Posts: 489
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Joined: Jan 2005
Here's the only explanation I've ever seen of it. It's from the HP Digest, Volume Four, 1978, page 33:
"A new distinctive packaging system has been designed for all new Hewlett-Packard consumer products beginning with the Series E calculators just introduced.
"The major graphic element on the package is a color grid symbolizing a mathematical matrix. This will appear on all product packages, the owner's handbooks, applications pacs and accessory packaging.
"The packaging system has been designed to make it easier for you to find the Hewlett-Packard calculator center at your favorite sales location."