From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Sun,  6 Sep 2009 17:51:33 +0100
From: Eris Discordia <eris.discordia@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Message-ID: <5F3D5E186520F1434C6EDCF9@[192.168.1.2]>
In-Reply-To: <b18ed236c4cf6d2751dfdf32fb3c8de3@quanstro.net>
References: <b18ed236c4cf6d2751dfdf32fb3c8de3@quanstro.net>
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Subject: Re: [9fans] nice quote
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> in fact, none of the things we take for granted --- e.g., binary,
> digital, stack-based, etc. --- were immediately obvious.  and it
> might be that we've got these thing that we "know" wrong yet.

I don't think we are actually in disagreement here. I have no objections to
your assertion. However, the particular case at hand indicates a different
thing than historians (of computer technology) "backporting" today's
trivial matters. I believe that a concept existed in a language
(Plankalkuel) but not the machine it was supposed to control (Z3) by all
means indicates the designer of the machine and the language was aware of
the concept but faced technical limitations of his time. Stored-program
computers weren't only consequences of a person's (von Neumann's)
genius--they also were consequences of the culmination, and return point,
of delay line technology (EDSAC's memory components).

A parallel can be drawn with the emergence of quantum mechanics. Many
students of physics who aren't taught or don't teach themselves history of
physics tend to think quantum mechanics emerged at a particular time due to
that physical thinkers shortly before the time just weren't up to the
mental challenge and it would take visionaries/revolutionaries to institute
the new understanding. Historians of physics, however, can tell you with
quite some confidence that the improvements of experimental instrumentation
and becoming technically feasible of certain experiments that weren't
feasible before around the end of 19th century were very probably a more
influential agent.


--On Saturday, September 05, 2009 20:56 -0400 erik quanstrom
<quanstro@quanstro.net> wrote:

>> > The instruction most conspicuously absent from the instruction set of
>> > the Z3 is conditional branching. [...] but there is no straightforward
>> > way to implement conditional sequences of instructions. However, we
>> > will show later than conditional branching can be simulated on this
>> > machine.
>
> i think your reasoning is going backwards in time.  the fact that
> a historian later can note that they *could* have had conditional
> branching, if they'd thought of it further bolsters my position
> that it is not immediately obvious that conditional branching
> is what you want.
>
> in fact, none of the things we take for granted --- e.g., binary,
> digital, stack-based, etc. --- were immediately obvious.  and it
> might be that we've got these thing that we "know" wrong yet.
>
> i would imagine that in 30 years there will be several "obvious"
> things about quatum computers that nobody's thought of
> yet.
>
> - erik
>