Editing DECtape (section)

== On non-DEC computers ==
[[File:COI Linc Tape II drive.jpg|thumb|COI LINC Tape II drive]]
Computer Operations Inc (COI) of [[Beltsville, Maryland]] offered a DECtape [[Clone (computing)|clone]] in the 1970s.
Initially, COI offered LINC-tape drives for computers made by
[[Data General]], [[Hewlett-Packard]] and [[Varian Inc.|Varian]], with only passing reference to its similarity to DECtape.<ref>Linc Tapes, Operating System Give Users I/O Paper Tape Option, [https://books.google.com/books?id=GF_o9uVZKmgC&pg=PT14 Computerworld], Dec. 20, 1972; page 15.</ref><ref>Varian 610s Gain Direct-Access Tapes, [https://books.google.com/books?id=pWBoOXVjuZ0C&pg=PT9 Computerworld], Oct. 17, 1973; page 19.</ref>  While DECtape and LINC tape are physically interchangeable, the data format COI initially used for 16-bit minicomputers was distinct from both the format used by the [[LINC]] and the format used on DECtape.<ref>[https://archive.org/stream/bitsavers_coiCO600NP_5292542 CO 600 NP LINC Tape System for Nova Computers], Computer Operations, Inc., Beltsville, MD, Nov. 24, 1971, Doc. No. 112; Section 9.0 describes the tape format.</ref>  When COI offered the ''LINC Tape II'' with support for the [[DEC PDP-8]], [[PDP-11]], [[Data General Nova]], [[Interdata 7/32 and 8/32|Interdata 7/32]], [[HP 2100]], [[Honeywell 316]] and several other computers in 1974, the drive was priced at $1,995 and was explicitly advertised as being DECtape compatible.<ref>[http://archive.computerhistory.org/resources/access/text/2015/02/102686584-05-01-acc.pdf LINC Tape II - Direct Access Mini-Computer Mass Storage System], Computer Operations Inc., Sept. 1974; 5 pages.</ref><ref>Low Cost Tape Drives made for DEC, DG Gear, [https://books.google.com/books?id=RkAxDQnQJWkC&pg=PA33 Computerworld], June 4, 1975; page 33.</ref><ref>COI Showing Mass Storage Units, [https://books.google.com/books?id=X2ubE_4klewC&pg=PA56 Computer World], May 31, 1976; page 56.</ref>

In 1974, DEC charged COI with patent infringement. COI, in turn, filed a suit claiming that DEC's patent was invalid on several grounds, including the assertions that DEC had marketed DECtape-based equipment for over a year before filing for the patent, that they had failed to properly disclose the prior art, and that the key claims in the DEC patent were in the public domain. The [[US Patent and Trademark Office]] ruled DEC's patent invalid in 1978.<ref name=DECtapePatent /><ref>Martha Blumenthal, Fraud Ruled in 1968 DEC Tape Patent, [https://books.google.com/books?id=r_blY9oI5CYC&pg=PA65 Computerworld], May 1, 1978; page 65.</ref>  The court case continued into the 1980s.<ref>Rya W. Zobel, [http://www.ecases.us/case/mad/2125524/digital-equip-corp-v-parker Memorandum of Decision], Digital Equip. Corp. v. Parker, April 2, 1980.</ref><ref>Levin H. Campbell, [http://law.justia.com/cases/federal/appellate-courts/F2/653/701/313062/ Court ruling], Digital Equipment Corporation, Plaintiff, Appellant, v. Sidney A. Diamond, Etc., et al., 653 F.2d 701 (1st Cir. 1981), June 12, 1981.</ref>