Texas Instruments 40 distributed by Koh-I-Noor Hardtmuth

Date of introduction:  1977 Display technology:  LED-stick
New price:   Display size:  8 (5 + 2)
Size:  5.8" x 3.1" x 1.4"
 148 x 78 x 36 mm3
Weight:  4.0 ounces, 114 grams Serial No:  179551
Batteries:  9V or RK2 Date of manufacture:  wk 21 year 1977
AC-Adapter:  AC9900/R Origin of manufacture:  Italy (RCI)
Precision:  10 Integrated circuits:  TMS0981
Logic:  AOS - 4 Pending Operations, 15 ()    
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

Texas Instruments 40? We were really surprised to locate in December 2012 this unusual looking calculator on the Italian eBay site. It is obvious that the model 40 - manufactured for Koh-I-Noor Hardtmuth - is a hybrid of three different products:

The basic functionality is borrowed without any doubts from the TI-30 introduced in 1976
The double-shot injection molded keys are known from the Business Analyst-I
The yellow-brown keyboard plate is... unique

Dismantling this model 40 manufactured in 1977 reveals a standard TI-30 printed circuit board (PCB) with the well-known TMS0981 single-chip calculator circuit.

This unique model 40 was replaced in 1978 with the model professional. Don't miss the model Studio 29 and model 45.

Interested in rare calculators with the "40" designation? Don't miss this SR-40

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If you have additions to the above article please email:

Joerg Woerner, April 6, 2011. No reprints without written permission.