Mariner Electronic Calculator NRC 7200

Date of introduction:  December 1971 Display technology:  LED-modules
New price:  $179.95 Display size:  8
Size:  5.3" x 3.0" x 1.5"
 136 x 77 x 38 mm3
Weight:  11.5 ounces, 325 grams Serial No:  13880
Batteries:  6*AA Date of manufacture:  mth 01 year 1972
AC-Adapter:  Custom Origin of manufacture:  USA
Precision:  8 Integrated circuits:  TMS0103
Program steps:   Courtesy of:  Joerg Woerner

You are familiar with this calculator? At first glance it looks like similar to the Bowmar 901B introduced three month earlier. The main difference is the sliding switch above the Klixon™ keypad to adjust the display format between the floating decimal system and fixed decimal for 2, 4, or 6 places. 

It is very difficult to gather additional information about this rare calculator, let us dig around.

NRC7200_1.jpg (43463 Byte)The Mariner was advertised by NSI Merchandising Inc., Des Plaines, IL in conjunction with Union Oil Company of California - better known as Unocal 76. The offer was exclusive to Union Oil Company's credit card customers. The Mariner was delivered complete with travel case, carry case and strap, AC Adaptor / Charger Unit and instructions. 

NRC7200_p.jpg (7602 Byte)The Union Oil credit card allowed two methods of payment:

$15.15 added to the Union 76 Revolving Credit 
    Account each month for 12 month
One payment of $179.95 added to the Union 76 
    Revolving Credit Account

Compared with the Bowmar's selling price of $240 the Mariner was a bargain. Don't forget, that end of the year 1971 competition was low. Most calculators used much larger housings, compare the sleek Mariner with the Sharp EL-8.

The main question is still open, who manufactured the calculator?

The sales brochure gives an important hint - we know Monsanto
introducing the first commercial LED display and Texas Instruments inventing the "calculator-on-a-chip" and manufacturing the Klixon™ keypad.

It was not unusual that Texas Instruments manufactured calculators for other companies, think about the
Radio Shack EC-200, Montgomery Ward P800 or Longines Symphonette EC. This one, too?

NRC7200_r.jpg (37432 Byte)Usually the backside  of a calculator gives more information, calculators manufactured by Texas Instruments use often abbreviations like TXI or provide a service address in Dallas. This Mariner doesn't. The only identification label is once again "NRC MADE IN USA NEW YORK". We know a company NCR (National Cash Register) selling calculators in the US manufactured by Busicom, Japan but we never  heard something from NRC

Let us read the the fineprinted of the advertising once again:
Mariner ELectronic CalculatoOR - MELCOR. Every serious collector of early electronic calculators knows "The Complete Collector's Guide to Pocket Calculators" written by Guy Ball & Bruce Flamm. It states:

"Melcor Electronics Corporation of Farmingdale, New York (USA) was one of the first US companies to enter the pocket calculator business. Like Bowmar, they were known for quality products but only made calculators for a few years." 

This Mariner NRC 7200 seems to be the first Melcor calculator! The association with Texas Instruments seems to be limited on delivering the keyboard and calculator IC. Maybe that engineers of Texas Instruments developed the electronic circuit of the calculator, it is very similar to the later Datamath Version 1 (and the Bowmar 901B). Later products sold under the Melcor label used completely different technology, don't miss the Melcor Model 380 and Model 1000.

In the meantime fellow collector Frank Boehm proofed Melcor as manufacturer of the Mariner NRC 7200. He located a small stamp with the following text:

(516) 694-5570

Don't miss the TI-1706 III sold more than 25 years later to UNOCAL 76 customers.

Klixon™ is a trademark of Texas Instruments.

Unocal 76

The Unocal Corporation NYSE: UCL, based in El Segundo, California, was founded in 1890 as the Union Oil Company of California. Unocal is also known as Unocal 76. 
Union 76 gasoline is no longer sold by the company, which sold its retail operations to ConocoPhillips Co. In April 2005, the company agreed to a merger with ChevronTexaco; however, in June 2005, the Chinese oil company CNOOC (China National Offshore Oil Corporation) made a rival $18.5 billion bid. Ultimately, on July 19, 2005, Unocal agreed to merge with Chevron.


Unocal was founded on October 17, 1890, when it was incorporated in Santa Paula, California, as the Union Oil Company of California. The company was formed by the merger of co-founders Lyman Stewart, Thomas Bard, and Wallace Hardison's holdings. Union Oil moved its headquarters to Los Angeles in 1901. The original headquarters in Santa Paula is a California Historical Landmark. The company expanded to national status in 1965, when Union Oil merged with the Pure Oil Company of Illinois. Over the next two decades, Union became the major oil producer in southern Alaska and a major natural gas producer in the Gulf of Mexico. The company was reorganized in 1983 and the Union Oil Company of California became an operating subsidiary of a new holding company, Unocal Corporation.

Union 76™ is a trademark of ConocoPhillips Co.

From Wikipedia, the free encyclopedia.

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© Joerg Woerner, February  23, 2002. No reprints without written permission.