[vcf-midatlantic] vacuum tube computers, was Re: Museum Report 2017-11-26 November 26, 2017

william degnan billdegnan at gmail.com
Sun Nov 26 22:57:08 EST 2017


Get an old smart phone and open it up to expose the circuit board, show to
the visitor and ask the person to note how small the individual components
are, like a little city.  Many differnt types of components
  Then, say before computer board components got small enough to make
things like smart phones possible they used tubes and other larger
components to do the same sort of things.  Tubes used a lot more power and
generated a lot more heat than today's equivalents.

If a smart phone was full of tubes and associated 50's era components
instead of today's smaller components the phone would have to be the size
of Camp Evans.

The MIT machine we have in the museum display is not anything like a cell
phone however it's an analog computer sort of.  Its more actually a bunch
of Philco analog rack units that would have been part of a larger system
plus a plotter and instruments generating "input".  I have materials at my
house that explain some of the rack components I promise next time I come
up I'll try to put something together to explain what the MIT computer
likely would have done.  Also, as they are now the rack components are in a
disorganized impractical configuration. We need to put them together into a
more likely configuration asap.  That would be a good thing to do next
workshop.  The process of researching the components will help expose it's
function and help docents explain it.

As Dave said, an analog computer used tubes for different reasons than a
digital computer with logic  tubes.  There were many different kinds of
tubes then, as today there are different kinds of transistors.

Bill Degnan
twitter: billdeg
On Nov 26, 2017 9:22 PM, "Evan Koblentz via vcf-midatlantic" <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> 8 yrs is probably too young for us to explain any such details. With a
> child that young, I just tell them computers used to be this large when
> their grandparents or greatgrandparents were their age, and leave it at
> that. For teens or precocious adolescents (or clueless adults!), I explain
> that a vacuum tube is simply a predessor to transistors but that it does
> the same basic thing: it gets electrified to represent a digital 1 or
> turned off for a digital 0. If they want to know how a tube or transistor *
> actually works * then I suggest they visit the radio museum. :)
> On Nov 26, 2017 9:13 PM, "Jeffrey Brace via vcf-midatlantic" <
> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> > How would you explain the George Philbrick machine to an 8 year old? How
> do
> > you explain what a vacuum tube actually does to an 8 year old?
> >
> > On Sun, Nov 26, 2017 at 8:50 PM, Dave McGuire via vcf-midatlantic <
> > vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
> >
> > > On 11/26/2017 04:54 PM, Jeffrey Brace via vcf-midatlantic wrote:
> > > > The parents love the explanation of the progression of technology. I
> > need
> > > > to learn more about how vacuum tube computers work to give them a
> > > > comparison.
> > >
> > >   It's important to realize that there's really no difference.  Vacuum
> > > tubes are analogous to FETs (field-effect transistors) and are simply
> > > the active switching element of tube-based digital computers, where
> > > transistors are the active switching element of solid-state computers.
> > > The logic...the instruction set, buses, etc...can be identical.  The
> > > only real reason they're not is because computer architecture has grown
> > > up alongside, but largely independent of, electronics technology.
> > >
> > >   Now if you're talking about tube-based analog computers, that's a
> > > different animal...and the same point applies there.  Analog computers
> > > are (mostly) composed of op-amps, and those op-amps can be built with
> > > tubes or transistors. (with or without multiple transistors being
> > > "integrated" into one "circuit", i.e. using integrated circuits)
> Again,
> > > the architecture is (or at least can be) the same.
> > >
> > >   The takeaway here is the importance of understanding the difference
> > > between architectures and implementations.
> > >
> > >                -Dave
> > >
> > > --
> > > Dave McGuire, AK4HZ
> > > New Kensington, PA
> > >
> >

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