This isn't just "a Heathkit". This is a Heatkit analog computer, one of a number of analog computer models produced by Heath. And it is a nicely done article, describing a restoration and now-unfamiliar components; vacuum tubes not the least of them. The subject functionality itself is unfamiliar. Now 21st century persons have been introduced to this 1960's tech and mid-century analog computers. There's a companion brief article on earlier large scale analog computers and their role in engineering and science. So persons interested in these subjects should review this article. Regards, Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net