WG&L incotax (1985) calculator by Texas Instruments

Date of introduction:  1985 Display technology:  LED-stick
New price:   Display size:  10 (8 + 2)
Size:  6.4" x 3.2" x 1.5"
 162 x 81 x 37 mm3
Weight:  8.5 ounces, 240 grams Serial No:  4923316
Batteries:  BP1A Date of manufacture:  wk 38 year 1980
AC-Adapter:  AC9131 Origin of manufacture:  USA
Precision:  13 Integrated circuits:  TMC0501E, TMC0580 (CD2400), TMC0580 (CD2401), TMC0573, TMC0591, Toshiba TC5047AP
Logic:  AOS - 8 Pending Operations, 9 ()    
Memories:  0-60    
Program steps:  480-0 Courtesy of:  Joćo Oliveira

The innovative TI-58 was the perfect base for a lot of customized calculators. The idea behind these products was the novelty of the Solid State Software Modules™ with up to 5000 program steps.

TI-58-INCOTAX_3.jpg (21424 Byte)The incotax application was developed by the Bureau of National Affairs, Inc., Washington D.C. in 1985 to calculate Federal Income Taxes and distributed by Warren, Gorham & Lamont, Valhalla NY (WG&L). We know this kind of modules already from the CAL-Q-TAX application.

TI-58-INCOTAX_2.jpg (40491 Byte)Compared to the usual drop-in modules these calculators use an extender developed by Hand Held Products. The extender connects to the small contacts below the lid of the calculator backside. 

The similar tax planner introduced by WG&L in 1982 and the original incotax calculator make use of a traditional Solid State Software Module.

TI-58-INCOTAX_1.jpg (35609 Byte)One advantage of the expander is the convenient module exchange during operation with a PC-100C printer cradle.

TI-58-INCOTAX_4.jpg (48488 Byte)Inside the module we notice a standard EPROM HN27128 manufactured by Hitachi. The capacity of this UV-erasable memory is 16k program steps compared to the 5k of the original software modules. The logo "HHP" found on the printed circuit board (PCB) of the module is the abbreviation used by Hand Held Products.

TI-58-INCOTAX_PCB.jpg (145705 Byte)Dismantling the incotax calculator reveals a standard TI-58C calculator manufactured in Fall 1980. It is one of the earlier models, the printed circuit board (PCB) of the calculator was manufactured in Canada.

Compare it with a similar product by the insurance companies Agrippina, Allianz, Lloyd, LVM, Nordstern and Victoria or the Bossard screwing joint calculator. Even the French carmaker Chrysler-Simca used the TI-58, don't miss the Chrysler Credicavia. Don't miss the USMC HARRIER flight computer based on the TI-58 calculator, too.

A colorful calculator appeared with the Pool Water Analysis module.


Warren, Gorham & Lamont, Valhalla NY was founded in the 1950s, but traces its roots back to 1882, when Willard Warren started a weekly, the Connecticut Real Estate Record and Building News (later and still today, The Commercial Record). The Thomson Corporation acquired Warren, Gorham & Lamont (WG&L) in 1980. For more than three decades, WG&L was a major information source for finance professionals in companies of all sizes and industries. The WG&L product line includes some of the most valued newsletters, journals and treatises in the legal, tax and accounting fields. WG&L remains one of the most respected brands in the industry. In 1996, the tax publishing activities of Warren, Gorham & Lamont were merged with RIA.

WG&L ® is a trademark of Warren, Gorham & Lamont, Valhalla NY.

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© Joerg Woerner, November 20, 2003. No reprints without written permission.