GTCO was established in 1975 in Rockville, Maryland by two graduates of the Stevens Institute of Technology in Hoboken New Jersey . In 1985, GTCO moved to its current location in Columbia, Maryland. GTCO Corporation patented the first electromagnetic digitizer. In 1995 GTCO acquired the assets of Science Accessories Corporation. In 1998, GTCO acquired the assets of Kontron Gmbh. In 1999, GTCO acquired the assets of CalComp Input Technologies, which itself had previously acquired Talos and Summagraphics Corporation, which had acquired Houston Instruments. With the acquisition of CalComp Input Technologies, GTCO began doing business as GTCO CalComp Inc.
AgC Technology, a division of GTCO CalComp, has over 30 years of experience with conductive ink printing. Though the company specializes in conductive ink printing, graphic ink printing services are provided when part of an integrated project.
In addition to digitizers and graphics tablets, GTCO produces interactive whiteboards, pads and audience response systems under the InterWrite brand name. In 2004, GTCO acquired Educue, LLC and began offering the PRS (Personal Response System), used for education and training throughout the world.
In December 2008, GTCO Corporation doing business as Interwrite Learning and GTCO CalComp was acquired by eInstruction Corporation, Denton, TX. eInstruction is the world leader in audience assessment systems with the Classroom Performance System (CPS)and the Interwrite PRS system.