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Re: Re: Can a machine test itself? + other issues

"BIOS" is just the acronym for the name IBM chose around 1980 for their
firmware interface when they built the PC.

The issue you seem to raise relates to the presence of an "operating
system" that is a general program providing services and control to
application programs.  In your embedded systems, the operating system is
likely to be a stripped-down program more tightly coupled, as you say,
to the applications.

The issue is one of generality versus tailoring.  Generality puts stuff
in the firmware interface and the operating system that isn't needed by
every application.  A voting system (or a pacemaker, for that matter)
isn't also going to be used to word process business letters.  And all
that extra stuff that isn't needed for what the system actually does is
a source of concerns for integrity, safety, and reliability.

The bottom line is that it is cheaper to throw in the kitchen sink, even
if you don't need it, but if you do your integrity, safety, and
reliability may go down the drain.

Stan Klein

On Tue, 2004-12-07 at 22:38, Vincent J. Lipsio wrote:
> > Every computer system needs some kind of firmware to interface the
> > operating system to the physical hardware.  The BIOS just happens to be
> > the PC name for that function.
> Stan,
> Point well taken.  However, my perception is that the use of the term "BIOS"
> suggests an assumption that the system is, in fact, a PC, and not hardware
> designed for the purpose, with consequent presence of all sorts of stuff not
> related to voting, both hardware and software, and, therefore, many more
> chances for hidden problems.  I am accustomed to designing systems with
> absolutely no unused components, hardware or software, to reduce the cost
> of validation and minimize the risk of some wayward component adversely
> affecting the system.
> Also, the bootstrap and ROM monitor (which, i believe, is what a PC's BIOS
> is) are now often linked with the application code on embedded systems.
> And, a BIOS is generally perceived as a black box that can be substituted
> with any other BIOS designed for the same generation of hardware; hence, this
> thread's original author's comment, "I have been inquiring about a foolproof
> way to verify a BIOS.  I'm not sure that one exists."
> Vince Lipsio
> Every program has at least one bug and can be shortened by at least one
> instruction -- from which, by induction, one can deduce that every
> program can be reduced to one instruction which doesn't work.
Stanley A. Klein <sklein@cpcug.org>