs, ARMs and
even a small MIPS box. On
many of them, I can supply the same source code to
an appropriate compiler,
and it will spit out some form of machine code that
will run on that computer.
That machine code will of course be entirely
different for a PowerPC, an ARM,
or a standard PC, but it represents the same
intended functionality.
So despite their huge variety of form and
implementation, from a few
thousand transistors in the CPU up to over a billion
transistors, they are all
instances of a class called "general purpose
computer". The software actually
running on them is entirely different, and
yet the idea behind it is the same.
For example, I can run Abiword, Gnumeric
and Inkscape on fully three-
quarters of my collection, across four distinct
Instruction Set Architectures.
And if I load one of those three software
packages on a computer, it does not
make the computer unable to run any of the
other things it did before, nor
prevent me from loading the other two - or
indeed from running them
simultaneously. Modern general-purpose computers -
where "modern"
means "designed any time in the past 20 years or so" - are
expressly
designed to permit this.
Therefore, while loading software adds
capabilities to a computer in practice,
it always had the potential
capability of performing those functions,
and it is *not* suddenly transformed
into a "special purpose computer" as a
result. If it were so transformed, it
would not be able to run Inkscape at the
same time as Abiword, or to play a CD
in the optical drive while I work. Yet I
have a counterexample right here - my
old IBM Thinkpad can do all three
things simultaneously - even while running
Windows - so any new computer
that could not would be laughed out of the
market.
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