Kinpo Electronics, Inc., an ODM company, designs and manufactures products for other companies. This author is aware of Kinpo designed calculators being sold under the Citizen, Datexx, and Hewlett-Packard brands. Kinpo has also manufactured calculators under contract for Texas Instruments.
Below are links to self-test instructions for Kinpo manufactured calculators.
DS-834 Scientific Calculator - also known as: Kinpo SR19S1, Citizen SRP-285IILast updated December 3, 2004