*** Ideas needed for developing interactive displays....

From: Stan Sieler <sieler_at_allegro.com>
Date: Thu Sep 9 21:17:45 2004


> Most of our displays here at the museum are pretty static.....
> we are looking for ideas on introducing some interactive component... ideas
> folks?

I just got back from Boston (www.noreascon.org), where I happened
to visit the Museum of Science. On the second floor, they've got
a history of computers display with a couple of interesting
interactive displays.

1. core memory

They had a large size plane of core memory (about 1 foot by 1 foot)
holding a total of 6 (yes: SIX!) bits of memory. The display allowed
the visitor to press one of two buttons to select a row, and one of
three buttons to select a column. By pressing one of each (at the
same time) you stored a bit into that core (can't recall if you could
choose between 1 and 0). (And, there was an "erase" button, which may
have erased all 6 bits.) To see how the core was set, there were 6
small compasses...one by each core. The cores were *large*, about
1.5 to 2 inches in diameter. If you changed the setting of a bit, you
saw that bit's compass needle swing aroung 180 degrees (real compasses, BTW).
In short, a great visual aid to understanding how core memory works.

2. disk drives

They had a model of a disk drive, with one spinning platter (18" in
diameter?) and a head mechanism (the mechanism didn't move, sigh).
The platter had two tracks of data, with about 8 bits per track,
giving the "drive" a grand total of 2 BYTES of storage.

The visitor could press one
button to select a track, and could then press "1" or "0" (IIRC) to
record that value onto the bit ... as it passed under the disk head.
How could you tell when the bit was passing under the head? Each bit
was a magnetized donut, with one half painted red, mounted in a hole
in the platter (about a 2" hole) suspended on an "axle" that was
parallel to the platter (and capable of rotating).
I assume there was some kind of small magnet, or adequate friction,
to prevent the donut from rotating at random. The disk head was an
electromagnet, which would cause the
red half of the donut to either be attracted (leaving the red half
"face up" (let's call that a 1) or repelled (leaving the red half
"face down" (a 0).

The head mech contained a sensor to read the value of the bits as
they passed under the head, and there were a pair of LED displays to
show the status of the 8 bits (so the disk was probably hard sectored :)
(yeah, such a displau isn't realistic, but it was nice to have.)

Both displays were fun to use!
Stan Sieler
Received on Thu Sep 09 2004 - 21:17:45 BST

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