Both Owen and I were in Rochester in the mid 70’s. Owen was a Xerox and I was 
at the U of Rochester. We were working with the same people but somehow never 
met.

In the early 80’s I did some consulting with National Computing Systems. They 
made the machines that read and scored standardized tests, the ones in which 
you answered by darkening little circles with a pen or pencil. The machines 
were very much like copiers and had many of the same problems with papers. The 
way they worked was that as the paper was passed through the system it went 
through a pairs of leds and photo detectors that would sense if a circle was 
filled.  You remember that on these kinds of test all the circles had to be 
lined up vertically so as to match the positions of the sensors on the scoring 
machine.  

The nature of paper, as described in the New Yorker article posed some 
interesting problems. First, paper is noisy. When you shine light though , you 
can see this, so the scoring can get messed up with cheap paper. But the big 
problems were due the thermal properties of paper and lawyers.  Paper expands 
and contracts with temperature. Under high temperature, the paper can expand so 
much that the circles may not be line up with the sensors and the test will be 
scored incorrectly. At that time, California gave all its standard tests using 
these machines. The state was faced with a number of lawsuits from parents 
contending that their kids’ test were misscored, which occasionally was true 
due due to thermal expansion of the test paper. The state would up deciding to 
warehouse all tests so they would be available for inspection. It was costing 
them quite a bit so NCS was designing a better machine, which was what I was 
consulting about. The solution had much in common with copiers and used a 
one-dimensional scanner the width of page that could read across the paper as 
it flowed by. With that, the computer could detect filled/unfilled circles even 
if the page expanded or contracted.

Ed

_______________________

Ed Angel

Founding Director, Art, Research, Technology and Science Laboratory (ARTS Lab)
Professor Emeritus of Computer Science, University of New Mexico

1017 Sierra Pinon
Santa Fe, NM 87501
505-984-0136 (home)                     an...@cs.unm.edu 
<mailto:an...@cs.unm.edu>
505-453-4944 (cell)                             http://www.cs.unm.edu/~angel 
<http://www.cs.unm.edu/~angel>

> On Feb 11, 2018, at 9:10 PM, Tom Johnson <t...@jtjohnson.com> wrote:
> 
> Why some of us like applied complexity.
> 
> https://www.newyorker.com/magazine/2018/02/12/why-paper-jams-persist 
> <https://www.newyorker.com/magazine/2018/02/12/why-paper-jams-persist>============================================================
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