ZMARCO is an Open Archive Initiative Protocol for Metadata Harvesting (OAI-PMH) 2.0 compliant data provider. The 'Z' in ZMARCO stands for Z39.50; 'MARC' stands for MAchine-Readable Cataloging; and the 'O' stands for OAI.
A calculator that shows how it got its answer! It supports variables (X, Y, Z etc.) and many pre-defined constants such as Pi etc. It also has most if not all the functions of a Scientific calculator.
It was coded in VB6 but was updated and is now VB.NE